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| author | nwhitehorn <nwhitehorn@FreeBSD.org> | 2010-02-20 16:13:43 +0000 |
|---|---|---|
| committer | nwhitehorn <nwhitehorn@FreeBSD.org> | 2010-02-20 16:13:43 +0000 |
| commit | 1a4ed70d204022e6b929701d21300c4593da8513 (patch) | |
| tree | 54fc7caf881b3b1a012a7c6ef6e223507f177454 | |
| parent | 0b363d5ac3998739989ea3f6af616294d64ed696 (diff) | |
| download | FreeBSD-src-1a4ed70d204022e6b929701d21300c4593da8513.zip FreeBSD-src-1a4ed70d204022e6b929701d21300c4593da8513.tar.gz | |
Merge r198724 to Book-E. casuword() non-atomically read the current value
of its argument before atomically replacing it, which could occasionally
return the wrong value on an SMP system. This resulted in user mutex
operations hanging when using threaded applications.
| -rw-r--r-- | sys/powerpc/booke/copyinout.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/sys/powerpc/booke/copyinout.c b/sys/powerpc/booke/copyinout.c index fd3bdf3..91195dd 100644 --- a/sys/powerpc/booke/copyinout.c +++ b/sys/powerpc/booke/copyinout.c @@ -295,8 +295,19 @@ casuword(volatile u_long *addr, u_long old, u_long new) return (EFAULT); } - val = *addr; - (void) atomic_cmpset_32((volatile uint32_t *)addr, old, new); + __asm __volatile ( + "1:\tlwarx %0, 0, %2\n\t" /* load old value */ + "cmplw %3, %0\n\t" /* compare */ + "bne 2f\n\t" /* exit if not equal */ + "stwcx. %4, 0, %2\n\t" /* attempt to store */ + "bne- 1b\n\t" /* spin if failed */ + "b 3f\n\t" /* we've succeeded */ + "2:\n\t" + "stwcx. %0, 0, %2\n\t" /* clear reservation (74xx) */ + "3:\n\t" + : "=&r" (val), "=m" (*addr) + : "r" (addr), "r" (old), "r" (new), "m" (*addr) + : "cc", "memory"); td->td_pcb->pcb_onfault = NULL; |
