From: tip-bot for Peter Zijlstra <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: hpa@zytor.com, peterz@infradead.org,
linux-kernel@vger.kernel.org, mingo@kernel.org,
tglx@linutronix.de
Subject: [tip:sched/hrtimers] lockdep: Implement lock pinning
Date: Thu, 18 Jun 2015 16:03:51 -0700 [thread overview]
Message-ID: <tip-a24fc60d63da2b0b31bf7c876d12a51ed4b778bd@git.kernel.org> (raw)
In-Reply-To: <20150611124743.906731065@infradead.org>
Commit-ID: a24fc60d63da2b0b31bf7c876d12a51ed4b778bd
Gitweb: http://git.kernel.org/tip/a24fc60d63da2b0b31bf7c876d12a51ed4b778bd
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Thu, 11 Jun 2015 14:46:53 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 19 Jun 2015 00:25:27 +0200
lockdep: Implement lock pinning
Add a lockdep annotation that WARNs if you 'accidentially' unlock a
lock.
This is especially helpful for code with callbacks, where the upper
layer assumes a lock remains taken but a lower layer thinks it maybe
can drop and reacquire the lock.
By unwittingly breaking up the lock, races can be introduced.
Lock pinning is a lockdep annotation that helps with this, when you
lockdep_pin_lock() a held lock, any unlock without a
lockdep_unpin_lock() will produce a WARN. Think of this as a relative
of lockdep_assert_held(), except you don't only assert its held now,
but ensure it stays held until you release your assertion.
RFC: a possible alternative API would be something like:
int cookie = lockdep_pin_lock(&foo);
...
lockdep_unpin_lock(&foo, cookie);
Where we pick a random number for the pin_count; this makes it
impossible to sneak a lock break in without also passing the right
cookie along.
I've not done this because it ends up generating code for !LOCKDEP,
esp. if you need to pass the cookie around for some reason.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: ktkhai@parallels.com
Cc: rostedt@goodmis.org
Cc: juri.lelli@gmail.com
Cc: pang.xunlei@linaro.org
Cc: oleg@redhat.com
Cc: wanpeng.li@linux.intel.com
Cc: umgwanakikbuti@gmail.com
Link: http://lkml.kernel.org/r/20150611124743.906731065@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/lockdep.h | 10 ++++++
kernel/locking/lockdep.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 90 insertions(+)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 066ba41..c5b6b58 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -255,6 +255,7 @@ struct held_lock {
unsigned int check:1; /* see lock_acquire() comment */
unsigned int hardirqs_off:1;
unsigned int references:12; /* 32 bits */
+ unsigned int pin_count;
};
/*
@@ -354,6 +355,9 @@ extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
extern void lockdep_clear_current_reclaim_state(void);
extern void lockdep_trace_alloc(gfp_t mask);
+extern void lock_pin_lock(struct lockdep_map *lock);
+extern void lock_unpin_lock(struct lockdep_map *lock);
+
# define INIT_LOCKDEP .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0,
#define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
@@ -368,6 +372,9 @@ extern void lockdep_trace_alloc(gfp_t mask);
#define lockdep_recursing(tsk) ((tsk)->lockdep_recursion)
+#define lockdep_pin_lock(l) lock_pin_lock(&(l)->dep_map)
+#define lockdep_unpin_lock(l) lock_unpin_lock(&(l)->dep_map)
+
#else /* !CONFIG_LOCKDEP */
static inline void lockdep_off(void)
@@ -420,6 +427,9 @@ struct lock_class_key { };
#define lockdep_recursing(tsk) (0)
+#define lockdep_pin_lock(l) do { (void)(l); } while (0)
+#define lockdep_unpin_lock(l) do { (void)(l); } while (0)
+
#endif /* !LOCKDEP */
#ifdef CONFIG_LOCK_STAT
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index a266d51..18f9f43 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3157,6 +3157,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
hlock->waittime_stamp = 0;
hlock->holdtime_stamp = lockstat_clock();
#endif
+ hlock->pin_count = 0;
if (check && !mark_irqflags(curr, hlock))
return 0;
@@ -3403,6 +3404,8 @@ found_it:
if (hlock->instance == lock)
lock_release_holdtime(hlock);
+ WARN(hlock->pin_count, "releasing a pinned lock\n");
+
if (hlock->references) {
hlock->references--;
if (hlock->references) {
@@ -3459,6 +3462,49 @@ static int __lock_is_held(struct lockdep_map *lock)
return 0;
}
+static void __lock_pin_lock(struct lockdep_map *lock)
+{
+ struct task_struct *curr = current;
+ int i;
+
+ if (unlikely(!debug_locks))
+ return;
+
+ for (i = 0; i < curr->lockdep_depth; i++) {
+ struct held_lock *hlock = curr->held_locks + i;
+
+ if (match_held_lock(hlock, lock)) {
+ hlock->pin_count++;
+ return;
+ }
+ }
+
+ WARN(1, "pinning an unheld lock\n");
+}
+
+static void __lock_unpin_lock(struct lockdep_map *lock)
+{
+ struct task_struct *curr = current;
+ int i;
+
+ if (unlikely(!debug_locks))
+ return;
+
+ for (i = 0; i < curr->lockdep_depth; i++) {
+ struct held_lock *hlock = curr->held_locks + i;
+
+ if (match_held_lock(hlock, lock)) {
+ if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
+ return;
+
+ hlock->pin_count--;
+ return;
+ }
+ }
+
+ WARN(1, "unpinning an unheld lock\n");
+}
+
/*
* Check whether we follow the irq-flags state precisely:
*/
@@ -3582,6 +3628,40 @@ int lock_is_held(struct lockdep_map *lock)
}
EXPORT_SYMBOL_GPL(lock_is_held);
+void lock_pin_lock(struct lockdep_map *lock)
+{
+ unsigned long flags;
+
+ if (unlikely(current->lockdep_recursion))
+ return;
+
+ raw_local_irq_save(flags);
+ check_flags(flags);
+
+ current->lockdep_recursion = 1;
+ __lock_pin_lock(lock);
+ current->lockdep_recursion = 0;
+ raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_pin_lock);
+
+void lock_unpin_lock(struct lockdep_map *lock)
+{
+ unsigned long flags;
+
+ if (unlikely(current->lockdep_recursion))
+ return;
+
+ raw_local_irq_save(flags);
+ check_flags(flags);
+
+ current->lockdep_recursion = 1;
+ __lock_unpin_lock(lock);
+ current->lockdep_recursion = 0;
+ raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(lock_unpin_lock);
+
void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
{
current->lockdep_reclaim_gfp = gfp_mask;
next prev parent reply other threads:[~2015-06-18 23:04 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-11 12:46 [PATCH 00/18] sched: balance callbacks v4 Peter Zijlstra
2015-06-11 12:46 ` [PATCH 01/18] sched: Replace post_schedule with a balance callback list Peter Zijlstra
2015-06-11 15:32 ` Kirill Tkhai
2015-06-18 23:00 ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 02/18] sched: Use replace normalize_task() with __sched_setscheduler() Peter Zijlstra
2015-06-18 23:00 ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 03/18] sched: Allow balance callbacks for check_class_changed() Peter Zijlstra
2015-06-18 23:01 ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 04/18] sched,rt: Remove return value from pull_rt_task() Peter Zijlstra
2015-06-18 23:01 ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 05/18] sched,rt: Convert switched_{from,to}_rt() / prio_changed_rt() to balance callbacks Peter Zijlstra
2015-06-18 23:01 ` [tip:sched/hrtimers] sched, rt: Convert switched_{from, to}_rt() " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 06/18] sched,dl: Remove return value from pull_dl_task() Peter Zijlstra
2015-06-18 23:02 ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 07/18] sched,dl: Convert switched_{from,to}_dl() / prio_changed_dl() to balance callbacks Peter Zijlstra
2015-06-18 23:02 ` [tip:sched/hrtimers] sched, dl: Convert switched_{from, to}_dl() " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 08/18] hrtimer: Remove HRTIMER_STATE_MIGRATE Peter Zijlstra
2015-06-18 22:18 ` [tip:timers/core] " tip-bot for Oleg Nesterov
2015-06-11 12:46 ` [PATCH 09/18] hrtimer: Fix hrtimer_is_queued() hole Peter Zijlstra
2015-06-18 22:18 ` [tip:timers/core] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 10/18] seqcount: Rename write_seqcount_barrier() Peter Zijlstra
2015-06-18 22:19 ` [tip:timers/core] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 11/18] seqcount: Introduce raw_write_seqcount_barrier() Peter Zijlstra
2015-06-11 15:33 ` Paul E. McKenney
2015-06-11 21:45 ` Paul E. McKenney
2015-06-12 7:08 ` Peter Zijlstra
2015-06-12 18:59 ` Oleg Nesterov
2015-06-17 12:29 ` Peter Zijlstra
2015-06-17 14:57 ` Paul E. McKenney
2015-06-17 15:11 ` Peter Zijlstra
2015-06-17 15:42 ` Paul E. McKenney
2015-06-17 16:58 ` Peter Zijlstra
2015-06-17 15:49 ` Peter Zijlstra
2015-06-17 16:37 ` Paul E. McKenney
2015-06-17 17:11 ` Peter Zijlstra
2015-06-17 18:02 ` Paul E. McKenney
2015-06-18 9:15 ` Peter Zijlstra
2015-06-18 9:40 ` Ingo Molnar
2015-06-18 10:40 ` Peter Zijlstra
2015-06-18 16:54 ` Paul E. McKenney
2015-06-18 17:10 ` Steven Rostedt
2015-06-18 17:51 ` Paul E. McKenney
2015-06-18 22:19 ` [tip:timers/core] seqcount: Introduce raw_write_seqcount_barrier( ) tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 12/18] hrtimer: Allow hrtimer::function() to free the timer Peter Zijlstra
2015-06-18 22:19 ` [tip:timers/core] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 13/18] sched,dl: Fix sched class hopping CBS hole Peter Zijlstra
2015-06-18 23:02 ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 14/18] sched: Move code around Peter Zijlstra
2015-06-18 23:02 ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 15/18] sched: Streamline the task migration locking a little Peter Zijlstra
2015-06-18 23:03 ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 16/18] lockdep: Simplify lock_release() Peter Zijlstra
2015-06-18 23:03 ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-06-11 12:46 ` [PATCH 17/18] lockdep: Implement lock pinning Peter Zijlstra
2015-06-18 23:03 ` tip-bot for Peter Zijlstra [this message]
2015-06-11 12:46 ` [PATCH 18/18] sched,lockdep: Employ " Peter Zijlstra
2015-06-18 23:04 ` [tip:sched/hrtimers] " tip-bot for Peter Zijlstra
2015-12-29 5:41 ` [PATCH 00/18] sched: balance callbacks v4 Byungchul Park
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