Update Linux to v5.4.148
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz
Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 233459c..3ec8fd2 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -482,7 +482,7 @@
struct lock_trace *trace, *t2;
struct hlist_head *hash_head;
u32 hash;
- unsigned int max_entries;
+ int max_entries;
BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE);
BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES);
@@ -490,10 +490,8 @@
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);
- if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES -
- LOCK_TRACE_SIZE_IN_LONGS - 1) {
+ if (max_entries <= 0) {
if (!debug_locks_off_graph_unlock())
return NULL;
@@ -502,6 +500,7 @@
return NULL;
}
+ trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
hash = jhash(trace->entries, trace->nr_entries *
sizeof(trace->entries[0]), 0);
@@ -876,7 +875,8 @@
/* Debug-check: all keys must be persistent! */
debug_locks_off();
pr_err("INFO: trying to register non-static key.\n");
- pr_err("the code is fine but needs lockdep annotation.\n");
+ pr_err("The code is fine but needs lockdep annotation, or maybe\n");
+ pr_err("you didn't initialize this object before use?\n");
pr_err("turning off the locking correctness validator.\n");
dump_stack();
return false;
@@ -1720,9 +1720,11 @@
this.class = class;
raw_local_irq_save(flags);
+ current->lockdep_recursion = 1;
arch_spin_lock(&lockdep_lock);
ret = __lockdep_count_forward_deps(&this);
arch_spin_unlock(&lockdep_lock);
+ current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
return ret;
@@ -1747,9 +1749,11 @@
this.class = class;
raw_local_irq_save(flags);
+ current->lockdep_recursion = 1;
arch_spin_lock(&lockdep_lock);
ret = __lockdep_count_backward_deps(&this);
arch_spin_unlock(&lockdep_lock);
+ current->lockdep_recursion = 0;
raw_local_irq_restore(flags);
return ret;
@@ -1937,7 +1941,56 @@
}
/*
- * printk the shortest lock dependencies from @start to @end in reverse order:
+ * Dependency path printing:
+ *
+ * After BFS we get a lock dependency path (linked via ->parent of lock_list),
+ * printing out each lock in the dependency path will help on understanding how
+ * the deadlock could happen. Here are some details about dependency path
+ * printing:
+ *
+ * 1) A lock_list can be either forwards or backwards for a lock dependency,
+ * for a lock dependency A -> B, there are two lock_lists:
+ *
+ * a) lock_list in the ->locks_after list of A, whose ->class is B and
+ * ->links_to is A. In this case, we can say the lock_list is
+ * "A -> B" (forwards case).
+ *
+ * b) lock_list in the ->locks_before list of B, whose ->class is A
+ * and ->links_to is B. In this case, we can say the lock_list is
+ * "B <- A" (bacwards case).
+ *
+ * The ->trace of both a) and b) point to the call trace where B was
+ * acquired with A held.
+ *
+ * 2) A "helper" lock_list is introduced during BFS, this lock_list doesn't
+ * represent a certain lock dependency, it only provides an initial entry
+ * for BFS. For example, BFS may introduce a "helper" lock_list whose
+ * ->class is A, as a result BFS will search all dependencies starting with
+ * A, e.g. A -> B or A -> C.
+ *
+ * The notation of a forwards helper lock_list is like "-> A", which means
+ * we should search the forwards dependencies starting with "A", e.g A -> B
+ * or A -> C.
+ *
+ * The notation of a bacwards helper lock_list is like "<- B", which means
+ * we should search the backwards dependencies ending with "B", e.g.
+ * B <- A or B <- C.
+ */
+
+/*
+ * printk the shortest lock dependencies from @root to @leaf in reverse order.
+ *
+ * We have a lock dependency path as follow:
+ *
+ * @root @leaf
+ * | |
+ * V V
+ * ->parent ->parent
+ * | lock_list | <--------- | lock_list | ... | lock_list | <--------- | lock_list |
+ * | -> L1 | | L1 -> L2 | ... |Ln-2 -> Ln-1| | Ln-1 -> Ln|
+ *
+ * , so it's natural that we start from @leaf and print every ->class and
+ * ->trace until we reach the @root.
*/
static void __used
print_shortest_lock_dependencies(struct lock_list *leaf,
@@ -1965,6 +2018,61 @@
} while (entry && (depth >= 0));
}
+/*
+ * printk the shortest lock dependencies from @leaf to @root.
+ *
+ * We have a lock dependency path (from a backwards search) as follow:
+ *
+ * @leaf @root
+ * | |
+ * V V
+ * ->parent ->parent
+ * | lock_list | ---------> | lock_list | ... | lock_list | ---------> | lock_list |
+ * | L2 <- L1 | | L3 <- L2 | ... | Ln <- Ln-1 | | <- Ln |
+ *
+ * , so when we iterate from @leaf to @root, we actually print the lock
+ * dependency path L1 -> L2 -> .. -> Ln in the non-reverse order.
+ *
+ * Another thing to notice here is that ->class of L2 <- L1 is L1, while the
+ * ->trace of L2 <- L1 is the call trace of L2, in fact we don't have the call
+ * trace of L1 in the dependency path, which is alright, because most of the
+ * time we can figure out where L1 is held from the call trace of L2.
+ */
+static void __used
+print_shortest_lock_dependencies_backwards(struct lock_list *leaf,
+ struct lock_list *root)
+{
+ struct lock_list *entry = leaf;
+ const struct lock_trace *trace = NULL;
+ int depth;
+
+ /*compute depth from generated tree by BFS*/
+ depth = get_lock_depth(leaf);
+
+ do {
+ print_lock_class_header(entry->class, depth);
+ if (trace) {
+ printk("%*s ... acquired at:\n", depth, "");
+ print_lock_trace(trace, 2);
+ printk("\n");
+ }
+
+ /*
+ * Record the pointer to the trace for the next lock_list
+ * entry, see the comments for the function.
+ */
+ trace = entry->trace;
+
+ if (depth == 0 && (entry != root)) {
+ printk("lockdep:%s bad path found in chain graph\n", __func__);
+ break;
+ }
+
+ entry = get_lock_parent(entry);
+ depth--;
+ } while (entry && (depth >= 0));
+}
+
static void
print_irq_lock_scenario(struct lock_list *safe_entry,
struct lock_list *unsafe_entry,
@@ -2082,7 +2190,7 @@
prev_root->trace = save_trace();
if (!prev_root->trace)
return;
- print_shortest_lock_dependencies(backwards_entry, prev_root);
+ print_shortest_lock_dependencies_backwards(backwards_entry, prev_root);
pr_warn("\nthe dependencies between the lock to be acquired");
pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
@@ -2269,8 +2377,18 @@
* 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.
+ *
+ * Note, we should only keep the LOCKF_ENABLED_IRQ_ALL bits, considering
+ * the follow case:
+ *
+ * When trying to add A -> B to the graph, we find that there is a
+ * hardirq-safe L, that L -> ... -> A, and another hardirq-unsafe M,
+ * that B -> ... -> M. However M is **softirq-safe**, if we use exact
+ * invert bits of M's usage_mask, we will find another lock N that is
+ * **softirq-unsafe** and N -> ... -> A, however N -> .. -> M will not
+ * cause a inversion deadlock.
*/
- backward_mask = original_mask(target_entry1->class->usage_mask);
+ backward_mask = original_mask(target_entry1->class->usage_mask & LOCKF_ENABLED_IRQ_ALL);
ret = find_usage_backwards(&this, backward_mask, &target_entry);
if (ret < 0) {
@@ -2299,18 +2417,6 @@
return 0;
}
-static void inc_chains(void)
-{
- if (current->hardirq_context)
- nr_hardirq_chains++;
- else {
- if (current->softirq_context)
- nr_softirq_chains++;
- else
- nr_process_chains++;
- }
-}
-
#else
static inline int check_irq_usage(struct task_struct *curr,
@@ -2318,13 +2424,27 @@
{
return 1;
}
+#endif /* CONFIG_TRACE_IRQFLAGS */
-static inline void inc_chains(void)
+static void inc_chains(int irq_context)
{
- nr_process_chains++;
+ if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
+ nr_hardirq_chains++;
+ else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
+ nr_softirq_chains++;
+ else
+ nr_process_chains++;
}
-#endif /* CONFIG_TRACE_IRQFLAGS */
+static void dec_chains(int irq_context)
+{
+ if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
+ nr_hardirq_chains--;
+ else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
+ nr_softirq_chains--;
+ else
+ nr_process_chains--;
+}
static void
print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
@@ -2844,7 +2964,7 @@
hlist_add_head_rcu(&chain->entry, hash_head);
debug_atomic_inc(chain_lookup_misses);
- inc_chains();
+ inc_chains(chain->irq_context);
return 1;
}
@@ -3597,7 +3717,8 @@
static inline unsigned int task_irq_context(struct task_struct *task)
{
- return 2 * !!task->hardirq_context + !!task->softirq_context;
+ return LOCK_CHAIN_HARDIRQ_CONTEXT * !!task->hardirq_context +
+ LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context;
}
static int separate_irq_context(struct task_struct *curr,
@@ -4802,6 +4923,8 @@
return;
/* Overwrite the chain key for concurrent RCU readers. */
WRITE_ONCE(chain->chain_key, chain_key);
+ dec_chains(chain->irq_context);
+
/*
* Note: calling hlist_del_rcu() from inside a
* hlist_for_each_entry_rcu() loop is safe.
@@ -4823,6 +4946,7 @@
}
*new_chain = *chain;
hlist_add_head_rcu(&new_chain->entry, chainhashentry(chain_key));
+ inc_chains(new_chain->irq_context);
#endif
}