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GNU C Library master sources branch release/2.27/master updated. glibc-2.27-78-g2b47bb9
- From: fw at sourceware dot org
- To: glibc-cvs at sourceware dot org
- Date: 27 Aug 2018 17:12:56 -0000
- Subject: GNU C Library master sources branch release/2.27/master updated. glibc-2.27-78-g2b47bb9
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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=2b47bb9cba048e778a7d832f284feccb14a40483
commit 2b47bb9cba048e778a7d832f284feccb14a40483
Author: Martin Kuchta <martin.kuchta@netapp.com>
Date: Mon Aug 27 18:54:46 2018 +0200
pthread_cond_broadcast: Fix waiters-after-spinning case [BZ #23538]
(cherry picked from commit 99ea93ca31795469d2a1f1570f17a5c39c2eb7e2)
diff --git a/ChangeLog b/ChangeLog
index 7fcb7d5..eeb2d87 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.
+
2018-07-29 H.J. Lu <hongjiu.lu@intel.com>
[BZ #23459]
diff --git a/NEWS b/NEWS
index bc150b6..a2e31b4 100644
--- a/NEWS
+++ b/NEWS
@@ -89,6 +89,7 @@ The following bugs are resolved with this release:
[23363] stdio-common/tst-printf.c has non-free license
[23456] Wrong index_cpu_LZCNT
[23459] COMMON_CPUID_INDEX_80000001 isn't populated for Intel processors
+ [23538] pthread_cond_broadcast: Fix waiters-after-spinning case
Version 2.27
diff --git a/nptl/pthread_cond_common.c b/nptl/pthread_cond_common.c
index 8e425eb..479e54f 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);
-----------------------------------------------------------------------
Summary of changes:
ChangeLog | 8 ++++++++
NEWS | 1 +
nptl/pthread_cond_common.c | 8 ++++++--
3 files changed, 15 insertions(+), 2 deletions(-)
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