sched/wait: Fix signal handling in bit wait helpers (68985633) · Commits · 戴 / test

Vladimir reported getting RCU stall warnings and bisected it back to commit: ("sched: Remove proliferation of wait_on_bit() action functions") That commit inadvertently reversed the calls to schedule() and signal_pending(), thereby not handling the case where the signal receives while we sleep. Reported-by:

Vladimir Murzin <vladimir.murzin@arm.com> Tested-by:

Vladimir Murzin <vladimir.murzin@arm.com> Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: mark.rutland@arm.com Cc: neilb@suse.de Cc: oleg@redhat.com Fixes: ("sched: Remove proliferation of wait_on_bit() action functions") Fixes: ("SCHED: add some "wait..on_bit...timeout()" interfaces.") Link: http://lkml.kernel.org/r/20151201130404.GL3816@twins.programming.kicks-ass.net Signed-off-by:

Ingo Molnar <mingo@kernel.org>

kernel/sched/wait.c

+8 −8

Original line number	Diff line number	Diff line
		@@ -583,18 +583,18 @@ EXPORT_SYMBOL(wake_up_atomic_t);

		__sched int bit_wait(struct wait_bit_key *word)
		{
		if (signal_pending_state(current->state, current))
		return 1;
		schedule();
		if (signal_pending(current))
		return -EINTR;
		return 0;
		}
		EXPORT_SYMBOL(bit_wait);

		__sched int bit_wait_io(struct wait_bit_key *word)
		{
		if (signal_pending_state(current->state, current))
		return 1;
		io_schedule();
		if (signal_pending(current))
		return -EINTR;
		return 0;
		}
		EXPORT_SYMBOL(bit_wait_io);
		@@ -602,11 +602,11 @@ EXPORT_SYMBOL(bit_wait_io);
		__sched int bit_wait_timeout(struct wait_bit_key *word)
		{
		unsigned long now = READ_ONCE(jiffies);
		if (signal_pending_state(current->state, current))
		return 1;
		if (time_after_eq(now, word->timeout))
		return -EAGAIN;
		schedule_timeout(word->timeout - now);
		if (signal_pending(current))
		return -EINTR;
		return 0;
		}
		EXPORT_SYMBOL_GPL(bit_wait_timeout);
		@@ -614,11 +614,11 @@ EXPORT_SYMBOL_GPL(bit_wait_timeout);
		__sched int bit_wait_io_timeout(struct wait_bit_key *word)
		{
		unsigned long now = READ_ONCE(jiffies);
		if (signal_pending_state(current->state, current))
		return 1;
		if (time_after_eq(now, word->timeout))
		return -EAGAIN;
		io_schedule_timeout(word->timeout - now);
		if (signal_pending(current))
		return -EINTR;
		return 0;
		}
		EXPORT_SYMBOL_GPL(bit_wait_io_timeout);

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