Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 26b57e2..233459c 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* kernel/lockdep.c
*
@@ -45,11 +46,14 @@
#include <linux/hash.h>
#include <linux/ftrace.h>
#include <linux/stringify.h>
+#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/gfp.h>
#include <linux/random.h>
#include <linux/jhash.h>
#include <linux/nmi.h>
+#include <linux/rcupdate.h>
+#include <linux/kprobes.h>
#include <asm/sections.h>
@@ -81,6 +85,7 @@
* code to recurse back into the lockdep code...
*/
static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
+static struct task_struct *lockdep_selftest_task_struct;
static int graph_lock(void)
{
@@ -130,26 +135,44 @@
unsigned long nr_list_entries;
static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
+static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES);
/*
* All data structures here are protected by the global debug_lock.
*
- * Mutex key structs only get allocated, once during bootup, and never
- * get freed - this significantly simplifies the debugging code.
+ * nr_lock_classes is the number of elements of lock_classes[] that is
+ * in use.
*/
+#define KEYHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
+#define KEYHASH_SIZE (1UL << KEYHASH_BITS)
+static struct hlist_head lock_keys_hash[KEYHASH_SIZE];
unsigned long nr_lock_classes;
-static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
+#ifndef CONFIG_DEBUG_LOCKDEP
+static
+#endif
+struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
+static DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS);
static inline struct lock_class *hlock_class(struct held_lock *hlock)
{
- if (!hlock->class_idx) {
+ unsigned int class_idx = hlock->class_idx;
+
+ /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfield */
+ barrier();
+
+ if (!test_bit(class_idx, lock_classes_in_use)) {
/*
* Someone passed in garbage, we give up.
*/
DEBUG_LOCKS_WARN_ON(1);
return NULL;
}
- return lock_classes + hlock->class_idx - 1;
+
+ /*
+ * At this point, if the passed hlock->class_idx is still garbage,
+ * we just have to live with it
+ */
+ return lock_classes + class_idx;
}
#ifdef CONFIG_LOCK_STAT
@@ -274,11 +297,42 @@
#endif
/*
- * We keep a global list of all lock classes. The list only grows,
- * never shrinks. The list is only accessed with the lockdep
- * spinlock lock held.
+ * We keep a global list of all lock classes. The list is only accessed with
+ * the lockdep spinlock lock held. free_lock_classes is a list with free
+ * elements. These elements are linked together by the lock_entry member in
+ * struct lock_class.
*/
LIST_HEAD(all_lock_classes);
+static LIST_HEAD(free_lock_classes);
+
+/**
+ * struct pending_free - information about data structures about to be freed
+ * @zapped: Head of a list with struct lock_class elements.
+ * @lock_chains_being_freed: Bitmap that indicates which lock_chains[] elements
+ * are about to be freed.
+ */
+struct pending_free {
+ struct list_head zapped;
+ DECLARE_BITMAP(lock_chains_being_freed, MAX_LOCKDEP_CHAINS);
+};
+
+/**
+ * struct delayed_free - data structures used for delayed freeing
+ *
+ * A data structure for delayed freeing of data structures that may be
+ * accessed by RCU readers at the time these were freed.
+ *
+ * @rcu_head: Used to schedule an RCU callback for freeing data structures.
+ * @index: Index of @pf to which freed data structures are added.
+ * @scheduled: Whether or not an RCU callback has been scheduled.
+ * @pf: Array with information about data structures about to be freed.
+ */
+static struct delayed_free {
+ struct rcu_head rcu_head;
+ int index;
+ int scheduled;
+ struct pending_free pf[2];
+} delayed_free;
/*
* The lockdep classes are in a hash-table as well, for fast lookup:
@@ -316,6 +370,13 @@
return k0 | (u64)k1 << 32;
}
+void lockdep_init_task(struct task_struct *task)
+{
+ task->lockdep_depth = 0; /* no locks held yet */
+ task->curr_chain_key = INITIAL_CHAIN_KEY;
+ task->lockdep_recursion = 0;
+}
+
void lockdep_off(void)
{
current->lockdep_recursion++;
@@ -328,6 +389,11 @@
}
EXPORT_SYMBOL(lockdep_on);
+void lockdep_set_selftest_task(struct task_struct *task)
+{
+ lockdep_selftest_task_struct = task;
+}
+
/*
* Debugging switches:
*/
@@ -371,13 +437,6 @@
return 0;
}
-/*
- * Stack-trace: tightly packed array of stack backtrace
- * addresses. Protected by the graph_lock.
- */
-unsigned long nr_stack_trace_entries;
-static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
-
static void print_lockdep_off(const char *bug_msg)
{
printk(KERN_DEBUG "%s\n", bug_msg);
@@ -387,44 +446,107 @@
#endif
}
-static int save_trace(struct stack_trace *trace)
+unsigned long nr_stack_trace_entries;
+
+#ifdef CONFIG_PROVE_LOCKING
+/**
+ * struct lock_trace - single stack backtrace
+ * @hash_entry: Entry in a stack_trace_hash[] list.
+ * @hash: jhash() of @entries.
+ * @nr_entries: Number of entries in @entries.
+ * @entries: Actual stack backtrace.
+ */
+struct lock_trace {
+ struct hlist_node hash_entry;
+ u32 hash;
+ u32 nr_entries;
+ unsigned long entries[0] __aligned(sizeof(unsigned long));
+};
+#define LOCK_TRACE_SIZE_IN_LONGS \
+ (sizeof(struct lock_trace) / sizeof(unsigned long))
+/*
+ * Stack-trace: sequence of lock_trace structures. Protected by the graph_lock.
+ */
+static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
+static struct hlist_head stack_trace_hash[STACK_TRACE_HASH_SIZE];
+
+static bool traces_identical(struct lock_trace *t1, struct lock_trace *t2)
{
- trace->nr_entries = 0;
- trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
- trace->entries = stack_trace + nr_stack_trace_entries;
+ return t1->hash == t2->hash && t1->nr_entries == t2->nr_entries &&
+ memcmp(t1->entries, t2->entries,
+ t1->nr_entries * sizeof(t1->entries[0])) == 0;
+}
- trace->skip = 3;
+static struct lock_trace *save_trace(void)
+{
+ struct lock_trace *trace, *t2;
+ struct hlist_head *hash_head;
+ u32 hash;
+ unsigned int max_entries;
- save_stack_trace(trace);
+ BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE);
+ BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES);
- /*
- * Some daft arches put -1 at the end to indicate its a full trace.
- *
- * <rant> this is buggy anyway, since it takes a whole extra entry so a
- * complete trace that maxes out the entries provided will be reported
- * as incomplete, friggin useless </rant>
- */
- if (trace->nr_entries != 0 &&
- trace->entries[trace->nr_entries-1] == ULONG_MAX)
- trace->nr_entries--;
+ trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries);
+ max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries -
+ LOCK_TRACE_SIZE_IN_LONGS;
+ trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
- trace->max_entries = trace->nr_entries;
-
- nr_stack_trace_entries += trace->nr_entries;
-
- if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
+ if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES -
+ LOCK_TRACE_SIZE_IN_LONGS - 1) {
if (!debug_locks_off_graph_unlock())
- return 0;
+ return NULL;
print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
dump_stack();
- return 0;
+ return NULL;
}
- return 1;
+ hash = jhash(trace->entries, trace->nr_entries *
+ sizeof(trace->entries[0]), 0);
+ trace->hash = hash;
+ hash_head = stack_trace_hash + (hash & (STACK_TRACE_HASH_SIZE - 1));
+ hlist_for_each_entry(t2, hash_head, hash_entry) {
+ if (traces_identical(trace, t2))
+ return t2;
+ }
+ nr_stack_trace_entries += LOCK_TRACE_SIZE_IN_LONGS + trace->nr_entries;
+ hlist_add_head(&trace->hash_entry, hash_head);
+
+ return trace;
}
+/* Return the number of stack traces in the stack_trace[] array. */
+u64 lockdep_stack_trace_count(void)
+{
+ struct lock_trace *trace;
+ u64 c = 0;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) {
+ hlist_for_each_entry(trace, &stack_trace_hash[i], hash_entry) {
+ c++;
+ }
+ }
+
+ return c;
+}
+
+/* Return the number of stack hash chains that have at least one stack trace. */
+u64 lockdep_stack_hash_count(void)
+{
+ u64 c = 0;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++)
+ if (!hlist_empty(&stack_trace_hash[i]))
+ c++;
+
+ return c;
+}
+#endif
+
unsigned int nr_hardirq_chains;
unsigned int nr_softirq_chains;
unsigned int nr_process_chains;
@@ -437,6 +559,7 @@
DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
#endif
+#ifdef CONFIG_PROVE_LOCKING
/*
* Locking printouts:
*/
@@ -454,8 +577,9 @@
#undef LOCKDEP_STATE
[LOCK_USED] = "INITIAL USE",
};
+#endif
-const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
+const char *__get_key_name(const struct lockdep_subclass_key *key, char *str)
{
return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
}
@@ -467,15 +591,26 @@
static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
{
+ /*
+ * The usage character defaults to '.' (i.e., irqs disabled and not in
+ * irq context), which is the safest usage category.
+ */
char c = '.';
- if (class->usage_mask & lock_flag(bit + 2))
+ /*
+ * The order of the following usage checks matters, which will
+ * result in the outcome character as follows:
+ *
+ * - '+': irq is enabled and not in irq context
+ * - '-': in irq context and irq is disabled
+ * - '?': in irq context and irq is enabled
+ */
+ if (class->usage_mask & lock_flag(bit + LOCK_USAGE_DIR_MASK)) {
c = '+';
- if (class->usage_mask & lock_flag(bit)) {
- c = '-';
- if (class->usage_mask & lock_flag(bit + 2))
+ if (class->usage_mask & lock_flag(bit))
c = '?';
- }
+ } else if (class->usage_mask & lock_flag(bit))
+ c = '-';
return c;
}
@@ -539,19 +674,22 @@
/*
* We can be called locklessly through debug_show_all_locks() so be
* extra careful, the hlock might have been released and cleared.
+ *
+ * If this indeed happens, lets pretend it does not hurt to continue
+ * to print the lock unless the hlock class_idx does not point to a
+ * registered class. The rationale here is: since we don't attempt
+ * to distinguish whether we are in this situation, if it just
+ * happened we can't count on class_idx to tell either.
*/
- unsigned int class_idx = hlock->class_idx;
+ struct lock_class *lock = hlock_class(hlock);
- /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
- barrier();
-
- if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
+ if (!lock) {
printk(KERN_CONT "<RELEASED>\n");
return;
}
- printk(KERN_CONT "%p", hlock->instance);
- print_lock_name(lock_classes + class_idx - 1);
+ printk(KERN_CONT "%px", hlock->instance);
+ print_lock_name(lock);
printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip);
}
@@ -596,12 +734,15 @@
* Is this the address of a static object:
*/
#ifdef __KERNEL__
-static int static_obj(void *obj)
+static int static_obj(const void *obj)
{
unsigned long start = (unsigned long) &_stext,
end = (unsigned long) &_end,
addr = (unsigned long) obj;
+ if (arch_is_kernel_initmem_freed(addr))
+ return 0;
+
/*
* static variable?
*/
@@ -626,7 +767,8 @@
/*
* To make lock name printouts unique, we calculate a unique
- * class->name_version generation counter:
+ * class->name_version generation counter. The caller must hold the graph
+ * lock.
*/
static int count_matching_names(struct lock_class *new_class)
{
@@ -636,7 +778,7 @@
if (!new_class->name)
return 0;
- list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
+ list_for_each_entry(class, &all_lock_classes, lock_entry) {
if (new_class->key - new_class->subclass == class->key)
return class->name_version;
if (class->name && !strcmp(class->name, new_class->name))
@@ -695,7 +837,8 @@
* Huh! same key, different name? Did someone trample
* on some memory? We're most confused.
*/
- WARN_ON_ONCE(class->name != lock->name);
+ WARN_ON_ONCE(class->name != lock->name &&
+ lock->key != &__lockdep_no_validate__);
return class;
}
}
@@ -712,6 +855,17 @@
{
unsigned long can_addr, addr = (unsigned long)lock;
+#ifdef __KERNEL__
+ /*
+ * lockdep_free_key_range() assumes that struct lock_class_key
+ * objects do not overlap. Since we use the address of lock
+ * objects as class key for static objects, check whether the
+ * size of lock_class_key objects does not exceed the size of
+ * the smallest lock object.
+ */
+ BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t));
+#endif
+
if (__is_kernel_percpu_address(addr, &can_addr))
lock->key = (void *)can_addr;
else if (__is_module_percpu_address(addr, &can_addr))
@@ -731,6 +885,289 @@
return true;
}
+#ifdef CONFIG_DEBUG_LOCKDEP
+
+/* Check whether element @e occurs in list @h */
+static bool in_list(struct list_head *e, struct list_head *h)
+{
+ struct list_head *f;
+
+ list_for_each(f, h) {
+ if (e == f)
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * Check whether entry @e occurs in any of the locks_after or locks_before
+ * lists.
+ */
+static bool in_any_class_list(struct list_head *e)
+{
+ struct lock_class *class;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
+ class = &lock_classes[i];
+ if (in_list(e, &class->locks_after) ||
+ in_list(e, &class->locks_before))
+ return true;
+ }
+ return false;
+}
+
+static bool class_lock_list_valid(struct lock_class *c, struct list_head *h)
+{
+ struct lock_list *e;
+
+ list_for_each_entry(e, h, entry) {
+ if (e->links_to != c) {
+ printk(KERN_INFO "class %s: mismatch for lock entry %ld; class %s <> %s",
+ c->name ? : "(?)",
+ (unsigned long)(e - list_entries),
+ e->links_to && e->links_to->name ?
+ e->links_to->name : "(?)",
+ e->class && e->class->name ? e->class->name :
+ "(?)");
+ return false;
+ }
+ }
+ return true;
+}
+
+#ifdef CONFIG_PROVE_LOCKING
+static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
+#endif
+
+static bool check_lock_chain_key(struct lock_chain *chain)
+{
+#ifdef CONFIG_PROVE_LOCKING
+ u64 chain_key = INITIAL_CHAIN_KEY;
+ int i;
+
+ for (i = chain->base; i < chain->base + chain->depth; i++)
+ chain_key = iterate_chain_key(chain_key, chain_hlocks[i]);
+ /*
+ * The 'unsigned long long' casts avoid that a compiler warning
+ * is reported when building tools/lib/lockdep.
+ */
+ if (chain->chain_key != chain_key) {
+ printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n",
+ (unsigned long long)(chain - lock_chains),
+ (unsigned long long)chain->chain_key,
+ (unsigned long long)chain_key);
+ return false;
+ }
+#endif
+ return true;
+}
+
+static bool in_any_zapped_class_list(struct lock_class *class)
+{
+ struct pending_free *pf;
+ int i;
+
+ for (i = 0, pf = delayed_free.pf; i < ARRAY_SIZE(delayed_free.pf); i++, pf++) {
+ if (in_list(&class->lock_entry, &pf->zapped))
+ return true;
+ }
+
+ return false;
+}
+
+static bool __check_data_structures(void)
+{
+ struct lock_class *class;
+ struct lock_chain *chain;
+ struct hlist_head *head;
+ struct lock_list *e;
+ int i;
+
+ /* Check whether all classes occur in a lock list. */
+ for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
+ class = &lock_classes[i];
+ if (!in_list(&class->lock_entry, &all_lock_classes) &&
+ !in_list(&class->lock_entry, &free_lock_classes) &&
+ !in_any_zapped_class_list(class)) {
+ printk(KERN_INFO "class %px/%s is not in any class list\n",
+ class, class->name ? : "(?)");
+ return false;
+ }
+ }
+
+ /* Check whether all classes have valid lock lists. */
+ for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
+ class = &lock_classes[i];
+ if (!class_lock_list_valid(class, &class->locks_before))
+ return false;
+ if (!class_lock_list_valid(class, &class->locks_after))
+ return false;
+ }
+
+ /* Check the chain_key of all lock chains. */
+ for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
+ head = chainhash_table + i;
+ hlist_for_each_entry_rcu(chain, head, entry) {
+ if (!check_lock_chain_key(chain))
+ return false;
+ }
+ }
+
+ /*
+ * Check whether all list entries that are in use occur in a class
+ * lock list.
+ */
+ for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
+ e = list_entries + i;
+ if (!in_any_class_list(&e->entry)) {
+ printk(KERN_INFO "list entry %d is not in any class list; class %s <> %s\n",
+ (unsigned int)(e - list_entries),
+ e->class->name ? : "(?)",
+ e->links_to->name ? : "(?)");
+ return false;
+ }
+ }
+
+ /*
+ * Check whether all list entries that are not in use do not occur in
+ * a class lock list.
+ */
+ for_each_clear_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
+ e = list_entries + i;
+ if (in_any_class_list(&e->entry)) {
+ printk(KERN_INFO "list entry %d occurs in a class list; class %s <> %s\n",
+ (unsigned int)(e - list_entries),
+ e->class && e->class->name ? e->class->name :
+ "(?)",
+ e->links_to && e->links_to->name ?
+ e->links_to->name : "(?)");
+ return false;
+ }
+ }
+
+ return true;
+}
+
+int check_consistency = 0;
+module_param(check_consistency, int, 0644);
+
+static void check_data_structures(void)
+{
+ static bool once = false;
+
+ if (check_consistency && !once) {
+ if (!__check_data_structures()) {
+ once = true;
+ WARN_ON(once);
+ }
+ }
+}
+
+#else /* CONFIG_DEBUG_LOCKDEP */
+
+static inline void check_data_structures(void) { }
+
+#endif /* CONFIG_DEBUG_LOCKDEP */
+
+/*
+ * Initialize the lock_classes[] array elements, the free_lock_classes list
+ * and also the delayed_free structure.
+ */
+static void init_data_structures_once(void)
+{
+ static bool ds_initialized, rcu_head_initialized;
+ int i;
+
+ if (likely(rcu_head_initialized))
+ return;
+
+ if (system_state >= SYSTEM_SCHEDULING) {
+ init_rcu_head(&delayed_free.rcu_head);
+ rcu_head_initialized = true;
+ }
+
+ if (ds_initialized)
+ return;
+
+ ds_initialized = true;
+
+ INIT_LIST_HEAD(&delayed_free.pf[0].zapped);
+ INIT_LIST_HEAD(&delayed_free.pf[1].zapped);
+
+ for (i = 0; i < ARRAY_SIZE(lock_classes); i++) {
+ list_add_tail(&lock_classes[i].lock_entry, &free_lock_classes);
+ INIT_LIST_HEAD(&lock_classes[i].locks_after);
+ INIT_LIST_HEAD(&lock_classes[i].locks_before);
+ }
+}
+
+static inline struct hlist_head *keyhashentry(const struct lock_class_key *key)
+{
+ unsigned long hash = hash_long((uintptr_t)key, KEYHASH_BITS);
+
+ return lock_keys_hash + hash;
+}
+
+/* Register a dynamically allocated key. */
+void lockdep_register_key(struct lock_class_key *key)
+{
+ struct hlist_head *hash_head;
+ struct lock_class_key *k;
+ unsigned long flags;
+
+ if (WARN_ON_ONCE(static_obj(key)))
+ return;
+ hash_head = keyhashentry(key);
+
+ raw_local_irq_save(flags);
+ if (!graph_lock())
+ goto restore_irqs;
+ hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
+ if (WARN_ON_ONCE(k == key))
+ goto out_unlock;
+ }
+ hlist_add_head_rcu(&key->hash_entry, hash_head);
+out_unlock:
+ graph_unlock();
+restore_irqs:
+ raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lockdep_register_key);
+
+/* Check whether a key has been registered as a dynamic key. */
+static bool is_dynamic_key(const struct lock_class_key *key)
+{
+ struct hlist_head *hash_head;
+ struct lock_class_key *k;
+ bool found = false;
+
+ if (WARN_ON_ONCE(static_obj(key)))
+ return false;
+
+ /*
+ * If lock debugging is disabled lock_keys_hash[] may contain
+ * pointers to memory that has already been freed. Avoid triggering
+ * a use-after-free in that case by returning early.
+ */
+ if (!debug_locks)
+ return true;
+
+ hash_head = keyhashentry(key);
+
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
+ if (k == key) {
+ found = true;
+ break;
+ }
+ }
+ rcu_read_unlock();
+
+ return found;
+}
+
/*
* Register a lock's class in the hash-table, if the class is not present
* yet. Otherwise we look it up. We cache the result in the lock object
@@ -752,7 +1189,7 @@
if (!lock->key) {
if (!assign_lock_key(lock))
return NULL;
- } else if (!static_obj(lock->key)) {
+ } else if (!static_obj(lock->key) && !is_dynamic_key(lock->key)) {
return NULL;
}
@@ -771,11 +1208,12 @@
goto out_unlock_set;
}
- /*
- * Allocate a new key from the static array, and add it to
- * the hash:
- */
- if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
+ init_data_structures_once();
+
+ /* Allocate a new lock class and add it to the hash. */
+ class = list_first_entry_or_null(&free_lock_classes, typeof(*class),
+ lock_entry);
+ if (!class) {
if (!debug_locks_off_graph_unlock()) {
return NULL;
}
@@ -784,14 +1222,14 @@
dump_stack();
return NULL;
}
- class = lock_classes + nr_lock_classes++;
+ nr_lock_classes++;
+ __set_bit(class - lock_classes, lock_classes_in_use);
debug_atomic_inc(nr_unused_locks);
class->key = key;
class->name = lock->name;
class->subclass = subclass;
- INIT_LIST_HEAD(&class->lock_entry);
- INIT_LIST_HEAD(&class->locks_before);
- INIT_LIST_HEAD(&class->locks_after);
+ WARN_ON_ONCE(!list_empty(&class->locks_before));
+ WARN_ON_ONCE(!list_empty(&class->locks_after));
class->name_version = count_matching_names(class);
/*
* We use RCU's safe list-add method to make
@@ -799,9 +1237,10 @@
*/
hlist_add_head_rcu(&class->hash_entry, hash_head);
/*
- * Add it to the global list of classes:
+ * Remove the class from the free list and add it to the global list
+ * of classes.
*/
- list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
+ list_move_tail(&class->lock_entry, &all_lock_classes);
if (verbose(class)) {
graph_unlock();
@@ -842,7 +1281,10 @@
*/
static struct lock_list *alloc_list_entry(void)
{
- if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
+ int idx = find_first_zero_bit(list_entries_in_use,
+ ARRAY_SIZE(list_entries));
+
+ if (idx >= ARRAY_SIZE(list_entries)) {
if (!debug_locks_off_graph_unlock())
return NULL;
@@ -850,15 +1292,18 @@
dump_stack();
return NULL;
}
- return list_entries + nr_list_entries++;
+ nr_list_entries++;
+ __set_bit(idx, list_entries_in_use);
+ return list_entries + idx;
}
/*
* Add a new dependency to the head of the list:
*/
-static int add_lock_to_list(struct lock_class *this, struct list_head *head,
+static int add_lock_to_list(struct lock_class *this,
+ struct lock_class *links_to, struct list_head *head,
unsigned long ip, int distance,
- struct stack_trace *trace)
+ const struct lock_trace *trace)
{
struct lock_list *entry;
/*
@@ -870,8 +1315,9 @@
return 0;
entry->class = this;
+ entry->links_to = links_to;
entry->distance = distance;
- entry->trace = *trace;
+ entry->trace = trace;
/*
* Both allocation and removal are done under the graph lock; but
* iteration is under RCU-sched; see look_up_lock_class() and
@@ -889,13 +1335,17 @@
#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
/*
- * The circular_queue and helpers is used to implement the
- * breadth-first search(BFS)algorithem, by which we can build
- * the shortest path from the next lock to be acquired to the
- * previous held lock if there is a circular between them.
+ * The circular_queue and helpers are used to implement graph
+ * breadth-first search (BFS) algorithm, by which we can determine
+ * whether there is a path from a lock to another. In deadlock checks,
+ * a path from the next lock to be acquired to a previous held lock
+ * indicates that adding the <prev> -> <next> lock dependency will
+ * produce a circle in the graph. Breadth-first search instead of
+ * depth-first search is used in order to find the shortest (circular)
+ * path.
*/
struct circular_queue {
- unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
+ struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE];
unsigned int front, rear;
};
@@ -921,7 +1371,7 @@
return ((cq->rear + 1) & CQ_MASK) == cq->front;
}
-static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
+static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem)
{
if (__cq_full(cq))
return -1;
@@ -931,14 +1381,21 @@
return 0;
}
-static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
+/*
+ * Dequeue an element from the circular_queue, return a lock_list if
+ * the queue is not empty, or NULL if otherwise.
+ */
+static inline struct lock_list * __cq_dequeue(struct circular_queue *cq)
{
- if (__cq_empty(cq))
- return -1;
+ struct lock_list * lock;
- *elem = cq->element[cq->front];
+ if (__cq_empty(cq))
+ return NULL;
+
+ lock = cq->element[cq->front];
cq->front = (cq->front + 1) & CQ_MASK;
- return 0;
+
+ return lock;
}
static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
@@ -952,7 +1409,7 @@
unsigned long nr;
nr = lock - list_entries;
- WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
+ WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */
lock->parent = parent;
lock->class->dep_gen_id = lockdep_dependency_gen_id;
}
@@ -962,7 +1419,7 @@
unsigned long nr;
nr = lock - list_entries;
- WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
+ WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */
return lock->class->dep_gen_id == lockdep_dependency_gen_id;
}
@@ -983,13 +1440,32 @@
return depth;
}
+/*
+ * Return the forward or backward dependency list.
+ *
+ * @lock: the lock_list to get its class's dependency list
+ * @offset: the offset to struct lock_class to determine whether it is
+ * locks_after or locks_before
+ */
+static inline struct list_head *get_dep_list(struct lock_list *lock, int offset)
+{
+ void *lock_class = lock->class;
+
+ return lock_class + offset;
+}
+
+/*
+ * Forward- or backward-dependency search, used for both circular dependency
+ * checking and hardirq-unsafe/softirq-unsafe checking.
+ */
static int __bfs(struct lock_list *source_entry,
void *data,
int (*match)(struct lock_list *entry, void *data),
struct lock_list **target_entry,
- int forward)
+ int offset)
{
struct lock_list *entry;
+ struct lock_list *lock;
struct list_head *head;
struct circular_queue *cq = &lock_cq;
int ret = 1;
@@ -1000,31 +1476,21 @@
goto exit;
}
- if (forward)
- head = &source_entry->class->locks_after;
- else
- head = &source_entry->class->locks_before;
-
+ head = get_dep_list(source_entry, offset);
if (list_empty(head))
goto exit;
__cq_init(cq);
- __cq_enqueue(cq, (unsigned long)source_entry);
+ __cq_enqueue(cq, source_entry);
- while (!__cq_empty(cq)) {
- struct lock_list *lock;
-
- __cq_dequeue(cq, (unsigned long *)&lock);
+ while ((lock = __cq_dequeue(cq))) {
if (!lock->class) {
ret = -2;
goto exit;
}
- if (forward)
- head = &lock->class->locks_after;
- else
- head = &lock->class->locks_before;
+ head = get_dep_list(lock, offset);
DEBUG_LOCKS_WARN_ON(!irqs_disabled());
@@ -1038,7 +1504,7 @@
goto exit;
}
- if (__cq_enqueue(cq, (unsigned long)entry)) {
+ if (__cq_enqueue(cq, entry)) {
ret = -1;
goto exit;
}
@@ -1057,7 +1523,8 @@
int (*match)(struct lock_list *entry, void *data),
struct lock_list **target_entry)
{
- return __bfs(src_entry, data, match, target_entry, 1);
+ return __bfs(src_entry, data, match, target_entry,
+ offsetof(struct lock_class, locks_after));
}
@@ -1066,31 +1533,30 @@
int (*match)(struct lock_list *entry, void *data),
struct lock_list **target_entry)
{
- return __bfs(src_entry, data, match, target_entry, 0);
+ return __bfs(src_entry, data, match, target_entry,
+ offsetof(struct lock_class, locks_before));
}
-/*
- * Recursive, forwards-direction lock-dependency checking, used for
- * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
- * checking.
- */
+static void print_lock_trace(const struct lock_trace *trace,
+ unsigned int spaces)
+{
+ stack_trace_print(trace->entries, trace->nr_entries, spaces);
+}
/*
* Print a dependency chain entry (this is only done when a deadlock
* has been detected):
*/
-static noinline int
+static noinline void
print_circular_bug_entry(struct lock_list *target, int depth)
{
if (debug_locks_silent)
- return 0;
+ return;
printk("\n-> #%u", depth);
print_lock_name(target->class);
printk(KERN_CONT ":\n");
- print_stack_trace(&target->trace, 6);
-
- return 0;
+ print_lock_trace(target->trace, 6);
}
static void
@@ -1147,7 +1613,7 @@
* When a circular dependency is detected, print the
* header first:
*/
-static noinline int
+static noinline void
print_circular_bug_header(struct lock_list *entry, unsigned int depth,
struct held_lock *check_src,
struct held_lock *check_tgt)
@@ -1155,7 +1621,7 @@
struct task_struct *curr = current;
if (debug_locks_silent)
- return 0;
+ return;
pr_warn("\n");
pr_warn("======================================================\n");
@@ -1173,8 +1639,6 @@
pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
print_circular_bug_entry(entry, depth);
-
- return 0;
}
static inline int class_equal(struct lock_list *entry, void *data)
@@ -1182,11 +1646,10 @@
return entry->class == data;
}
-static noinline int print_circular_bug(struct lock_list *this,
- struct lock_list *target,
- struct held_lock *check_src,
- struct held_lock *check_tgt,
- struct stack_trace *trace)
+static noinline void print_circular_bug(struct lock_list *this,
+ struct lock_list *target,
+ struct held_lock *check_src,
+ struct held_lock *check_tgt)
{
struct task_struct *curr = current;
struct lock_list *parent;
@@ -1194,10 +1657,11 @@
int depth;
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
- return 0;
+ return;
- if (!save_trace(&this->trace))
- return 0;
+ this->trace = save_trace();
+ if (!this->trace)
+ return;
depth = get_lock_depth(target);
@@ -1219,21 +1683,17 @@
printk("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}
-static noinline int print_bfs_bug(int ret)
+static noinline void print_bfs_bug(int ret)
{
if (!debug_locks_off_graph_unlock())
- return 0;
+ return;
/*
* Breadth-first-search failed, graph got corrupted?
*/
WARN(1, "lockdep bfs error:%d\n", ret);
-
- return 0;
}
static int noop_count(struct lock_list *entry, void *data)
@@ -1296,49 +1756,114 @@
}
/*
- * Prove that the dependency graph starting at <entry> can not
- * lead to <target>. Print an error and return 0 if it does.
+ * Check that the dependency graph starting at <src> can lead to
+ * <target> or not. Print an error and return 0 if it does.
*/
static noinline int
-check_noncircular(struct lock_list *root, struct lock_class *target,
- struct lock_list **target_entry)
+check_path(struct lock_class *target, struct lock_list *src_entry,
+ struct lock_list **target_entry)
{
- int result;
+ int ret;
+
+ ret = __bfs_forwards(src_entry, (void *)target, class_equal,
+ target_entry);
+
+ if (unlikely(ret < 0))
+ print_bfs_bug(ret);
+
+ return ret;
+}
+
+/*
+ * Prove that the dependency graph starting at <src> can not
+ * lead to <target>. If it can, there is a circle when adding
+ * <target> -> <src> dependency.
+ *
+ * Print an error and return 0 if it does.
+ */
+static noinline int
+check_noncircular(struct held_lock *src, struct held_lock *target,
+ struct lock_trace **const trace)
+{
+ int ret;
+ struct lock_list *uninitialized_var(target_entry);
+ struct lock_list src_entry = {
+ .class = hlock_class(src),
+ .parent = NULL,
+ };
debug_atomic_inc(nr_cyclic_checks);
- result = __bfs_forwards(root, target, class_equal, target_entry);
+ ret = check_path(hlock_class(target), &src_entry, &target_entry);
- return result;
+ if (unlikely(!ret)) {
+ if (!*trace) {
+ /*
+ * If save_trace fails here, the printing might
+ * trigger a WARN but because of the !nr_entries it
+ * should not do bad things.
+ */
+ *trace = save_trace();
+ }
+
+ print_circular_bug(&src_entry, target_entry, src, target);
+ }
+
+ return ret;
}
+#ifdef CONFIG_LOCKDEP_SMALL
+/*
+ * Check that the dependency graph starting at <src> can lead to
+ * <target> or not. If it can, <src> -> <target> dependency is already
+ * in the graph.
+ *
+ * Print an error and return 2 if it does or 1 if it does not.
+ */
static noinline int
-check_redundant(struct lock_list *root, struct lock_class *target,
- struct lock_list **target_entry)
+check_redundant(struct held_lock *src, struct held_lock *target)
{
- int result;
+ int ret;
+ struct lock_list *uninitialized_var(target_entry);
+ struct lock_list src_entry = {
+ .class = hlock_class(src),
+ .parent = NULL,
+ };
debug_atomic_inc(nr_redundant_checks);
- result = __bfs_forwards(root, target, class_equal, target_entry);
+ ret = check_path(hlock_class(target), &src_entry, &target_entry);
- return result;
+ if (!ret) {
+ debug_atomic_inc(nr_redundant);
+ ret = 2;
+ } else if (ret < 0)
+ ret = 0;
+
+ return ret;
+}
+#endif
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+
+static inline int usage_accumulate(struct lock_list *entry, void *mask)
+{
+ *(unsigned long *)mask |= entry->class->usage_mask;
+
+ return 0;
}
-#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
/*
* Forwards and backwards subgraph searching, for the purposes of
* proving that two subgraphs can be connected by a new dependency
* without creating any illegal irq-safe -> irq-unsafe lock dependency.
*/
-static inline int usage_match(struct lock_list *entry, void *bit)
+static inline int usage_match(struct lock_list *entry, void *mask)
{
- return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
+ return entry->class->usage_mask & *(unsigned long *)mask;
}
-
-
/*
* Find a node in the forwards-direction dependency sub-graph starting
* at @root->class that matches @bit.
@@ -1350,14 +1875,14 @@
* Return <0 on error.
*/
static int
-find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
+find_usage_forwards(struct lock_list *root, unsigned long usage_mask,
struct lock_list **target_entry)
{
int result;
debug_atomic_inc(nr_find_usage_forwards_checks);
- result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
+ result = __bfs_forwards(root, &usage_mask, usage_match, target_entry);
return result;
}
@@ -1373,14 +1898,14 @@
* Return <0 on error.
*/
static int
-find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
+find_usage_backwards(struct lock_list *root, unsigned long usage_mask,
struct lock_list **target_entry)
{
int result;
debug_atomic_inc(nr_find_usage_backwards_checks);
- result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
+ result = __bfs_backwards(root, &usage_mask, usage_match, target_entry);
return result;
}
@@ -1391,7 +1916,9 @@
printk("%*s->", depth, "");
print_lock_name(class);
- printk(KERN_CONT " ops: %lu", class->ops);
+#ifdef CONFIG_DEBUG_LOCKDEP
+ printk(KERN_CONT " ops: %lu", debug_class_ops_read(class));
+#endif
printk(KERN_CONT " {\n");
for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
@@ -1400,7 +1927,7 @@
len += printk("%*s %s", depth, "", usage_str[bit]);
len += printk(KERN_CONT " at:\n");
- print_stack_trace(class->usage_traces + bit, len);
+ print_lock_trace(class->usage_traces[bit], len);
}
}
printk("%*s }\n", depth, "");
@@ -1414,7 +1941,7 @@
*/
static void __used
print_shortest_lock_dependencies(struct lock_list *leaf,
- struct lock_list *root)
+ struct lock_list *root)
{
struct lock_list *entry = leaf;
int depth;
@@ -1425,7 +1952,7 @@
do {
print_lock_class_header(entry->class, depth);
printk("%*s ... acquired at:\n", depth, "");
- print_stack_trace(&entry->trace, 2);
+ print_lock_trace(entry->trace, 2);
printk("\n");
if (depth == 0 && (entry != root)) {
@@ -1436,8 +1963,6 @@
entry = get_lock_parent(entry);
depth--;
} while (entry && (depth >= 0));
-
- return;
}
static void
@@ -1496,7 +2021,7 @@
printk("\n *** DEADLOCK ***\n\n");
}
-static int
+static void
print_bad_irq_dependency(struct task_struct *curr,
struct lock_list *prev_root,
struct lock_list *next_root,
@@ -1509,7 +2034,7 @@
const char *irqclass)
{
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
- return 0;
+ return;
pr_warn("\n");
pr_warn("=====================================================\n");
@@ -1538,14 +2063,14 @@
print_lock_name(backwards_entry->class);
pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
- print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
+ print_lock_trace(backwards_entry->class->usage_traces[bit1], 1);
pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
print_lock_name(forwards_entry->class);
pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
pr_warn("...");
- print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
+ print_lock_trace(forwards_entry->class->usage_traces[bit2], 1);
pr_warn("\nother info that might help us debug this:\n\n");
print_irq_lock_scenario(backwards_entry, forwards_entry,
@@ -1554,53 +2079,20 @@
lockdep_print_held_locks(curr);
pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
- if (!save_trace(&prev_root->trace))
- return 0;
+ prev_root->trace = save_trace();
+ if (!prev_root->trace)
+ return;
print_shortest_lock_dependencies(backwards_entry, prev_root);
pr_warn("\nthe dependencies between the lock to be acquired");
pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
- if (!save_trace(&next_root->trace))
- return 0;
+ next_root->trace = save_trace();
+ if (!next_root->trace)
+ return;
print_shortest_lock_dependencies(forwards_entry, next_root);
pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
-}
-
-static int
-check_usage(struct task_struct *curr, struct held_lock *prev,
- struct held_lock *next, enum lock_usage_bit bit_backwards,
- enum lock_usage_bit bit_forwards, const char *irqclass)
-{
- int ret;
- struct lock_list this, that;
- struct lock_list *uninitialized_var(target_entry);
- struct lock_list *uninitialized_var(target_entry1);
-
- this.parent = NULL;
-
- this.class = hlock_class(prev);
- ret = find_usage_backwards(&this, bit_backwards, &target_entry);
- if (ret < 0)
- return print_bfs_bug(ret);
- if (ret == 1)
- return ret;
-
- that.parent = NULL;
- that.class = hlock_class(next);
- ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
- if (ret < 0)
- return print_bfs_bug(ret);
- if (ret == 1)
- return ret;
-
- return print_bad_irq_dependency(curr, &this, &that,
- target_entry, target_entry1,
- prev, next,
- bit_backwards, bit_forwards, irqclass);
}
static const char *state_names[] = {
@@ -1619,70 +2111,192 @@
static inline const char *state_name(enum lock_usage_bit bit)
{
- return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
+ if (bit & LOCK_USAGE_READ_MASK)
+ return state_rnames[bit >> LOCK_USAGE_DIR_MASK];
+ else
+ return state_names[bit >> LOCK_USAGE_DIR_MASK];
}
+/*
+ * The bit number is encoded like:
+ *
+ * bit0: 0 exclusive, 1 read lock
+ * bit1: 0 used in irq, 1 irq enabled
+ * bit2-n: state
+ */
static int exclusive_bit(int new_bit)
{
- /*
- * USED_IN
- * USED_IN_READ
- * ENABLED
- * ENABLED_READ
- *
- * bit 0 - write/read
- * bit 1 - used_in/enabled
- * bit 2+ state
- */
-
- int state = new_bit & ~3;
- int dir = new_bit & 2;
+ int state = new_bit & LOCK_USAGE_STATE_MASK;
+ int dir = new_bit & LOCK_USAGE_DIR_MASK;
/*
* keep state, bit flip the direction and strip read.
*/
- return state | (dir ^ 2);
+ return state | (dir ^ LOCK_USAGE_DIR_MASK);
}
+/*
+ * Observe that when given a bitmask where each bitnr is encoded as above, a
+ * right shift of the mask transforms the individual bitnrs as -1 and
+ * conversely, a left shift transforms into +1 for the individual bitnrs.
+ *
+ * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can
+ * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0)
+ * instead by subtracting the bit number by 2, or shifting the mask right by 2.
+ *
+ * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2.
+ *
+ * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is
+ * all bits set) and recompose with bitnr1 flipped.
+ */
+static unsigned long invert_dir_mask(unsigned long mask)
+{
+ unsigned long excl = 0;
+
+ /* Invert dir */
+ excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK;
+ excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK;
+
+ return excl;
+}
+
+/*
+ * As above, we clear bitnr0 (LOCK_*_READ off) with bitmask ops. First, for all
+ * bits with bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*).
+ * And then mask out all bitnr0.
+ */
+static unsigned long exclusive_mask(unsigned long mask)
+{
+ unsigned long excl = invert_dir_mask(mask);
+
+ /* Strip read */
+ excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK;
+ excl &= ~LOCKF_IRQ_READ;
+
+ return excl;
+}
+
+/*
+ * Retrieve the _possible_ original mask to which @mask is
+ * exclusive. Ie: this is the opposite of exclusive_mask().
+ * Note that 2 possible original bits can match an exclusive
+ * bit: one has LOCK_USAGE_READ_MASK set, the other has it
+ * cleared. So both are returned for each exclusive bit.
+ */
+static unsigned long original_mask(unsigned long mask)
+{
+ unsigned long excl = invert_dir_mask(mask);
+
+ /* Include read in existing usages */
+ excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK;
+
+ return excl;
+}
+
+/*
+ * Find the first pair of bit match between an original
+ * usage mask and an exclusive usage mask.
+ */
+static int find_exclusive_match(unsigned long mask,
+ unsigned long excl_mask,
+ enum lock_usage_bit *bitp,
+ enum lock_usage_bit *excl_bitp)
+{
+ int bit, excl;
+
+ for_each_set_bit(bit, &mask, LOCK_USED) {
+ excl = exclusive_bit(bit);
+ if (excl_mask & lock_flag(excl)) {
+ *bitp = bit;
+ *excl_bitp = excl;
+ return 0;
+ }
+ }
+ return -1;
+}
+
+/*
+ * Prove that the new dependency does not connect a hardirq-safe(-read)
+ * lock with a hardirq-unsafe lock - to achieve this we search
+ * the backwards-subgraph starting at <prev>, and the
+ * forwards-subgraph starting at <next>:
+ */
static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
- struct held_lock *next, enum lock_usage_bit bit)
+ struct held_lock *next)
{
- /*
- * Prove that the new dependency does not connect a hardirq-safe
- * lock with a hardirq-unsafe lock - to achieve this we search
- * the backwards-subgraph starting at <prev>, and the
- * forwards-subgraph starting at <next>:
- */
- if (!check_usage(curr, prev, next, bit,
- exclusive_bit(bit), state_name(bit)))
- return 0;
-
- bit++; /* _READ */
+ unsigned long usage_mask = 0, forward_mask, backward_mask;
+ enum lock_usage_bit forward_bit = 0, backward_bit = 0;
+ struct lock_list *uninitialized_var(target_entry1);
+ struct lock_list *uninitialized_var(target_entry);
+ struct lock_list this, that;
+ int ret;
/*
- * Prove that the new dependency does not connect a hardirq-safe-read
- * lock with a hardirq-unsafe lock - to achieve this we search
- * the backwards-subgraph starting at <prev>, and the
- * forwards-subgraph starting at <next>:
+ * Step 1: gather all hard/soft IRQs usages backward in an
+ * accumulated usage mask.
*/
- if (!check_usage(curr, prev, next, bit,
- exclusive_bit(bit), state_name(bit)))
+ this.parent = NULL;
+ this.class = hlock_class(prev);
+
+ ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, NULL);
+ if (ret < 0) {
+ print_bfs_bug(ret);
return 0;
+ }
- return 1;
-}
+ usage_mask &= LOCKF_USED_IN_IRQ_ALL;
+ if (!usage_mask)
+ return 1;
-static int
-check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
- struct held_lock *next)
-{
-#define LOCKDEP_STATE(__STATE) \
- if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
+ /*
+ * Step 2: find exclusive uses forward that match the previous
+ * backward accumulated mask.
+ */
+ forward_mask = exclusive_mask(usage_mask);
+
+ that.parent = NULL;
+ that.class = hlock_class(next);
+
+ ret = find_usage_forwards(&that, forward_mask, &target_entry1);
+ if (ret < 0) {
+ print_bfs_bug(ret);
return 0;
-#include "lockdep_states.h"
-#undef LOCKDEP_STATE
+ }
+ if (ret == 1)
+ return ret;
- return 1;
+ /*
+ * Step 3: we found a bad match! Now retrieve a lock from the backward
+ * list whose usage mask matches the exclusive usage mask from the
+ * lock found on the forward list.
+ */
+ backward_mask = original_mask(target_entry1->class->usage_mask);
+
+ ret = find_usage_backwards(&this, backward_mask, &target_entry);
+ if (ret < 0) {
+ print_bfs_bug(ret);
+ return 0;
+ }
+ if (DEBUG_LOCKS_WARN_ON(ret == 1))
+ return 1;
+
+ /*
+ * Step 4: narrow down to a pair of incompatible usage bits
+ * and report it.
+ */
+ ret = find_exclusive_match(target_entry->class->usage_mask,
+ target_entry1->class->usage_mask,
+ &backward_bit, &forward_bit);
+ if (DEBUG_LOCKS_WARN_ON(ret == -1))
+ return 1;
+
+ print_bad_irq_dependency(curr, &this, &that,
+ target_entry, target_entry1,
+ prev, next,
+ backward_bit, forward_bit,
+ state_name(backward_bit));
+
+ return 0;
}
static void inc_chains(void)
@@ -1699,9 +2313,8 @@
#else
-static inline int
-check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
- struct held_lock *next)
+static inline int check_irq_usage(struct task_struct *curr,
+ struct held_lock *prev, struct held_lock *next)
{
return 1;
}
@@ -1711,11 +2324,10 @@
nr_process_chains++;
}
-#endif
+#endif /* CONFIG_TRACE_IRQFLAGS */
static void
-print_deadlock_scenario(struct held_lock *nxt,
- struct held_lock *prv)
+print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
{
struct lock_class *next = hlock_class(nxt);
struct lock_class *prev = hlock_class(prv);
@@ -1733,12 +2345,12 @@
printk(" May be due to missing lock nesting notation\n\n");
}
-static int
+static void
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
struct held_lock *next)
{
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
- return 0;
+ return;
pr_warn("\n");
pr_warn("============================================\n");
@@ -1757,8 +2369,6 @@
pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}
/*
@@ -1770,8 +2380,7 @@
* Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
*/
static int
-check_deadlock(struct task_struct *curr, struct held_lock *next,
- struct lockdep_map *next_instance, int read)
+check_deadlock(struct task_struct *curr, struct held_lock *next)
{
struct held_lock *prev;
struct held_lock *nest = NULL;
@@ -1790,7 +2399,7 @@
* Allow read-after-read recursion of the same
* lock class (i.e. read_lock(lock)+read_lock(lock)):
*/
- if ((read == 2) && prev->read)
+ if ((next->read == 2) && prev->read)
return 2;
/*
@@ -1800,14 +2409,15 @@
if (nest)
return 2;
- return print_deadlock_bug(curr, prev, next);
+ print_deadlock_bug(curr, prev, next);
+ return 0;
}
return 1;
}
/*
* There was a chain-cache miss, and we are about to add a new dependency
- * to a previous lock. We recursively validate the following rules:
+ * to a previous lock. We validate the following rules:
*
* - would the adding of the <prev> -> <next> dependency create a
* circular dependency in the graph? [== circular deadlock]
@@ -1829,41 +2439,45 @@
*/
static int
check_prev_add(struct task_struct *curr, struct held_lock *prev,
- struct held_lock *next, int distance, struct stack_trace *trace,
- int (*save)(struct stack_trace *trace))
+ struct held_lock *next, int distance,
+ struct lock_trace **const trace)
{
- struct lock_list *uninitialized_var(target_entry);
struct lock_list *entry;
- struct lock_list this;
int ret;
+ if (!hlock_class(prev)->key || !hlock_class(next)->key) {
+ /*
+ * The warning statements below may trigger a use-after-free
+ * of the class name. It is better to trigger a use-after free
+ * and to have the class name most of the time instead of not
+ * having the class name available.
+ */
+ WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key,
+ "Detected use-after-free of lock class %px/%s\n",
+ hlock_class(prev),
+ hlock_class(prev)->name);
+ WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key,
+ "Detected use-after-free of lock class %px/%s\n",
+ hlock_class(next),
+ hlock_class(next)->name);
+ return 2;
+ }
+
/*
* Prove that the new <prev> -> <next> dependency would not
* create a circular dependency in the graph. (We do this by
- * forward-recursing into the graph starting at <next>, and
- * checking whether we can reach <prev>.)
+ * a breadth-first search into the graph starting at <next>,
+ * and check whether we can reach <prev>.)
*
- * We are using global variables to control the recursion, to
- * keep the stackframe size of the recursive functions low:
+ * The search is limited by the size of the circular queue (i.e.,
+ * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes
+ * in the graph whose neighbours are to be checked.
*/
- this.class = hlock_class(next);
- this.parent = NULL;
- ret = check_noncircular(&this, hlock_class(prev), &target_entry);
- if (unlikely(!ret)) {
- if (!trace->entries) {
- /*
- * If @save fails here, the printing might trigger
- * a WARN but because of the !nr_entries it should
- * not do bad things.
- */
- save(trace);
- }
- return print_circular_bug(&this, target_entry, next, prev, trace);
- }
- else if (unlikely(ret < 0))
- return print_bfs_bug(ret);
+ ret = check_noncircular(next, prev, trace);
+ if (unlikely(ret <= 0))
+ return 0;
- if (!check_prev_add_irq(curr, prev, next))
+ if (!check_irq_usage(curr, prev, next))
return 0;
/*
@@ -1892,37 +2506,35 @@
}
}
+#ifdef CONFIG_LOCKDEP_SMALL
/*
* Is the <prev> -> <next> link redundant?
*/
- this.class = hlock_class(prev);
- this.parent = NULL;
- ret = check_redundant(&this, hlock_class(next), &target_entry);
- if (!ret) {
- debug_atomic_inc(nr_redundant);
- return 2;
+ ret = check_redundant(prev, next);
+ if (ret != 1)
+ return ret;
+#endif
+
+ if (!*trace) {
+ *trace = save_trace();
+ if (!*trace)
+ return 0;
}
- if (ret < 0)
- return print_bfs_bug(ret);
-
-
- if (!trace->entries && !save(trace))
- return 0;
/*
* Ok, all validations passed, add the new lock
* to the previous lock's dependency list:
*/
- ret = add_lock_to_list(hlock_class(next),
+ ret = add_lock_to_list(hlock_class(next), hlock_class(prev),
&hlock_class(prev)->locks_after,
- next->acquire_ip, distance, trace);
+ next->acquire_ip, distance, *trace);
if (!ret)
return 0;
- ret = add_lock_to_list(hlock_class(prev),
+ ret = add_lock_to_list(hlock_class(prev), hlock_class(next),
&hlock_class(next)->locks_before,
- next->acquire_ip, distance, trace);
+ next->acquire_ip, distance, *trace);
if (!ret)
return 0;
@@ -1938,14 +2550,9 @@
static int
check_prevs_add(struct task_struct *curr, struct held_lock *next)
{
+ struct lock_trace *trace = NULL;
int depth = curr->lockdep_depth;
struct held_lock *hlock;
- struct stack_trace trace = {
- .nr_entries = 0,
- .max_entries = 0,
- .entries = NULL,
- .skip = 0,
- };
/*
* Debugging checks.
@@ -1971,7 +2578,8 @@
* added:
*/
if (hlock->read != 2 && hlock->check) {
- int ret = check_prev_add(curr, hlock, next, distance, &trace, save_trace);
+ int ret = check_prev_add(curr, hlock, next, distance,
+ &trace);
if (!ret)
return 0;
@@ -2013,8 +2621,8 @@
return 0;
}
-unsigned long nr_lock_chains;
struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
+static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS);
int nr_chain_hlocks;
static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
@@ -2060,12 +2668,13 @@
print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
{
struct held_lock *hlock;
- u64 chain_key = 0;
+ u64 chain_key = INITIAL_CHAIN_KEY;
int depth = curr->lockdep_depth;
- int i;
+ int i = get_first_held_lock(curr, hlock_next);
- printk("depth: %u\n", depth + 1);
- for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
+ printk("depth: %u (irq_context %u)\n", depth - i + 1,
+ hlock_next->irq_context);
+ for (; i < depth; i++) {
hlock = curr->held_locks + i;
chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
@@ -2079,13 +2688,13 @@
static void print_chain_keys_chain(struct lock_chain *chain)
{
int i;
- u64 chain_key = 0;
+ u64 chain_key = INITIAL_CHAIN_KEY;
int class_id;
printk("depth: %u\n", chain->depth);
for (i = 0; i < chain->depth; i++) {
class_id = chain_hlocks[chain->base + i];
- chain_key = print_chain_key_iteration(class_id + 1, chain_key);
+ chain_key = print_chain_key_iteration(class_id, chain_key);
print_lock_name(lock_classes + class_id);
printk("\n");
@@ -2136,7 +2745,7 @@
}
for (j = 0; j < chain->depth - 1; j++, i++) {
- id = curr->held_locks[i].class_idx - 1;
+ id = curr->held_locks[i].class_idx;
if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
print_collision(curr, hlock, chain);
@@ -2148,73 +2757,30 @@
}
/*
- * This is for building a chain between just two different classes,
- * instead of adding a new hlock upon current, which is done by
- * add_chain_cache().
- *
- * This can be called in any context with two classes, while
- * add_chain_cache() must be done within the lock owener's context
- * since it uses hlock which might be racy in another context.
+ * Given an index that is >= -1, return the index of the next lock chain.
+ * Return -2 if there is no next lock chain.
*/
-static inline int add_chain_cache_classes(unsigned int prev,
- unsigned int next,
- unsigned int irq_context,
- u64 chain_key)
+long lockdep_next_lockchain(long i)
{
- struct hlist_head *hash_head = chainhashentry(chain_key);
- struct lock_chain *chain;
+ i = find_next_bit(lock_chains_in_use, ARRAY_SIZE(lock_chains), i + 1);
+ return i < ARRAY_SIZE(lock_chains) ? i : -2;
+}
- /*
- * Allocate a new chain entry from the static array, and add
- * it to the hash:
- */
+unsigned long lock_chain_count(void)
+{
+ return bitmap_weight(lock_chains_in_use, ARRAY_SIZE(lock_chains));
+}
- /*
- * We might need to take the graph lock, ensure we've got IRQs
- * disabled to make this an IRQ-safe lock.. for recursion reasons
- * lockdep won't complain about its own locking errors.
- */
- if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
- return 0;
+/* Must be called with the graph lock held. */
+static struct lock_chain *alloc_lock_chain(void)
+{
+ int idx = find_first_zero_bit(lock_chains_in_use,
+ ARRAY_SIZE(lock_chains));
- if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
- if (!debug_locks_off_graph_unlock())
- return 0;
-
- print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
- dump_stack();
- return 0;
- }
-
- chain = lock_chains + nr_lock_chains++;
- chain->chain_key = chain_key;
- chain->irq_context = irq_context;
- chain->depth = 2;
- if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
- chain->base = nr_chain_hlocks;
- nr_chain_hlocks += chain->depth;
- chain_hlocks[chain->base] = prev - 1;
- chain_hlocks[chain->base + 1] = next -1;
- }
-#ifdef CONFIG_DEBUG_LOCKDEP
- /*
- * Important for check_no_collision().
- */
- else {
- if (!debug_locks_off_graph_unlock())
- return 0;
-
- print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
- dump_stack();
- return 0;
- }
-#endif
-
- hlist_add_head_rcu(&chain->entry, hash_head);
- debug_atomic_inc(chain_lookup_misses);
- inc_chains();
-
- return 1;
+ if (unlikely(idx >= ARRAY_SIZE(lock_chains)))
+ return NULL;
+ __set_bit(idx, lock_chains_in_use);
+ return lock_chains + idx;
}
/*
@@ -2234,19 +2800,15 @@
int i, j;
/*
- * Allocate a new chain entry from the static array, and add
- * it to the hash:
- */
-
- /*
- * We might need to take the graph lock, ensure we've got IRQs
+ * The caller must hold the graph lock, ensure we've got IRQs
* disabled to make this an IRQ-safe lock.. for recursion reasons
* lockdep won't complain about its own locking errors.
*/
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return 0;
- if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
+ chain = alloc_lock_chain();
+ if (!chain) {
if (!debug_locks_off_graph_unlock())
return 0;
@@ -2254,7 +2816,6 @@
dump_stack();
return 0;
}
- chain = lock_chains + nr_lock_chains++;
chain->chain_key = chain_key;
chain->irq_context = hlock->irq_context;
i = get_first_held_lock(curr, hlock);
@@ -2267,20 +2828,12 @@
if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
chain->base = nr_chain_hlocks;
for (j = 0; j < chain->depth - 1; j++, i++) {
- int lock_id = curr->held_locks[i].class_idx - 1;
+ int lock_id = curr->held_locks[i].class_idx;
chain_hlocks[chain->base + j] = lock_id;
}
chain_hlocks[chain->base + j] = class - lock_classes;
- }
-
- if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
nr_chain_hlocks += chain->depth;
-
-#ifdef CONFIG_DEBUG_LOCKDEP
- /*
- * Important for check_no_collision().
- */
- if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
+ } else {
if (!debug_locks_off_graph_unlock())
return 0;
@@ -2288,7 +2841,6 @@
dump_stack();
return 0;
}
-#endif
hlist_add_head_rcu(&chain->entry, hash_head);
debug_atomic_inc(chain_lookup_misses);
@@ -2298,19 +2850,16 @@
}
/*
- * Look up a dependency chain.
+ * Look up a dependency chain. Must be called with either the graph lock or
+ * the RCU read lock held.
*/
static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
{
struct hlist_head *hash_head = chainhashentry(chain_key);
struct lock_chain *chain;
- /*
- * We can walk it lock-free, because entries only get added
- * to the hash:
- */
hlist_for_each_entry_rcu(chain, hash_head, entry) {
- if (chain->chain_key == chain_key) {
+ if (READ_ONCE(chain->chain_key) == chain_key) {
debug_atomic_inc(chain_lookup_hits);
return chain;
}
@@ -2369,8 +2918,9 @@
return 1;
}
-static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
- struct held_lock *hlock, int chain_head, u64 chain_key)
+static int validate_chain(struct task_struct *curr,
+ struct held_lock *hlock,
+ int chain_head, u64 chain_key)
{
/*
* Trylock needs to maintain the stack of held locks, but it
@@ -2391,12 +2941,18 @@
* - is softirq-safe, if this lock is hardirq-unsafe
*
* And check whether the new lock's dependency graph
- * could lead back to the previous lock.
+ * could lead back to the previous lock:
*
- * any of these scenarios could lead to a deadlock. If
- * All validations
+ * - within the current held-lock stack
+ * - across our accumulated lock dependency records
+ *
+ * any of these scenarios could lead to a deadlock.
*/
- int ret = check_deadlock(curr, hlock, lock, hlock->read);
+ /*
+ * The simple case: does the current hold the same lock
+ * already?
+ */
+ int ret = check_deadlock(curr, hlock);
if (!ret)
return 0;
@@ -2427,12 +2983,12 @@
}
#else
static inline int validate_chain(struct task_struct *curr,
- struct lockdep_map *lock, struct held_lock *hlock,
- int chain_head, u64 chain_key)
+ struct held_lock *hlock,
+ int chain_head, u64 chain_key)
{
return 1;
}
-#endif
+#endif /* CONFIG_PROVE_LOCKING */
/*
* We are building curr_chain_key incrementally, so double-check
@@ -2443,7 +2999,7 @@
#ifdef CONFIG_DEBUG_LOCKDEP
struct held_lock *hlock, *prev_hlock = NULL;
unsigned int i;
- u64 chain_key = 0;
+ u64 chain_key = INITIAL_CHAIN_KEY;
for (i = 0; i < curr->lockdep_depth; i++) {
hlock = curr->held_locks + i;
@@ -2459,15 +3015,17 @@
(unsigned long long)hlock->prev_chain_key);
return;
}
+
/*
- * Whoops ran out of static storage again?
+ * hlock->class_idx can't go beyond MAX_LOCKDEP_KEYS, but is
+ * it registered lock class index?
*/
- if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
+ if (DEBUG_LOCKS_WARN_ON(!test_bit(hlock->class_idx, lock_classes_in_use)))
return;
if (prev_hlock && (prev_hlock->irq_context !=
hlock->irq_context))
- chain_key = 0;
+ chain_key = INITIAL_CHAIN_KEY;
chain_key = iterate_chain_key(chain_key, hlock->class_idx);
prev_hlock = hlock;
}
@@ -2485,8 +3043,11 @@
#endif
}
-static void
-print_usage_bug_scenario(struct held_lock *lock)
+#ifdef CONFIG_PROVE_LOCKING
+static int mark_lock(struct task_struct *curr, struct held_lock *this,
+ enum lock_usage_bit new_bit);
+
+static void print_usage_bug_scenario(struct held_lock *lock)
{
struct lock_class *class = hlock_class(lock);
@@ -2503,12 +3064,12 @@
printk("\n *** DEADLOCK ***\n\n");
}
-static int
+static void
print_usage_bug(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
{
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
- return 0;
+ return;
pr_warn("\n");
pr_warn("================================\n");
@@ -2528,7 +3089,7 @@
print_lock(this);
pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
- print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
+ print_lock_trace(hlock_class(this)->usage_traces[prev_bit], 1);
print_irqtrace_events(curr);
pr_warn("\nother info that might help us debug this:\n");
@@ -2538,8 +3099,6 @@
pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}
/*
@@ -2549,20 +3108,18 @@
valid_state(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
{
- if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
- return print_usage_bug(curr, this, bad_bit, new_bit);
+ if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) {
+ print_usage_bug(curr, this, bad_bit, new_bit);
+ return 0;
+ }
return 1;
}
-static int mark_lock(struct task_struct *curr, struct held_lock *this,
- enum lock_usage_bit new_bit);
-
-#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
/*
* print irq inversion bug:
*/
-static int
+static void
print_irq_inversion_bug(struct task_struct *curr,
struct lock_list *root, struct lock_list *other,
struct held_lock *this, int forwards,
@@ -2573,7 +3130,7 @@
int depth;
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
- return 0;
+ return;
pr_warn("\n");
pr_warn("========================================================\n");
@@ -2613,14 +3170,13 @@
lockdep_print_held_locks(curr);
pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
- if (!save_trace(&root->trace))
- return 0;
+ root->trace = save_trace();
+ if (!root->trace)
+ return;
print_shortest_lock_dependencies(other, root);
pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}
/*
@@ -2637,14 +3193,17 @@
root.parent = NULL;
root.class = hlock_class(this);
- ret = find_usage_forwards(&root, bit, &target_entry);
- if (ret < 0)
- return print_bfs_bug(ret);
+ ret = find_usage_forwards(&root, lock_flag(bit), &target_entry);
+ if (ret < 0) {
+ print_bfs_bug(ret);
+ return 0;
+ }
if (ret == 1)
return ret;
- return print_irq_inversion_bug(curr, &root, target_entry,
- this, 1, irqclass);
+ print_irq_inversion_bug(curr, &root, target_entry,
+ this, 1, irqclass);
+ return 0;
}
/*
@@ -2661,14 +3220,17 @@
root.parent = NULL;
root.class = hlock_class(this);
- ret = find_usage_backwards(&root, bit, &target_entry);
- if (ret < 0)
- return print_bfs_bug(ret);
+ ret = find_usage_backwards(&root, lock_flag(bit), &target_entry);
+ if (ret < 0) {
+ print_bfs_bug(ret);
+ return 0;
+ }
if (ret == 1)
return ret;
- return print_irq_inversion_bug(curr, &root, target_entry,
- this, 0, irqclass);
+ print_irq_inversion_bug(curr, &root, target_entry,
+ this, 0, irqclass);
+ return 0;
}
void print_irqtrace_events(struct task_struct *curr)
@@ -2716,7 +3278,7 @@
static inline int state_verbose(enum lock_usage_bit bit,
struct lock_class *class)
{
- return state_verbose_f[bit >> 2](class);
+ return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class);
}
typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
@@ -2727,8 +3289,8 @@
enum lock_usage_bit new_bit)
{
int excl_bit = exclusive_bit(new_bit);
- int read = new_bit & 1;
- int dir = new_bit & 2;
+ int read = new_bit & LOCK_USAGE_READ_MASK;
+ int dir = new_bit & LOCK_USAGE_DIR_MASK;
/*
* mark USED_IN has to look forwards -- to ensure no dependency
@@ -2751,20 +3313,20 @@
* Validate that the lock dependencies don't have conflicting usage
* states.
*/
- if ((!read || !dir || STRICT_READ_CHECKS) &&
- !usage(curr, this, excl_bit, state_name(new_bit & ~1)))
+ if ((!read || STRICT_READ_CHECKS) &&
+ !usage(curr, this, excl_bit, state_name(new_bit & ~LOCK_USAGE_READ_MASK)))
return 0;
/*
* Check for read in write conflicts
*/
if (!read) {
- if (!valid_state(curr, this, new_bit, excl_bit + 1))
+ if (!valid_state(curr, this, new_bit, excl_bit + LOCK_USAGE_READ_MASK))
return 0;
if (STRICT_READ_CHECKS &&
- !usage(curr, this, excl_bit + 1,
- state_name(new_bit + 1)))
+ !usage(curr, this, excl_bit + LOCK_USAGE_READ_MASK,
+ state_name(new_bit + LOCK_USAGE_READ_MASK)))
return 0;
}
@@ -2774,35 +3336,28 @@
return 1;
}
-enum mark_type {
-#define LOCKDEP_STATE(__STATE) __STATE,
-#include "lockdep_states.h"
-#undef LOCKDEP_STATE
-};
-
/*
* Mark all held locks with a usage bit:
*/
static int
-mark_held_locks(struct task_struct *curr, enum mark_type mark)
+mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit)
{
- enum lock_usage_bit usage_bit;
struct held_lock *hlock;
int i;
for (i = 0; i < curr->lockdep_depth; i++) {
+ enum lock_usage_bit hlock_bit = base_bit;
hlock = curr->held_locks + i;
- usage_bit = 2 + (mark << 2); /* ENABLED */
if (hlock->read)
- usage_bit += 1; /* READ */
+ hlock_bit += LOCK_USAGE_READ_MASK;
- BUG_ON(usage_bit >= LOCK_USAGE_STATES);
+ BUG_ON(hlock_bit >= LOCK_USAGE_STATES);
if (!hlock->check)
continue;
- if (!mark_lock(curr, hlock, usage_bit))
+ if (!mark_lock(curr, hlock, hlock_bit))
return 0;
}
@@ -2823,7 +3378,7 @@
* We are going to turn hardirqs on, so set the
* usage bit for all held locks:
*/
- if (!mark_held_locks(curr, HARDIRQ))
+ if (!mark_held_locks(curr, LOCK_ENABLED_HARDIRQ))
return;
/*
* If we have softirqs enabled, then set the usage
@@ -2831,7 +3386,7 @@
* this bit from being set before)
*/
if (curr->softirqs_enabled)
- if (!mark_held_locks(curr, SOFTIRQ))
+ if (!mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ))
return;
curr->hardirq_enable_ip = ip;
@@ -2865,7 +3420,7 @@
/*
* See the fine text that goes along with this variable definition.
*/
- if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
+ if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled))
return;
/*
@@ -2879,6 +3434,7 @@
__trace_hardirqs_on_caller(ip);
current->lockdep_recursion = 0;
}
+NOKPROBE_SYMBOL(lockdep_hardirqs_on);
/*
* Hardirqs were disabled:
@@ -2908,6 +3464,7 @@
} else
debug_atomic_inc(redundant_hardirqs_off);
}
+NOKPROBE_SYMBOL(lockdep_hardirqs_off);
/*
* Softirqs will be enabled:
@@ -2945,7 +3502,7 @@
* enabled too:
*/
if (curr->hardirqs_enabled)
- mark_held_locks(curr, SOFTIRQ);
+ mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
current->lockdep_recursion = 0;
}
@@ -2981,8 +3538,12 @@
debug_atomic_inc(redundant_softirqs_off);
}
-static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
+static int
+mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
{
+ if (!check)
+ goto lock_used;
+
/*
* If non-trylock use in a hardirq or softirq context, then
* mark the lock as used in these contexts:
@@ -3026,6 +3587,11 @@
}
}
+lock_used:
+ /* mark it as used: */
+ if (!mark_lock(curr, hlock, LOCK_USED))
+ return 0;
+
return 1;
}
@@ -3057,35 +3623,6 @@
return 0;
}
-#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
-
-static inline
-int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
- enum lock_usage_bit new_bit)
-{
- WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
- return 1;
-}
-
-static inline int mark_irqflags(struct task_struct *curr,
- struct held_lock *hlock)
-{
- return 1;
-}
-
-static inline unsigned int task_irq_context(struct task_struct *task)
-{
- return 0;
-}
-
-static inline int separate_irq_context(struct task_struct *curr,
- struct held_lock *hlock)
-{
- return 0;
-}
-
-#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
-
/*
* Mark a lock with a usage bit, and validate the state transition:
*/
@@ -3094,6 +3631,11 @@
{
unsigned int new_mask = 1 << new_bit, ret = 1;
+ if (new_bit >= LOCK_USAGE_STATES) {
+ DEBUG_LOCKS_WARN_ON(1);
+ return 0;
+ }
+
/*
* If already set then do not dirty the cacheline,
* nor do any checks:
@@ -3113,29 +3655,17 @@
hlock_class(this)->usage_mask |= new_mask;
- if (!save_trace(hlock_class(this)->usage_traces + new_bit))
+ if (!(hlock_class(this)->usage_traces[new_bit] = save_trace()))
return 0;
switch (new_bit) {
-#define LOCKDEP_STATE(__STATE) \
- case LOCK_USED_IN_##__STATE: \
- case LOCK_USED_IN_##__STATE##_READ: \
- case LOCK_ENABLED_##__STATE: \
- case LOCK_ENABLED_##__STATE##_READ:
-#include "lockdep_states.h"
-#undef LOCKDEP_STATE
- ret = mark_lock_irq(curr, this, new_bit);
- if (!ret)
- return 0;
- break;
case LOCK_USED:
debug_atomic_dec(nr_unused_locks);
break;
default:
- if (!debug_locks_off_graph_unlock())
+ ret = mark_lock_irq(curr, this, new_bit);
+ if (!ret)
return 0;
- WARN_ON(1);
- return 0;
}
graph_unlock();
@@ -3153,10 +3683,31 @@
return ret;
}
+#else /* CONFIG_PROVE_LOCKING */
+
+static inline int
+mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
+{
+ return 1;
+}
+
+static inline unsigned int task_irq_context(struct task_struct *task)
+{
+ return 0;
+}
+
+static inline int separate_irq_context(struct task_struct *curr,
+ struct held_lock *hlock)
+{
+ return 0;
+}
+
+#endif /* CONFIG_PROVE_LOCKING */
+
/*
* Initialize a lock instance's lock-class mapping info:
*/
-static void __lockdep_init_map(struct lockdep_map *lock, const char *name,
+void lockdep_init_map(struct lockdep_map *lock, const char *name,
struct lock_class_key *key, int subclass)
{
int i;
@@ -3184,13 +3735,12 @@
if (DEBUG_LOCKS_WARN_ON(!key))
return;
/*
- * Sanity check, the lock-class key must be persistent:
+ * Sanity check, the lock-class key must either have been allocated
+ * statically or must have been registered as a dynamic key.
*/
- if (!static_obj(key)) {
- printk("BUG: key %px not in .data!\n", key);
- /*
- * What it says above ^^^^^, I suggest you read it.
- */
+ if (!static_obj(key) && !is_dynamic_key(key)) {
+ if (debug_locks)
+ printk(KERN_ERR "BUG: key %px has not been registered!\n", key);
DEBUG_LOCKS_WARN_ON(1);
return;
}
@@ -3212,26 +3762,20 @@
raw_local_irq_restore(flags);
}
}
-
-void lockdep_init_map(struct lockdep_map *lock, const char *name,
- struct lock_class_key *key, int subclass)
-{
- __lockdep_init_map(lock, name, key, subclass);
-}
EXPORT_SYMBOL_GPL(lockdep_init_map);
struct lock_class_key __lockdep_no_validate__;
EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
-static int
+static void
print_lock_nested_lock_not_held(struct task_struct *curr,
struct held_lock *hlock,
unsigned long ip)
{
if (!debug_locks_off())
- return 0;
+ return;
if (debug_locks_silent)
- return 0;
+ return;
pr_warn("\n");
pr_warn("==================================\n");
@@ -3253,8 +3797,6 @@
pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}
static int __lock_is_held(const struct lockdep_map *lock, int read);
@@ -3262,6 +3804,10 @@
/*
* This gets called for every mutex_lock*()/spin_lock*() operation.
* We maintain the dependency maps and validate the locking attempt:
+ *
+ * The callers must make sure that IRQs are disabled before calling it,
+ * otherwise we could get an interrupt which would want to take locks,
+ * which would end up in lockdep again.
*/
static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
int trylock, int read, int check, int hardirqs_off,
@@ -3279,14 +3825,6 @@
if (unlikely(!debug_locks))
return 0;
- /*
- * Lockdep should run with IRQs disabled, otherwise we could
- * get an interrupt which would want to take locks, which would
- * end up in lockdep and have you got a head-ache already?
- */
- if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
- return 0;
-
if (!prove_locking || lock->key == &__lockdep_no_validate__)
check = 0;
@@ -3300,7 +3838,9 @@
if (!class)
return 0;
}
- atomic_inc((atomic_t *)&class->ops);
+
+ debug_class_ops_inc(class);
+
if (very_verbose(class)) {
printk("\nacquire class [%px] %s", class->key, class->name);
if (class->name_version > 1)
@@ -3321,24 +3861,24 @@
if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
return 0;
- class_idx = class - lock_classes + 1;
+ class_idx = class - lock_classes;
if (depth) {
hlock = curr->held_locks + depth - 1;
if (hlock->class_idx == class_idx && nest_lock) {
- if (hlock->references) {
- /*
- * Check: unsigned int references:12, overflow.
- */
- if (DEBUG_LOCKS_WARN_ON(hlock->references == (1 << 12)-1))
- return 0;
+ if (!references)
+ references++;
+ if (!hlock->references)
hlock->references++;
- } else {
- hlock->references = 2;
- }
- return 1;
+ hlock->references += references;
+
+ /* Overflow */
+ if (DEBUG_LOCKS_WARN_ON(hlock->references < references))
+ return 0;
+
+ return 2;
}
}
@@ -3365,11 +3905,8 @@
#endif
hlock->pin_count = pin_count;
- if (check && !mark_irqflags(curr, hlock))
- return 0;
-
- /* mark it as used: */
- if (!mark_lock(curr, hlock, LOCK_USED))
+ /* Initialize the lock usage bit */
+ if (!mark_usage(curr, hlock, check))
return 0;
/*
@@ -3383,9 +3920,9 @@
* the hash, not class->key.
*/
/*
- * Whoops, we did it again.. ran straight out of our static allocation.
+ * Whoops, we did it again.. class_idx is invalid.
*/
- if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
+ if (DEBUG_LOCKS_WARN_ON(!test_bit(class_idx, lock_classes_in_use)))
return 0;
chain_key = curr->curr_chain_key;
@@ -3393,22 +3930,29 @@
/*
* How can we have a chain hash when we ain't got no keys?!
*/
- if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
+ if (DEBUG_LOCKS_WARN_ON(chain_key != INITIAL_CHAIN_KEY))
return 0;
chain_head = 1;
}
hlock->prev_chain_key = chain_key;
if (separate_irq_context(curr, hlock)) {
- chain_key = 0;
+ chain_key = INITIAL_CHAIN_KEY;
chain_head = 1;
}
chain_key = iterate_chain_key(chain_key, class_idx);
- if (nest_lock && !__lock_is_held(nest_lock, -1))
- return print_lock_nested_lock_not_held(curr, hlock, ip);
+ if (nest_lock && !__lock_is_held(nest_lock, -1)) {
+ print_lock_nested_lock_not_held(curr, hlock, ip);
+ return 0;
+ }
- if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
+ if (!debug_locks_silent) {
+ WARN_ON_ONCE(depth && !hlock_class(hlock - 1)->key);
+ WARN_ON_ONCE(!hlock_class(hlock)->key);
+ }
+
+ if (!validate_chain(curr, hlock, chain_head, chain_key))
return 0;
curr->curr_chain_key = chain_key;
@@ -3437,14 +3981,14 @@
return 1;
}
-static int
-print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
- unsigned long ip)
+static void print_unlock_imbalance_bug(struct task_struct *curr,
+ struct lockdep_map *lock,
+ unsigned long ip)
{
if (!debug_locks_off())
- return 0;
+ return;
if (debug_locks_silent)
- return 0;
+ return;
pr_warn("\n");
pr_warn("=====================================\n");
@@ -3462,8 +4006,6 @@
pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}
static int match_held_lock(const struct held_lock *hlock,
@@ -3495,7 +4037,7 @@
if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
return 0;
- if (hlock->class_idx == class - lock_classes + 1)
+ if (hlock->class_idx == class - lock_classes)
return 1;
}
@@ -3539,19 +4081,33 @@
}
static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
- int idx)
+ int idx, unsigned int *merged)
{
struct held_lock *hlock;
+ int first_idx = idx;
+
+ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+ return 0;
for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
- if (!__lock_acquire(hlock->instance,
+ switch (__lock_acquire(hlock->instance,
hlock_class(hlock)->subclass,
hlock->trylock,
hlock->read, hlock->check,
hlock->hardirqs_off,
hlock->nest_lock, hlock->acquire_ip,
- hlock->references, hlock->pin_count))
+ hlock->references, hlock->pin_count)) {
+ case 0:
return 1;
+ case 1:
+ break;
+ case 2:
+ *merged += (idx == first_idx);
+ break;
+ default:
+ WARN_ON(1);
+ return 0;
+ }
}
return 0;
}
@@ -3562,11 +4118,14 @@
unsigned long ip)
{
struct task_struct *curr = current;
+ unsigned int depth, merged = 0;
struct held_lock *hlock;
struct lock_class *class;
- unsigned int depth;
int i;
+ if (unlikely(!debug_locks))
+ return 0;
+
depth = curr->lockdep_depth;
/*
* This function is about (re)setting the class of a held lock,
@@ -3576,24 +4135,26 @@
return 0;
hlock = find_held_lock(curr, lock, depth, &i);
- if (!hlock)
- return print_unlock_imbalance_bug(curr, lock, ip);
+ if (!hlock) {
+ print_unlock_imbalance_bug(curr, lock, ip);
+ return 0;
+ }
lockdep_init_map(lock, name, key, 0);
class = register_lock_class(lock, subclass, 0);
- hlock->class_idx = class - lock_classes + 1;
+ hlock->class_idx = class - lock_classes;
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
- if (reacquire_held_locks(curr, depth, i))
+ if (reacquire_held_locks(curr, depth, i, &merged))
return 0;
/*
* I took it apart and put it back together again, except now I have
* these 'spare' parts.. where shall I put them.
*/
- if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
+ if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged))
return 0;
return 1;
}
@@ -3601,10 +4162,13 @@
static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
{
struct task_struct *curr = current;
+ unsigned int depth, merged = 0;
struct held_lock *hlock;
- unsigned int depth;
int i;
+ if (unlikely(!debug_locks))
+ return 0;
+
depth = curr->lockdep_depth;
/*
* This function is about (re)setting the class of a held lock,
@@ -3614,8 +4178,10 @@
return 0;
hlock = find_held_lock(curr, lock, depth, &i);
- if (!hlock)
- return print_unlock_imbalance_bug(curr, lock, ip);
+ if (!hlock) {
+ print_unlock_imbalance_bug(curr, lock, ip);
+ return 0;
+ }
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
@@ -3624,7 +4190,11 @@
hlock->read = 1;
hlock->acquire_ip = ip;
- if (reacquire_held_locks(curr, depth, i))
+ if (reacquire_held_locks(curr, depth, i, &merged))
+ return 0;
+
+ /* Merging can't happen with unchanged classes.. */
+ if (DEBUG_LOCKS_WARN_ON(merged))
return 0;
/*
@@ -3633,6 +4203,7 @@
*/
if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
return 0;
+
return 1;
}
@@ -3644,11 +4215,11 @@
* @nested is an hysterical artifact, needs a tree wide cleanup.
*/
static int
-__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
+__lock_release(struct lockdep_map *lock, unsigned long ip)
{
struct task_struct *curr = current;
+ unsigned int depth, merged = 1;
struct held_lock *hlock;
- unsigned int depth;
int i;
if (unlikely(!debug_locks))
@@ -3659,16 +4230,20 @@
* So we're all set to release this lock.. wait what lock? We don't
* own any locks, you've been drinking again?
*/
- if (DEBUG_LOCKS_WARN_ON(depth <= 0))
- return print_unlock_imbalance_bug(curr, lock, ip);
+ if (depth <= 0) {
+ print_unlock_imbalance_bug(curr, lock, ip);
+ return 0;
+ }
/*
* Check whether the lock exists in the current stack
* of held locks:
*/
hlock = find_held_lock(curr, lock, depth, &i);
- if (!hlock)
- return print_unlock_imbalance_bug(curr, lock, ip);
+ if (!hlock) {
+ print_unlock_imbalance_bug(curr, lock, ip);
+ return 0;
+ }
if (hlock->instance == lock)
lock_release_holdtime(hlock);
@@ -3696,20 +4271,33 @@
curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
- if (reacquire_held_locks(curr, depth, i + 1))
+ /*
+ * The most likely case is when the unlock is on the innermost
+ * lock. In this case, we are done!
+ */
+ if (i == depth-1)
+ return 1;
+
+ if (reacquire_held_locks(curr, depth, i + 1, &merged))
return 0;
/*
* We had N bottles of beer on the wall, we drank one, but now
* there's not N-1 bottles of beer left on the wall...
+ * Pouring two of the bottles together is acceptable.
*/
- if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
- return 0;
+ DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged);
- return 1;
+ /*
+ * Since reacquire_held_locks() would have called check_chain_key()
+ * indirectly via __lock_acquire(), we don't need to do it again
+ * on return.
+ */
+ return 0;
}
-static int __lock_is_held(const struct lockdep_map *lock, int read)
+static nokprobe_inline
+int __lock_is_held(const struct lockdep_map *lock, int read)
{
struct task_struct *curr = current;
int i;
@@ -3808,8 +4396,7 @@
*/
static void check_flags(unsigned long flags)
{
-#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
- defined(CONFIG_TRACE_IRQFLAGS)
+#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP)
if (!debug_locks)
return;
@@ -3916,7 +4503,7 @@
check_flags(flags);
current->lockdep_recursion = 1;
trace_lock_release(lock, ip);
- if (__lock_release(lock, nested, ip))
+ if (__lock_release(lock, ip))
check_chain_key(current);
current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
@@ -3942,6 +4529,7 @@
return ret;
}
EXPORT_SYMBOL_GPL(lock_is_held_type);
+NOKPROBE_SYMBOL(lock_is_held_type);
struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
{
@@ -3998,14 +4586,14 @@
EXPORT_SYMBOL_GPL(lock_unpin_lock);
#ifdef CONFIG_LOCK_STAT
-static int
-print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
- unsigned long ip)
+static void print_lock_contention_bug(struct task_struct *curr,
+ struct lockdep_map *lock,
+ unsigned long ip)
{
if (!debug_locks_off())
- return 0;
+ return;
if (debug_locks_silent)
- return 0;
+ return;
pr_warn("\n");
pr_warn("=================================\n");
@@ -4023,8 +4611,6 @@
pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}
static void
@@ -4169,9 +4755,7 @@
int i;
raw_local_irq_save(flags);
- current->curr_chain_key = 0;
- current->lockdep_depth = 0;
- current->lockdep_recursion = 0;
+ lockdep_init_task(current);
memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
nr_hardirq_chains = 0;
nr_softirq_chains = 0;
@@ -4182,26 +4766,132 @@
raw_local_irq_restore(flags);
}
-static void zap_class(struct lock_class *class)
+/* Remove a class from a lock chain. Must be called with the graph lock held. */
+static void remove_class_from_lock_chain(struct pending_free *pf,
+ struct lock_chain *chain,
+ struct lock_class *class)
{
+#ifdef CONFIG_PROVE_LOCKING
+ struct lock_chain *new_chain;
+ u64 chain_key;
int i;
+ for (i = chain->base; i < chain->base + chain->depth; i++) {
+ if (chain_hlocks[i] != class - lock_classes)
+ continue;
+ /* The code below leaks one chain_hlock[] entry. */
+ if (--chain->depth > 0) {
+ memmove(&chain_hlocks[i], &chain_hlocks[i + 1],
+ (chain->base + chain->depth - i) *
+ sizeof(chain_hlocks[0]));
+ }
+ /*
+ * Each lock class occurs at most once in a lock chain so once
+ * we found a match we can break out of this loop.
+ */
+ goto recalc;
+ }
+ /* Since the chain has not been modified, return. */
+ return;
+
+recalc:
+ chain_key = INITIAL_CHAIN_KEY;
+ for (i = chain->base; i < chain->base + chain->depth; i++)
+ chain_key = iterate_chain_key(chain_key, chain_hlocks[i]);
+ if (chain->depth && chain->chain_key == chain_key)
+ return;
+ /* Overwrite the chain key for concurrent RCU readers. */
+ WRITE_ONCE(chain->chain_key, chain_key);
+ /*
+ * Note: calling hlist_del_rcu() from inside a
+ * hlist_for_each_entry_rcu() loop is safe.
+ */
+ hlist_del_rcu(&chain->entry);
+ __set_bit(chain - lock_chains, pf->lock_chains_being_freed);
+ if (chain->depth == 0)
+ return;
+ /*
+ * If the modified lock chain matches an existing lock chain, drop
+ * the modified lock chain.
+ */
+ if (lookup_chain_cache(chain_key))
+ return;
+ new_chain = alloc_lock_chain();
+ if (WARN_ON_ONCE(!new_chain)) {
+ debug_locks_off();
+ return;
+ }
+ *new_chain = *chain;
+ hlist_add_head_rcu(&new_chain->entry, chainhashentry(chain_key));
+#endif
+}
+
+/* Must be called with the graph lock held. */
+static void remove_class_from_lock_chains(struct pending_free *pf,
+ struct lock_class *class)
+{
+ struct lock_chain *chain;
+ struct hlist_head *head;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) {
+ head = chainhash_table + i;
+ hlist_for_each_entry_rcu(chain, head, entry) {
+ remove_class_from_lock_chain(pf, chain, class);
+ }
+ }
+}
+
+/*
+ * Remove all references to a lock class. The caller must hold the graph lock.
+ */
+static void zap_class(struct pending_free *pf, struct lock_class *class)
+{
+ struct lock_list *entry;
+ int i;
+
+ WARN_ON_ONCE(!class->key);
+
/*
* Remove all dependencies this lock is
* involved in:
*/
- for (i = 0; i < nr_list_entries; i++) {
- if (list_entries[i].class == class)
- list_del_rcu(&list_entries[i].entry);
+ for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) {
+ entry = list_entries + i;
+ if (entry->class != class && entry->links_to != class)
+ continue;
+ __clear_bit(i, list_entries_in_use);
+ nr_list_entries--;
+ list_del_rcu(&entry->entry);
}
- /*
- * Unhash the class and remove it from the all_lock_classes list:
- */
- hlist_del_rcu(&class->hash_entry);
- list_del_rcu(&class->lock_entry);
+ if (list_empty(&class->locks_after) &&
+ list_empty(&class->locks_before)) {
+ list_move_tail(&class->lock_entry, &pf->zapped);
+ hlist_del_rcu(&class->hash_entry);
+ WRITE_ONCE(class->key, NULL);
+ WRITE_ONCE(class->name, NULL);
+ nr_lock_classes--;
+ __clear_bit(class - lock_classes, lock_classes_in_use);
+ } else {
+ WARN_ONCE(true, "%s() failed for class %s\n", __func__,
+ class->name);
+ }
- RCU_INIT_POINTER(class->key, NULL);
- RCU_INIT_POINTER(class->name, NULL);
+ remove_class_from_lock_chains(pf, class);
+}
+
+static void reinit_class(struct lock_class *class)
+{
+ void *const p = class;
+ const unsigned int offset = offsetof(struct lock_class, key);
+
+ WARN_ON_ONCE(!class->lock_entry.next);
+ WARN_ON_ONCE(!list_empty(&class->locks_after));
+ WARN_ON_ONCE(!list_empty(&class->locks_before));
+ memset(p + offset, 0, sizeof(*class) - offset);
+ WARN_ON_ONCE(!class->lock_entry.next);
+ WARN_ON_ONCE(!list_empty(&class->locks_after));
+ WARN_ON_ONCE(!list_empty(&class->locks_before));
}
static inline int within(const void *addr, void *start, unsigned long size)
@@ -4209,66 +4899,201 @@
return addr >= start && addr < start + size;
}
+static bool inside_selftest(void)
+{
+ return current == lockdep_selftest_task_struct;
+}
+
+/* The caller must hold the graph lock. */
+static struct pending_free *get_pending_free(void)
+{
+ return delayed_free.pf + delayed_free.index;
+}
+
+static void free_zapped_rcu(struct rcu_head *cb);
+
+/*
+ * Schedule an RCU callback if no RCU callback is pending. Must be called with
+ * the graph lock held.
+ */
+static void call_rcu_zapped(struct pending_free *pf)
+{
+ WARN_ON_ONCE(inside_selftest());
+
+ if (list_empty(&pf->zapped))
+ return;
+
+ if (delayed_free.scheduled)
+ return;
+
+ delayed_free.scheduled = true;
+
+ WARN_ON_ONCE(delayed_free.pf + delayed_free.index != pf);
+ delayed_free.index ^= 1;
+
+ call_rcu(&delayed_free.rcu_head, free_zapped_rcu);
+}
+
+/* The caller must hold the graph lock. May be called from RCU context. */
+static void __free_zapped_classes(struct pending_free *pf)
+{
+ struct lock_class *class;
+
+ check_data_structures();
+
+ list_for_each_entry(class, &pf->zapped, lock_entry)
+ reinit_class(class);
+
+ list_splice_init(&pf->zapped, &free_lock_classes);
+
+#ifdef CONFIG_PROVE_LOCKING
+ bitmap_andnot(lock_chains_in_use, lock_chains_in_use,
+ pf->lock_chains_being_freed, ARRAY_SIZE(lock_chains));
+ bitmap_clear(pf->lock_chains_being_freed, 0, ARRAY_SIZE(lock_chains));
+#endif
+}
+
+static void free_zapped_rcu(struct rcu_head *ch)
+{
+ struct pending_free *pf;
+ unsigned long flags;
+
+ if (WARN_ON_ONCE(ch != &delayed_free.rcu_head))
+ return;
+
+ raw_local_irq_save(flags);
+ arch_spin_lock(&lockdep_lock);
+ current->lockdep_recursion = 1;
+
+ /* closed head */
+ pf = delayed_free.pf + (delayed_free.index ^ 1);
+ __free_zapped_classes(pf);
+ delayed_free.scheduled = false;
+
+ /*
+ * If there's anything on the open list, close and start a new callback.
+ */
+ call_rcu_zapped(delayed_free.pf + delayed_free.index);
+
+ current->lockdep_recursion = 0;
+ arch_spin_unlock(&lockdep_lock);
+ raw_local_irq_restore(flags);
+}
+
+/*
+ * Remove all lock classes from the class hash table and from the
+ * all_lock_classes list whose key or name is in the address range [start,
+ * start + size). Move these lock classes to the zapped_classes list. Must
+ * be called with the graph lock held.
+ */
+static void __lockdep_free_key_range(struct pending_free *pf, void *start,
+ unsigned long size)
+{
+ struct lock_class *class;
+ struct hlist_head *head;
+ int i;
+
+ /* Unhash all classes that were created by a module. */
+ for (i = 0; i < CLASSHASH_SIZE; i++) {
+ head = classhash_table + i;
+ hlist_for_each_entry_rcu(class, head, hash_entry) {
+ if (!within(class->key, start, size) &&
+ !within(class->name, start, size))
+ continue;
+ zap_class(pf, class);
+ }
+ }
+}
+
/*
* Used in module.c to remove lock classes from memory that is going to be
* freed; and possibly re-used by other modules.
*
- * We will have had one sync_sched() before getting here, so we're guaranteed
- * nobody will look up these exact classes -- they're properly dead but still
- * allocated.
+ * We will have had one synchronize_rcu() before getting here, so we're
+ * guaranteed nobody will look up these exact classes -- they're properly dead
+ * but still allocated.
*/
-void lockdep_free_key_range(void *start, unsigned long size)
+static void lockdep_free_key_range_reg(void *start, unsigned long size)
{
- struct lock_class *class;
- struct hlist_head *head;
+ struct pending_free *pf;
unsigned long flags;
- int i;
- int locked;
+
+ init_data_structures_once();
raw_local_irq_save(flags);
- locked = graph_lock();
-
- /*
- * Unhash all classes that were created by this module:
- */
- for (i = 0; i < CLASSHASH_SIZE; i++) {
- head = classhash_table + i;
- hlist_for_each_entry_rcu(class, head, hash_entry) {
- if (within(class->key, start, size))
- zap_class(class);
- else if (within(class->name, start, size))
- zap_class(class);
- }
- }
-
- if (locked)
- graph_unlock();
+ arch_spin_lock(&lockdep_lock);
+ current->lockdep_recursion = 1;
+ pf = get_pending_free();
+ __lockdep_free_key_range(pf, start, size);
+ call_rcu_zapped(pf);
+ current->lockdep_recursion = 0;
+ arch_spin_unlock(&lockdep_lock);
raw_local_irq_restore(flags);
/*
* Wait for any possible iterators from look_up_lock_class() to pass
* before continuing to free the memory they refer to.
- *
- * sync_sched() is sufficient because the read-side is IRQ disable.
*/
- synchronize_sched();
-
- /*
- * XXX at this point we could return the resources to the pool;
- * instead we leak them. We would need to change to bitmap allocators
- * instead of the linear allocators we have now.
- */
+ synchronize_rcu();
}
-void lockdep_reset_lock(struct lockdep_map *lock)
+/*
+ * Free all lockdep keys in the range [start, start+size). Does not sleep.
+ * Ignores debug_locks. Must only be used by the lockdep selftests.
+ */
+static void lockdep_free_key_range_imm(void *start, unsigned long size)
+{
+ struct pending_free *pf = delayed_free.pf;
+ unsigned long flags;
+
+ init_data_structures_once();
+
+ raw_local_irq_save(flags);
+ arch_spin_lock(&lockdep_lock);
+ __lockdep_free_key_range(pf, start, size);
+ __free_zapped_classes(pf);
+ arch_spin_unlock(&lockdep_lock);
+ raw_local_irq_restore(flags);
+}
+
+void lockdep_free_key_range(void *start, unsigned long size)
+{
+ init_data_structures_once();
+
+ if (inside_selftest())
+ lockdep_free_key_range_imm(start, size);
+ else
+ lockdep_free_key_range_reg(start, size);
+}
+
+/*
+ * Check whether any element of the @lock->class_cache[] array refers to a
+ * registered lock class. The caller must hold either the graph lock or the
+ * RCU read lock.
+ */
+static bool lock_class_cache_is_registered(struct lockdep_map *lock)
{
struct lock_class *class;
struct hlist_head *head;
- unsigned long flags;
int i, j;
- int locked;
- raw_local_irq_save(flags);
+ for (i = 0; i < CLASSHASH_SIZE; i++) {
+ head = classhash_table + i;
+ hlist_for_each_entry_rcu(class, head, hash_entry) {
+ for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
+ if (lock->class_cache[j] == class)
+ return true;
+ }
+ }
+ return false;
+}
+
+/* The caller must hold the graph lock. Does not sleep. */
+static void __lockdep_reset_lock(struct pending_free *pf,
+ struct lockdep_map *lock)
+{
+ struct lock_class *class;
+ int j;
/*
* Remove all classes this lock might have:
@@ -4279,39 +5104,105 @@
*/
class = look_up_lock_class(lock, j);
if (class)
- zap_class(class);
+ zap_class(pf, class);
}
/*
* Debug check: in the end all mapped classes should
* be gone.
*/
+ if (WARN_ON_ONCE(lock_class_cache_is_registered(lock)))
+ debug_locks_off();
+}
+
+/*
+ * Remove all information lockdep has about a lock if debug_locks == 1. Free
+ * released data structures from RCU context.
+ */
+static void lockdep_reset_lock_reg(struct lockdep_map *lock)
+{
+ struct pending_free *pf;
+ unsigned long flags;
+ int locked;
+
+ raw_local_irq_save(flags);
locked = graph_lock();
- for (i = 0; i < CLASSHASH_SIZE; i++) {
- head = classhash_table + i;
- hlist_for_each_entry_rcu(class, head, hash_entry) {
- int match = 0;
+ if (!locked)
+ goto out_irq;
- for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
- match |= class == lock->class_cache[j];
+ pf = get_pending_free();
+ __lockdep_reset_lock(pf, lock);
+ call_rcu_zapped(pf);
- if (unlikely(match)) {
- if (debug_locks_off_graph_unlock()) {
- /*
- * We all just reset everything, how did it match?
- */
- WARN_ON(1);
- }
- goto out_restore;
- }
- }
- }
- if (locked)
- graph_unlock();
-
-out_restore:
+ graph_unlock();
+out_irq:
raw_local_irq_restore(flags);
}
+/*
+ * Reset a lock. Does not sleep. Ignores debug_locks. Must only be used by the
+ * lockdep selftests.
+ */
+static void lockdep_reset_lock_imm(struct lockdep_map *lock)
+{
+ struct pending_free *pf = delayed_free.pf;
+ unsigned long flags;
+
+ raw_local_irq_save(flags);
+ arch_spin_lock(&lockdep_lock);
+ __lockdep_reset_lock(pf, lock);
+ __free_zapped_classes(pf);
+ arch_spin_unlock(&lockdep_lock);
+ raw_local_irq_restore(flags);
+}
+
+void lockdep_reset_lock(struct lockdep_map *lock)
+{
+ init_data_structures_once();
+
+ if (inside_selftest())
+ lockdep_reset_lock_imm(lock);
+ else
+ lockdep_reset_lock_reg(lock);
+}
+
+/* Unregister a dynamically allocated key. */
+void lockdep_unregister_key(struct lock_class_key *key)
+{
+ struct hlist_head *hash_head = keyhashentry(key);
+ struct lock_class_key *k;
+ struct pending_free *pf;
+ unsigned long flags;
+ bool found = false;
+
+ might_sleep();
+
+ if (WARN_ON_ONCE(static_obj(key)))
+ return;
+
+ raw_local_irq_save(flags);
+ if (!graph_lock())
+ goto out_irq;
+
+ pf = get_pending_free();
+ hlist_for_each_entry_rcu(k, hash_head, hash_entry) {
+ if (k == key) {
+ hlist_del_rcu(&k->hash_entry);
+ found = true;
+ break;
+ }
+ }
+ WARN_ON_ONCE(!found);
+ __lockdep_free_key_range(pf, key, 1);
+ call_rcu_zapped(pf);
+ graph_unlock();
+out_irq:
+ raw_local_irq_restore(flags);
+
+ /* Wait until is_dynamic_key() has finished accessing k->hash_entry. */
+ synchronize_rcu();
+}
+EXPORT_SYMBOL_GPL(lockdep_unregister_key);
+
void __init lockdep_init(void)
{
printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
@@ -4324,20 +5215,31 @@
printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
- printk(" memory used by lock dependency info: %lu kB\n",
- (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
- sizeof(struct list_head) * CLASSHASH_SIZE +
- sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
- sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
- sizeof(struct list_head) * CHAINHASH_SIZE
+ printk(" memory used by lock dependency info: %zu kB\n",
+ (sizeof(lock_classes) +
+ sizeof(lock_classes_in_use) +
+ sizeof(classhash_table) +
+ sizeof(list_entries) +
+ sizeof(list_entries_in_use) +
+ sizeof(chainhash_table) +
+ sizeof(delayed_free)
#ifdef CONFIG_PROVE_LOCKING
- + sizeof(struct circular_queue)
+ + sizeof(lock_cq)
+ + sizeof(lock_chains)
+ + sizeof(lock_chains_in_use)
+ + sizeof(chain_hlocks)
#endif
) / 1024
);
- printk(" per task-struct memory footprint: %lu bytes\n",
- sizeof(struct held_lock) * MAX_LOCK_DEPTH);
+#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
+ printk(" memory used for stack traces: %zu kB\n",
+ (sizeof(stack_trace) + sizeof(stack_trace_hash)) / 1024
+ );
+#endif
+
+ printk(" per task-struct memory footprint: %zu bytes\n",
+ sizeof(((struct task_struct *)NULL)->held_locks));
}
static void