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| author |   Martin Kuchta <martin.kuchta@netapp.com> | 2018-08-27 18:54:46 +0200 |
|---|---|---|
| committer |   Andreas K. Hüttel <dilfridge@gentoo.org> | 2018-10-21 17:41:05 +0200 |
| commit | db9966ce096b68e81efd82d461a8ffa9e89e1bda (patch) | |
| tree | 92b017fb16d124add1db9479e2310c0254afc759 | |
| parent | Improve ChangeLog message. (diff) | |
| download | glibc-db9966ce096b68e81efd82d461a8ffa9e89e1bda.tar.gz glibc-db9966ce096b68e81efd82d461a8ffa9e89e1bda.tar.bz2 glibc-db9966ce096b68e81efd82d461a8ffa9e89e1bda.zip | |
pthread_cond_broadcast: Fix waiters-after-spinning case [BZ #23538]
(cherry picked from commit 99ea93ca31795469d2a1f1570f17a5c39c2eb7e2)
(cherry picked from commit aa8a3e4cdef20c50cb20f008864fff05cbfbdf29)
| -rw-r--r-- | ChangeLog | 8 | ||||
| -rw-r--r-- | NEWS | 1 | ||||
| -rw-r--r-- | nptl/pthread_cond_common.c | 8 |
3 files changed, 15 insertions, 2 deletions
@@ -1,3 +1,11 @@ +2018-08-27 Martin Kuchta <martin.kuchta@netapp.com> + Torvald Riegel <triegel@redhat.com> + + [BZ #23538] + * nptl/pthread_cond_common.c (__condvar_quiesce_and_switch_g1): + Update r to include the set wake-request flag if waiters are + remaining after spinning. + 2018-08-03 DJ Delorie <dj@redhat.com> * sysdeps/riscv/rvf/math_private.h (libc_feholdexcept_setround_riscv): @@ -11,6 +11,7 @@ The following bugs are resolved with this release: [23497] readdir64@GLIBC_2.1 cannot parse the kernel directory stream [23521] nss_files aliases database file stream leak + [23538] pthread_cond_broadcast: Fix waiters-after-spinning case Version 2.28 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); |