From: Heiko Carstens Date: Sat, 3 Sep 2005 22:58:05 +0000 (-0700) Subject: [PATCH] s390: spinlock corner case X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=9513e5e3f5a6b429da8a9fd4330f71f1e547c8e0;p=linux-beck.git [PATCH] s390: spinlock corner case On s390 the lock value used for spinlocks consists of the lower 32 bits of the PSW that holds the lock. If this address happens to be on a four gigabyte boundary the lock is left unlocked. This allows other cpus to grab the same lock and enter a lock protected code path concurrently. In theory this can happen if the vmalloc area for the code of a module crosses a 4 GB boundary. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/asm-s390/spinlock.h b/include/asm-s390/spinlock.h index 8ff10300f7ee..321b23bba1ec 100644 --- a/include/asm-s390/spinlock.h +++ b/include/asm-s390/spinlock.h @@ -47,7 +47,7 @@ extern int _raw_spin_trylock_retry(spinlock_t *lp, unsigned int pc); static inline void _raw_spin_lock(spinlock_t *lp) { - unsigned long pc = (unsigned long) __builtin_return_address(0); + unsigned long pc = 1 | (unsigned long) __builtin_return_address(0); if (unlikely(_raw_compare_and_swap(&lp->lock, 0, pc) != 0)) _raw_spin_lock_wait(lp, pc); @@ -55,7 +55,7 @@ static inline void _raw_spin_lock(spinlock_t *lp) static inline int _raw_spin_trylock(spinlock_t *lp) { - unsigned long pc = (unsigned long) __builtin_return_address(0); + unsigned long pc = 1 | (unsigned long) __builtin_return_address(0); if (likely(_raw_compare_and_swap(&lp->lock, 0, pc) == 0)) return 1;