Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758039AbaD3IdJ (ORCPT ); Wed, 30 Apr 2014 04:33:09 -0400 Received: from mga02.intel.com ([134.134.136.20]:25461 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751818AbaD3IdH (ORCPT ); Wed, 30 Apr 2014 04:33:07 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,956,1389772800"; d="scan'208";a="503579686" Subject: [PATCH] lib/spinlock_debug: Tweak the loop time to fit different _delay() From: "Wang, Xiaoming" To: peterz@infradead.org, mingo@redhat.com, linux-kernel@vger.kernel.org Cc: chuansheng.liu@intel.com, xiaoming.wang@intel.com Content-Type: text/plain; charset="UTF-8" Date: Wed, 30 Apr 2014 18:40:38 -0400 Message-ID: <1398897638.21870.8.camel@wxm-ubuntu> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org loops_per_jiffy*Hz is not always 1 second exactly it depends on the realization of _delay() . delay_tsc is used as _delay() in arch/x86/lib/delay.c It makes loop loops_per_jiffy larger than exception and causes one thread can not obtain the spin lock for a long time which may trigger HARD LOCKUP in this case. So we use cpu_clock() which is more accurate. Signed-off-by: Chuansheng Liu Signed-off-by: xiaoming wang --- kernel/locking/spinlock_debug.c | 9 ++++++--- 1 files changed, 6 insertions(+), 3 deletions(-) diff --git a/kernel/locking/spinlock_debug.c b/kernel/locking/spinlock_debug.c index 0374a59..471d26c 100644 --- a/kernel/locking/spinlock_debug.c +++ b/kernel/locking/spinlock_debug.c @@ -105,10 +105,13 @@ static inline void debug_spin_unlock(raw_spinlock_t *lock) static void __spin_lock_debug(raw_spinlock_t *lock) { - u64 i; - u64 loops = loops_per_jiffy * HZ; + u64 t; + u64 one_second = 1000000000; + u32 this_cpu = raw_smp_processor_id(); + + t = cpu_clock(this_cpu); - for (i = 0; i < loops; i++) { + while (cpu_clock(this_cpu) - t < one_second) { if (arch_spin_trylock(&lock->raw_lock)) return; __delay(1); -- 1.7.1 -- 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/