Author: jhibbits
Date: Tue Jan 31 03:40:13 2017
New Revision: 313007
URL: https://svnweb.freebsd.org/changeset/base/313007
Log:
Don't retry a lost reservation in atomic_fcmpset()
The desired behavior of atomic_fcmpset_() is to always exit on error. Instead
of retrying on lost reservation, leave the retry to the caller, and return
error.
Reported by: kib
Modified:
head/sys/powerpc/include/atomic.h
Modified: head/sys/powerpc/include/atomic.h
==============================================================================
--- head/sys/powerpc/include/atomic.h Tue Jan 31 03:26:32 2017
(r313006)
+++ head/sys/powerpc/include/atomic.h Tue Jan 31 03:40:13 2017
(r313007)
@@ -678,18 +678,18 @@ atomic_fcmpset_int(volatile u_int *p, u_
int ret;
__asm __volatile (
- "1:\tlwarx %0, 0, %3\n\t" /* load old value */
+ "lwarx %0, 0, %3\n\t" /* load old value */
"cmplw %4, %0\n\t" /* compare */
- "bne 2f\n\t" /* exit if not equal */
+ "bne 1f\n\t" /* exit if not equal */
"stwcx. %5, 0, %3\n\t" /* attempt to store */
- "bne- 1b\n\t" /* spin if failed */
+ "bne- 1f\n\t" /* exit if failed */
"li %0, 1\n\t" /* success - retval = 1 */
- "b 3f\n\t" /* we've succeeded */
- "2:\n\t"
+ "b 2f\n\t" /* we've succeeded */
+ "1:\n\t"
"stwcx. %0, 0, %3\n\t" /* clear reservation (74xx) */
"stwx %0, 0, %7\n\t"
"li %0, 0\n\t" /* failure - retval = 0 */
- "3:\n\t"
+ "2:\n\t"
: "=&r" (ret), "=m" (*p), "=m" (*cmpval)
: "r" (p), "r" (*cmpval), "r" (newval), "m" (*p), "r"(cmpval)
: "cr0", "memory");
@@ -703,20 +703,20 @@ atomic_fcmpset_long(volatile u_long *p,
__asm __volatile (
#ifdef __powerpc64__
- "1:\tldarx %0, 0, %3\n\t" /* load old value */
+ "ldarx %0, 0, %3\n\t" /* load old value */
"cmpld %4, %0\n\t" /* compare */
- "bne 2f\n\t" /* exit if not equal */
+ "bne 1f\n\t" /* exit if not equal */
"stdcx. %5, 0, %3\n\t" /* attempt to store */
#else
- "1:\tlwarx %0, 0, %3\n\t" /* load old value */
+ "lwarx %0, 0, %3\n\t" /* load old value */
"cmplw %4, %0\n\t" /* compare */
- "bne 2f\n\t" /* exit if not equal */
+ "bne 1f\n\t" /* exit if not equal */
"stwcx. %5, 0, %3\n\t" /* attempt to store */
#endif
- "bne- 1b\n\t" /* spin if failed */
+ "bne- 1f\n\t" /* exit if failed */
"li %0, 1\n\t" /* success - retval = 1 */
- "b 3f\n\t" /* we've succeeded */
- "2:\n\t"
+ "b 2f\n\t" /* we've succeeded */
+ "1:\n\t"
#ifdef __powerpc64__
"stdcx. %0, 0, %3\n\t" /* clear reservation (74xx) */
"stdx %0, 0, %7\n\t"
@@ -725,7 +725,7 @@ atomic_fcmpset_long(volatile u_long *p,
"stwx %0, 0, %7\n\t"
#endif
"li %0, 0\n\t" /* failure - retval = 0 */
- "3:\n\t"
+ "2:\n\t"
: "=&r" (ret), "=m" (*p), "=m" (*cmpval)
: "r" (p), "r" (*cmpval), "r" (newval), "m" (*p), "r"(cmpval)
: "cr0", "memory");
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