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[PATCH] Properly handle forced elision in pthread_mutex_trylock
- From: Andreas Schwab <schwab at suse dot de>
- To: libc-alpha at sourceware dot org
- Date: Tue, 09 Dec 2014 16:24:13 +0100
- Subject: [PATCH] Properly handle forced elision in pthread_mutex_trylock
- Authentication-results: sourceware.org; auth=none
According to https://sourceware.org/bugzilla/show_bug.cgi?id=16657#c10
this is the correct solution.
Andreas.
[BZ #16657]
* nptl/pthread_mutex_trylock.c (__pthread_mutex_trylock): Use
FORCE_ELISION instead of DO_ELISION.
* sysdeps/unix/sysv/linux/x86/force-elision.h (DO_ELISION):
Remove.
* sysdeps/unix/sysv/linux/s390/force-elision.h (DO_ELISION):
Likewise.
---
nptl/pthread_mutex_trylock.c | 10 +++-------
sysdeps/unix/sysv/linux/s390/force-elision.h | 5 -----
sysdeps/unix/sysv/linux/x86/force-elision.h | 5 -----
3 files changed, 3 insertions(+), 17 deletions(-)
diff --git a/nptl/pthread_mutex_trylock.c b/nptl/pthread_mutex_trylock.c
index 0293d0f..c4622aa 100644
--- a/nptl/pthread_mutex_trylock.c
+++ b/nptl/pthread_mutex_trylock.c
@@ -26,13 +26,10 @@
#define lll_trylock_elision(a,t) lll_trylock(a)
#endif
-#ifndef DO_ELISION
-#define DO_ELISION(m) 0
+#ifndef FORCE_ELISION
+#define FORCE_ELISION(m, s)
#endif
-/* We don't force elision in trylock, because this can lead to inconsistent
- lock state if the lock was actually busy. */
-
int
__pthread_mutex_trylock (mutex)
pthread_mutex_t *mutex;
@@ -77,8 +74,7 @@ __pthread_mutex_trylock (mutex)
return 0;
case PTHREAD_MUTEX_TIMED_NP:
- if (DO_ELISION (mutex))
- goto elision;
+ FORCE_ELISION (mutex, goto elision);
/*FALL THROUGH*/
case PTHREAD_MUTEX_ADAPTIVE_NP:
case PTHREAD_MUTEX_ERRORCHECK_NP:
diff --git a/sysdeps/unix/sysv/linux/s390/force-elision.h b/sysdeps/unix/sysv/linux/s390/force-elision.h
index 8fd7684..31b3662 100644
--- a/sysdeps/unix/sysv/linux/s390/force-elision.h
+++ b/sysdeps/unix/sysv/linux/s390/force-elision.h
@@ -17,11 +17,6 @@
<http://www.gnu.org/licenses/>. */
#ifdef ENABLE_LOCK_ELISION
-/* Check for elision on this lock without upgrading. */
-#define DO_ELISION(m) \
- (__pthread_force_elision \
- && (m->__data.__kind & PTHREAD_MUTEX_NO_ELISION_NP) == 0) \
-
/* Automatically enable elision for existing user lock kinds. */
#define FORCE_ELISION(m, s) \
if (__pthread_force_elision \
diff --git a/sysdeps/unix/sysv/linux/x86/force-elision.h b/sysdeps/unix/sysv/linux/x86/force-elision.h
index 945f886..a767cf1 100644
--- a/sysdeps/unix/sysv/linux/x86/force-elision.h
+++ b/sysdeps/unix/sysv/linux/x86/force-elision.h
@@ -16,11 +16,6 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
-/* Check for elision on this lock without upgrading. */
-#define DO_ELISION(m) \
- (__pthread_force_elision \
- && (m->__data.__kind & PTHREAD_MUTEX_NO_ELISION_NP) == 0) \
-
/* Automatically enable elision for existing user lock kinds. */
#define FORCE_ELISION(m, s) \
if (__pthread_force_elision \
--
2.2.0
--
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."