From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751249AbVH2R5O (ORCPT ); Mon, 29 Aug 2005 13:57:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751246AbVH2R5N (ORCPT ); Mon, 29 Aug 2005 13:57:13 -0400 Received: from mtagate1.de.ibm.com ([195.212.29.150]:49120 "EHLO mtagate1.de.ibm.com") by vger.kernel.org with ESMTP id S1751247AbVH2R5L (ORCPT ); Mon, 29 Aug 2005 13:57:11 -0400 Date: Mon, 29 Aug 2005 19:57:06 +0200 From: Martin Schwidefsky To: akpm@osdl.org, heiko.carstens@de.ibm.com, linux-kernel@vger.kernel.org Subject: [patch 9/10] s390: spinlock corner case. Message-ID: <20050829175706.GI6796@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.10i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org [patch 9/10] s390: spinlock corner case. From: Heiko Carstens 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 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;