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[PATCH 04/14] Disable elision for any pthread_mutexattr_settype call
- From: Andi Kleen <andi at firstfloor dot org>
- To: libc-alpha at sourceware dot org
- Cc: Andi Kleen <ak at linux dot jf dot intel dot com>
- Date: Thu, 27 Jun 2013 22:51:47 -0700
- Subject: [PATCH 04/14] Disable elision for any pthread_mutexattr_settype call
- References: <1372398717-16530-1-git-send-email-andi at firstfloor dot org>
From: Andi Kleen <ak@linux.intel.com>
PTHREAD_MUTEX_NORMAL requires deadlock for nesting, DEFAULT
does not. Since glibc uses the same value (0) disable elision
for any call to pthread_mutexattr_settype() with a 0 value.
This implies that a program can disable elision by doing
pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_NORMAL)
Based on a original proposal by Rich Felker.
nptl/:
2013-06-27 Andi Kleen <ak@linux.intel.com>
* pthread_mutexattr_settype.c (__pthread_mutexattr_settype):
Disable elision for PTHREAD_MUTEX_DEFAULT.
---
nptl/pthread_mutexattr_settype.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/nptl/pthread_mutexattr_settype.c b/nptl/pthread_mutexattr_settype.c
index 7b476e9..a85cdcb 100644
--- a/nptl/pthread_mutexattr_settype.c
+++ b/nptl/pthread_mutexattr_settype.c
@@ -30,6 +30,11 @@ __pthread_mutexattr_settype (attr, kind)
if (kind < PTHREAD_MUTEX_NORMAL || kind > PTHREAD_MUTEX_ADAPTIVE_NP)
return EINVAL;
+ /* Cannot distinguish between DEFAULT and NORMAL. So any settype
+ call disables elision for now. */
+ if (kind == PTHREAD_MUTEX_DEFAULT)
+ kind |= PTHREAD_MUTEX_NO_ELISION_NP;
+
iattr = (struct pthread_mutexattr *) attr;
iattr->mutexkind = (iattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_BITS) | kind;
--
1.8.1.4