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authorErlang/OTP <[email protected]>2015-06-25 14:28:44 +0200
committerErlang/OTP <[email protected]>2015-06-25 14:28:44 +0200
commit70a77207f03290bfff585b2e6e7930e411f6fa08 (patch)
tree34074224be2e10413cde74f9f78818f62486daa2 /erts
parenteb012e5d805c3d921186ceab32dd62374cb49981 (diff)
parent7bbb207b30360c60fb9965359635e1cd0ad70c77 (diff)
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Merge branch 'sverk/poll-lost-wakeup/OTP-12859' into maint-17
* sverk/poll-lost-wakeup/OTP-12859: erts: Fix race in poller thread wake up
Diffstat (limited to 'erts')
-rw-r--r--erts/emulator/sys/common/erl_poll.c15
1 files changed, 5 insertions, 10 deletions
diff --git a/erts/emulator/sys/common/erl_poll.c b/erts/emulator/sys/common/erl_poll.c
index aa412a20c8..e798dc11b9 100644
--- a/erts/emulator/sys/common/erl_poll.c
+++ b/erts/emulator/sys/common/erl_poll.c
@@ -410,7 +410,7 @@ static ERTS_INLINE int
is_interrupted_reset(ErtsPollSet ps)
{
#if defined(USE_THREADS) || ERTS_POLL_ASYNC_INTERRUPT_SUPPORT
- return (erts_atomic32_xchg_nob(&ps->wakeup_state, ERTS_POLL_NOT_WOKEN)
+ return (erts_atomic32_xchg_acqb(&ps->wakeup_state, ERTS_POLL_NOT_WOKEN)
== ERTS_POLL_WOKEN_INTR);
#else
return 0;
@@ -421,7 +421,7 @@ static ERTS_INLINE void
woke_up(ErtsPollSet ps)
{
#if defined(USE_THREADS) || ERTS_POLL_ASYNC_INTERRUPT_SUPPORT
- erts_aint32_t wakeup_state = erts_atomic32_read_nob(&ps->wakeup_state);
+ erts_aint32_t wakeup_state = erts_atomic32_read_acqb(&ps->wakeup_state);
if (wakeup_state == ERTS_POLL_NOT_WOKEN)
(void) erts_atomic32_cmpxchg_nob(&ps->wakeup_state,
ERTS_POLL_WOKEN,
@@ -448,14 +448,9 @@ wake_poller(ErtsPollSet ps, int interrupted, int async_signal_safe)
wakeup_state = erts_atomic32_cmpxchg_relb(&ps->wakeup_state,
ERTS_POLL_WOKEN,
ERTS_POLL_NOT_WOKEN);
- else {
- /*
- * We might unnecessarily write to the pipe, however,
- * that isn't problematic.
- */
- wakeup_state = erts_atomic32_read_nob(&ps->wakeup_state);
- erts_atomic32_set_relb(&ps->wakeup_state, ERTS_POLL_WOKEN_INTR);
- }
+ else
+ wakeup_state = erts_atomic32_xchg_relb(&ps->wakeup_state,
+ ERTS_POLL_WOKEN_INTR);
wake = wakeup_state == ERTS_POLL_NOT_WOKEN;
}
/*