Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 39cb23d..1861103 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -1,26 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0+
/*
* Read-Copy Update mechanism for mutual exclusion
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
* Copyright IBM Corporation, 2001
*
* Authors: Dipankar Sarma <dipankar@in.ibm.com>
* Manfred Spraul <manfred@colorfullife.com>
*
- * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
+ * Based on the original work by Paul McKenney <paulmck@linux.ibm.com>
* and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
* Papers:
* http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
@@ -52,6 +39,7 @@
#include <linux/tick.h>
#include <linux/rcupdate_wait.h>
#include <linux/sched/isolation.h>
+#include <linux/kprobes.h>
#define CREATE_TRACE_POINTS
@@ -73,9 +61,15 @@
#ifdef CONFIG_DEBUG_LOCK_ALLOC
/**
- * rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section?
+ * rcu_read_lock_held_common() - might we be in RCU-sched read-side critical section?
+ * @ret: Best guess answer if lockdep cannot be relied on
*
- * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an
+ * Returns true if lockdep must be ignored, in which case *ret contains
+ * the best guess described below. Otherwise returns false, in which
+ * case *ret tells the caller nothing and the caller should instead
+ * consult lockdep.
+ *
+ * If CONFIG_DEBUG_LOCK_ALLOC is selected, set *ret to nonzero iff in an
* RCU-sched read-side critical section. In absence of
* CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side
* critical section unless it can prove otherwise. Note that disabling
@@ -87,35 +81,45 @@
* Check debug_lockdep_rcu_enabled() to prevent false positives during boot
* and while lockdep is disabled.
*
- * Note that if the CPU is in the idle loop from an RCU point of
- * view (ie: that we are in the section between rcu_idle_enter() and
- * rcu_idle_exit()) then rcu_read_lock_held() returns false even if the CPU
- * did an rcu_read_lock(). The reason for this is that RCU ignores CPUs
- * that are in such a section, considering these as in extended quiescent
- * state, so such a CPU is effectively never in an RCU read-side critical
- * section regardless of what RCU primitives it invokes. This state of
- * affairs is required --- we need to keep an RCU-free window in idle
- * where the CPU may possibly enter into low power mode. This way we can
- * notice an extended quiescent state to other CPUs that started a grace
- * period. Otherwise we would delay any grace period as long as we run in
- * the idle task.
+ * Note that if the CPU is in the idle loop from an RCU point of view (ie:
+ * that we are in the section between rcu_idle_enter() and rcu_idle_exit())
+ * then rcu_read_lock_held() sets *ret to false even if the CPU did an
+ * rcu_read_lock(). The reason for this is that RCU ignores CPUs that are
+ * in such a section, considering these as in extended quiescent state,
+ * so such a CPU is effectively never in an RCU read-side critical section
+ * regardless of what RCU primitives it invokes. This state of affairs is
+ * required --- we need to keep an RCU-free window in idle where the CPU may
+ * possibly enter into low power mode. This way we can notice an extended
+ * quiescent state to other CPUs that started a grace period. Otherwise
+ * we would delay any grace period as long as we run in the idle task.
*
- * Similarly, we avoid claiming an SRCU read lock held if the current
+ * Similarly, we avoid claiming an RCU read lock held if the current
* CPU is offline.
*/
+static bool rcu_read_lock_held_common(bool *ret)
+{
+ if (!debug_lockdep_rcu_enabled()) {
+ *ret = 1;
+ return true;
+ }
+ if (!rcu_is_watching()) {
+ *ret = 0;
+ return true;
+ }
+ if (!rcu_lockdep_current_cpu_online()) {
+ *ret = 0;
+ return true;
+ }
+ return false;
+}
+
int rcu_read_lock_sched_held(void)
{
- int lockdep_opinion = 0;
+ bool ret;
- if (!debug_lockdep_rcu_enabled())
- return 1;
- if (!rcu_is_watching())
- return 0;
- if (!rcu_lockdep_current_cpu_online())
- return 0;
- if (debug_locks)
- lockdep_opinion = lock_is_held(&rcu_sched_lock_map);
- return lockdep_opinion || !preemptible();
+ if (rcu_read_lock_held_common(&ret))
+ return ret;
+ return lock_is_held(&rcu_sched_lock_map) || !preemptible();
}
EXPORT_SYMBOL(rcu_read_lock_sched_held);
#endif
@@ -148,8 +152,7 @@
*/
bool rcu_gp_is_expedited(void)
{
- return rcu_expedited || atomic_read(&rcu_expedited_nesting) ||
- rcu_scheduler_active == RCU_SCHEDULER_INIT;
+ return rcu_expedited || atomic_read(&rcu_expedited_nesting);
}
EXPORT_SYMBOL_GPL(rcu_gp_is_expedited);
@@ -203,11 +206,7 @@
if (!IS_ENABLED(CONFIG_PROVE_RCU))
return;
synchronize_rcu();
- synchronize_rcu_bh();
- synchronize_sched();
synchronize_rcu_expedited();
- synchronize_rcu_bh_expedited();
- synchronize_sched_expedited();
}
#if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU)
@@ -253,6 +252,7 @@
current->lockdep_recursion == 0;
}
EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
+NOKPROBE_SYMBOL(debug_lockdep_rcu_enabled);
/**
* rcu_read_lock_held() - might we be in RCU read-side critical section?
@@ -276,12 +276,10 @@
*/
int rcu_read_lock_held(void)
{
- if (!debug_lockdep_rcu_enabled())
- return 1;
- if (!rcu_is_watching())
- return 0;
- if (!rcu_lockdep_current_cpu_online())
- return 0;
+ bool ret;
+
+ if (rcu_read_lock_held_common(&ret))
+ return ret;
return lock_is_held(&rcu_lock_map);
}
EXPORT_SYMBOL_GPL(rcu_read_lock_held);
@@ -298,21 +296,33 @@
*
* Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
*
- * Note that rcu_read_lock() is disallowed if the CPU is either idle or
+ * Note that rcu_read_lock_bh() is disallowed if the CPU is either idle or
* offline from an RCU perspective, so check for those as well.
*/
int rcu_read_lock_bh_held(void)
{
- if (!debug_lockdep_rcu_enabled())
- return 1;
- if (!rcu_is_watching())
- return 0;
- if (!rcu_lockdep_current_cpu_online())
- return 0;
+ bool ret;
+
+ if (rcu_read_lock_held_common(&ret))
+ return ret;
return in_softirq() || irqs_disabled();
}
EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
+int rcu_read_lock_any_held(void)
+{
+ bool ret;
+
+ if (rcu_read_lock_held_common(&ret))
+ return ret;
+ if (lock_is_held(&rcu_lock_map) ||
+ lock_is_held(&rcu_bh_lock_map) ||
+ lock_is_held(&rcu_sched_lock_map))
+ return 1;
+ return !preemptible();
+}
+EXPORT_SYMBOL_GPL(rcu_read_lock_any_held);
+
#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
/**
@@ -336,11 +346,10 @@
int i;
int j;
- /* Initialize and register callbacks for each flavor specified. */
+ /* Initialize and register callbacks for each crcu_array element. */
for (i = 0; i < n; i++) {
if (checktiny &&
- (crcu_array[i] == call_rcu ||
- crcu_array[i] == call_rcu_bh)) {
+ (crcu_array[i] == call_rcu)) {
might_sleep();
continue;
}
@@ -356,8 +365,7 @@
/* Wait for all callbacks to be invoked. */
for (i = 0; i < n; i++) {
if (checktiny &&
- (crcu_array[i] == call_rcu ||
- crcu_array[i] == call_rcu_bh))
+ (crcu_array[i] == call_rcu))
continue;
for (j = 0; j < i; j++)
if (crcu_array[j] == crcu_array[i])
@@ -440,68 +448,27 @@
do { } while (0)
#endif
-#ifdef CONFIG_RCU_STALL_COMMON
+#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST)
+/* Get rcutorture access to sched_setaffinity(). */
+long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
+{
+ int ret;
-#ifdef CONFIG_PROVE_RCU
-#define RCU_STALL_DELAY_DELTA (5 * HZ)
-#else
-#define RCU_STALL_DELAY_DELTA 0
+ ret = sched_setaffinity(pid, in_mask);
+ WARN_ONCE(ret, "%s: sched_setaffinity() returned %d\n", __func__, ret);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(rcutorture_sched_setaffinity);
#endif
+#ifdef CONFIG_RCU_STALL_COMMON
+int rcu_cpu_stall_ftrace_dump __read_mostly;
+module_param(rcu_cpu_stall_ftrace_dump, int, 0644);
int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */
EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress);
-static int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
-
module_param(rcu_cpu_stall_suppress, int, 0644);
+int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
module_param(rcu_cpu_stall_timeout, int, 0644);
-
-int rcu_jiffies_till_stall_check(void)
-{
- int till_stall_check = READ_ONCE(rcu_cpu_stall_timeout);
-
- /*
- * Limit check must be consistent with the Kconfig limits
- * for CONFIG_RCU_CPU_STALL_TIMEOUT.
- */
- if (till_stall_check < 3) {
- WRITE_ONCE(rcu_cpu_stall_timeout, 3);
- till_stall_check = 3;
- } else if (till_stall_check > 300) {
- WRITE_ONCE(rcu_cpu_stall_timeout, 300);
- till_stall_check = 300;
- }
- return till_stall_check * HZ + RCU_STALL_DELAY_DELTA;
-}
-
-void rcu_sysrq_start(void)
-{
- if (!rcu_cpu_stall_suppress)
- rcu_cpu_stall_suppress = 2;
-}
-
-void rcu_sysrq_end(void)
-{
- if (rcu_cpu_stall_suppress == 2)
- rcu_cpu_stall_suppress = 0;
-}
-
-static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr)
-{
- rcu_cpu_stall_suppress = 1;
- return NOTIFY_DONE;
-}
-
-static struct notifier_block rcu_panic_block = {
- .notifier_call = rcu_panic,
-};
-
-static int __init check_cpu_stall_init(void)
-{
- atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block);
- return 0;
-}
-early_initcall(check_cpu_stall_init);
-
#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
#ifdef CONFIG_TASKS_RCU
@@ -701,19 +668,19 @@
/*
* Wait for all pre-existing t->on_rq and t->nvcsw
- * transitions to complete. Invoking synchronize_sched()
+ * transitions to complete. Invoking synchronize_rcu()
* suffices because all these transitions occur with
- * interrupts disabled. Without this synchronize_sched(),
+ * interrupts disabled. Without this synchronize_rcu(),
* a read-side critical section that started before the
* grace period might be incorrectly seen as having started
* after the grace period.
*
- * This synchronize_sched() also dispenses with the
+ * This synchronize_rcu() also dispenses with the
* need for a memory barrier on the first store to
* ->rcu_tasks_holdout, as it forces the store to happen
* after the beginning of the grace period.
*/
- synchronize_sched();
+ synchronize_rcu();
/*
* There were callbacks, so we need to wait for an
@@ -740,7 +707,7 @@
* This does only part of the job, ensuring that all
* tasks that were previously exiting reach the point
* where they have disabled preemption, allowing the
- * later synchronize_sched() to finish the job.
+ * later synchronize_rcu() to finish the job.
*/
synchronize_srcu(&tasks_rcu_exit_srcu);
@@ -790,20 +757,20 @@
* cause their RCU-tasks read-side critical sections to
* extend past the end of the grace period. However,
* because these ->nvcsw updates are carried out with
- * interrupts disabled, we can use synchronize_sched()
+ * interrupts disabled, we can use synchronize_rcu()
* to force the needed ordering on all such CPUs.
*
- * This synchronize_sched() also confines all
+ * This synchronize_rcu() also confines all
* ->rcu_tasks_holdout accesses to be within the grace
* period, avoiding the need for memory barriers for
* ->rcu_tasks_holdout accesses.
*
- * In addition, this synchronize_sched() waits for exiting
+ * In addition, this synchronize_rcu() waits for exiting
* tasks to complete their final preempt_disable() region
* of execution, cleaning up after the synchronize_srcu()
* above.
*/
- synchronize_sched();
+ synchronize_rcu();
/* Invoke the callbacks. */
while (list) {
@@ -825,7 +792,8 @@
struct task_struct *t;
t = kthread_run(rcu_tasks_kthread, NULL, "rcu_tasks_kthread");
- BUG_ON(IS_ERR(t));
+ if (WARN_ONCE(IS_ERR(t), "%s: Could not start Tasks-RCU grace-period kthread, OOM is now expected behavior\n", __func__))
+ return 0;
smp_mb(); /* Ensure others see full kthread. */
WRITE_ONCE(rcu_tasks_kthread_ptr, t);
return 0;
@@ -870,15 +838,10 @@
#ifdef CONFIG_PROVE_RCU
/*
- * Early boot self test parameters, one for each flavor
+ * Early boot self test parameters.
*/
static bool rcu_self_test;
-static bool rcu_self_test_bh;
-static bool rcu_self_test_sched;
-
module_param(rcu_self_test, bool, 0444);
-module_param(rcu_self_test_bh, bool, 0444);
-module_param(rcu_self_test_sched, bool, 0444);
static int rcu_self_test_counter;
@@ -888,25 +851,16 @@
pr_info("RCU test callback executed %d\n", rcu_self_test_counter);
}
+DEFINE_STATIC_SRCU(early_srcu);
+
static void early_boot_test_call_rcu(void)
{
static struct rcu_head head;
+ static struct rcu_head shead;
call_rcu(&head, test_callback);
-}
-
-static void early_boot_test_call_rcu_bh(void)
-{
- static struct rcu_head head;
-
- call_rcu_bh(&head, test_callback);
-}
-
-static void early_boot_test_call_rcu_sched(void)
-{
- static struct rcu_head head;
-
- call_rcu_sched(&head, test_callback);
+ if (IS_ENABLED(CONFIG_SRCU))
+ call_srcu(&early_srcu, &shead, test_callback);
}
void rcu_early_boot_tests(void)
@@ -915,10 +869,6 @@
if (rcu_self_test)
early_boot_test_call_rcu();
- if (rcu_self_test_bh)
- early_boot_test_call_rcu_bh();
- if (rcu_self_test_sched)
- early_boot_test_call_rcu_sched();
rcu_test_sync_prims();
}
@@ -930,16 +880,11 @@
if (rcu_self_test) {
early_boot_test_counter++;
rcu_barrier();
+ if (IS_ENABLED(CONFIG_SRCU)) {
+ early_boot_test_counter++;
+ srcu_barrier(&early_srcu);
+ }
}
- if (rcu_self_test_bh) {
- early_boot_test_counter++;
- rcu_barrier_bh();
- }
- if (rcu_self_test_sched) {
- early_boot_test_counter++;
- rcu_barrier_sched();
- }
-
if (rcu_self_test_counter != early_boot_test_counter) {
WARN_ON(1);
ret = -1;