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authorFrederic Weisbecker <frederic@kernel.org>2021-07-26 14:55:08 +0200
committerThomas Gleixner <tglx@linutronix.de>2021-08-10 17:09:58 +0200
commita5dec9f82ab2ae486119f0b0820ea16db3e522c3 (patch)
tree6ba9fc20e0122ca3b6deb481e0e2bc6942cd8a17 /kernel/signal.c
parent1dae37c7e41d9a75a615ba7b0480acc2e04094d4 (diff)
posix-cpu-timers: Assert task sighand is locked while starting cputime counter
Starting the process wide cputime counter needs to be done in the same sighand locking sequence than actually arming the related timer otherwise this races against concurrent timers setting/expiring in the same threadgroup. Detecting that the cputime counter is started without holding the sighand lock is a first step toward debugging such situations. Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210726125513.271824-2-frederic@kernel.org
Diffstat (limited to 'kernel/signal.c')
-rw-r--r--kernel/signal.c15
1 files changed, 15 insertions, 0 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index a3229add4455..52b6abec0ff8 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1413,6 +1413,21 @@ struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
return sighand;
}
+#ifdef CONFIG_LOCKDEP
+void lockdep_assert_task_sighand_held(struct task_struct *task)
+{
+ struct sighand_struct *sighand;
+
+ rcu_read_lock();
+ sighand = rcu_dereference(task->sighand);
+ if (sighand)
+ lockdep_assert_held(&sighand->siglock);
+ else
+ WARN_ON_ONCE(1);
+ rcu_read_unlock();
+}
+#endif
+
/*
* send signal info to all the members of a group
*/

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