Messages in this thread Patch in this message | | | Date | Mon, 29 Aug 2005 19:57:06 +0200 | From | Martin Schwidefsky <> | Subject | [patch 9/10] s390: spinlock corner case. |
| |
[patch 9/10] s390: spinlock corner case.
From: Heiko Carstens <heiko.carstens@de.ibm.com>
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 <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diffstat: include/asm-s390/spinlock.h | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)
diff -urpN linux-2.6/include/asm-s390/spinlock.h linux-2.6-patched/include/asm-s390/spinlock.h --- linux-2.6/include/asm-s390/spinlock.h 2005-08-29 01:41:01.000000000 +0200 +++ linux-2.6-patched/include/asm-s390/spinlock.h 2005-08-29 19:18:12.000000000 +0200 @@ -47,7 +47,7 @@ extern int _raw_spin_trylock_retry(spinl 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(spinlo 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; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |