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Don't retry a lost reservation in atomic_fcmpset()

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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
This commit is contained in:
Justin Hibbits 2017-01-31 03:40:13 +00:00
parent 6be2ff7d3e
commit d3a8234cef
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=313007
1 changed files with 14 additions and 14 deletions
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28
sys/powerpc/include/atomic.h
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@ -678,18 +678,18 @@ atomic_fcmpset_int(volatile u_int *p, u_int *cmpval, u_int newval)
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, u_long *cmpval, u_long newval)
__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, u_long *cmpval, u_long newval)
"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");