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sched/wait: Fix signal handling in bit wait helpers

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Vladimir reported getting RCU stall warnings and bisected it back to
commit:

  743162013d ("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 <[email protected]>
Tested-by: Vladimir Murzin <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Fixes: 743162013d ("sched: Remove proliferation of wait_on_bit() action functions")
Fixes: cbbce82209 ("SCHED: add some "wait..on_bit...timeout()" interfaces.")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Peter Zijlstra authored and Ingo Molnar committed 2015-12-04 10:10:15 +01:00
1 parent 89b411081d
commit 68985633bc
1 file changed
+8 -8
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kernel/sched/wait.c
+8 -8
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@@ -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);