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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 | |
| 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)
| -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
diff --git a/ChangeLog b/ChangeLog index b9e732a192..ef83777833 100644 --- a/ChangeLog +++ b/ChangeLog @@ -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): diff --git a/NEWS b/NEWS index 873cf8f64f..3073712cba 100644 --- a/NEWS +++ b/NEWS @@ -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); |