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authorSverker Eriksson <[email protected]>2015-06-22 22:11:16 +0200
committerSverker Eriksson <[email protected]>2015-06-22 22:12:04 +0200
commit7bbb207b30360c60fb9965359635e1cd0ad70c77 (patch)
treebe272702ec75c0389e3e2a9e4f6d0976b96c73dc
parent23790daf1a2d384b0fc11c655fa825151d9fa420 (diff)
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erts: Fix race in poller thread wake up
-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 0a58a625b2..4ac02d21d3 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;
}
/*