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.
+2013-07-02 Andi Kleen <ak@linux.intel.com>
+
+ * pthread_mutexattr_settype.c (__pthread_mutexattr_settype):
+ Disable elision for PTHREAD_MUTEX_DEFAULT.
+
2013-07-02 Andi Kleen <ak@linux.intel.com>
Hongjiu Lu <hongjiu.lu@intel.com>
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;