Because the atomic sync functions in config/pa/linux-atomic.c are not
lock free, we need to use
__kernel_cmpxchg for the __sync_lock_release. This was found in
glibc's pthread_spin_unlock
implementation.
Tested on hppa-unknown-linux-gnu. Committed to trunk.
Dave
--
John David Anglin dave.ang...@bell.net
2014-07-17 John David Anglin <dang...@gcc.gnu.org>
* config/pa/linux-atomic.c (__sync_lock_release_4): New.
(SYNC_LOCK_RELEASE): Update to use __kernel_cmpxchg for release.
Don't use SYNC_LOCK_RELEASE for int type.
Index: config/pa/linux-atomic.c
===================================================================
--- config/pa/linux-atomic.c (revision 210671)
+++ config/pa/linux-atomic.c (working copy)
@@ -293,13 +293,34 @@
SUBWORD_TEST_AND_SET (unsigned short, 2)
SUBWORD_TEST_AND_SET (unsigned char, 1)
+void HIDDEN
+__sync_lock_release_4 (int *ptr)
+{
+ int failure, oldval;
+
+ do {
+ oldval = *ptr;
+ failure = __kernel_cmpxchg (oldval, 0, ptr);
+ } while (failure != 0);
+}
+
#define SYNC_LOCK_RELEASE(TYPE, WIDTH) \
void HIDDEN \
__sync_lock_release_##WIDTH (TYPE *ptr) \
{ \
- *ptr = 0; \
+ int failure; \
+ unsigned int oldval, newval, shift, mask; \
+ int *wordptr = (int *) ((unsigned long) ptr & ~3); \
+ \
+ shift = (((unsigned long) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH; \
+ mask = MASK_##WIDTH << shift; \
+ \
+ do { \
+ oldval = *wordptr; \
+ newval = oldval & ~mask; \
+ failure = __kernel_cmpxchg (oldval, newval, wordptr); \
+ } while (failure != 0); \
}
-SYNC_LOCK_RELEASE (int, 4)
SYNC_LOCK_RELEASE (short, 2)
SYNC_LOCK_RELEASE (char, 1)
