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| author | Martin Kuchta <martin.kuchta@netapp.com> | 2018-08-27 18:54:46 +0200 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2018-08-27 18:54:46 +0200 |
| commit | aa8a3e4cdef20c50cb20f008864fff05cbfbdf29 (patch) | |
| tree | 61639ae8462af60419e1ce7254c901fb7c7c44d8 /nptl | |
| parent | c87b5bab241c8d1e7709061c6b63f1b435ee3ac9 (diff) | |
| download | glibc-aa8a3e4cdef20c50cb20f008864fff05cbfbdf29.tar.gz glibc-aa8a3e4cdef20c50cb20f008864fff05cbfbdf29.tar.xz glibc-aa8a3e4cdef20c50cb20f008864fff05cbfbdf29.zip | |
pthread_cond_broadcast: Fix waiters-after-spinning case [BZ #23538]
(cherry picked from commit 99ea93ca31795469d2a1f1570f17a5c39c2eb7e2)
Diffstat (limited to 'nptl')
| -rw-r--r-- | nptl/pthread_cond_common.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/nptl/pthread_cond_common.c b/nptl/pthread_cond_common.c index 8e425eb01e..479e54febb 100644 --- a/nptl/pthread_cond_common.c +++ b/nptl/pthread_cond_common.c @@ -405,8 +405,12 @@ __condvar_quiesce_and_switch_g1 (pthread_cond_t *cond, uint64_t wseq, { /* There is still a waiter after spinning. Set the wake-request flag and block. Relaxed MO is fine because this is just about - this futex word. */ - r = atomic_fetch_or_relaxed (cond->__data.__g_refs + g1, 1); + this futex word. + + Update r to include the set wake-request flag so that the upcoming + futex_wait only blocks if the flag is still set (otherwise, we'd + violate the basic client-side futex protocol). */ + r = atomic_fetch_or_relaxed (cond->__data.__g_refs + g1, 1) | 1; if ((r >> 1) > 0) futex_wait_simple (cond->__data.__g_refs + g1, r, private); |