From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 6BEE91A0D93 for ; Tue, 24 Feb 2015 14:30:51 +1100 (AEDT) From: Anton Blanchard To: Andrew Morton , Steven Rostedt , Michael Ellerman , Paul Mackerras , Benjamin Herrenschmidt , sam.bobroff@au1.ibm.com, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Russell King , peterz@infradead.org, Don Zickus Subject: [PATCH 6/7] dump_stack: Serialise dump_stack with die_spin_lock_{irqsave, irqrestore} Date: Tue, 24 Feb 2015 14:30:33 +1100 Message-Id: <1424748634-9153-7-git-send-email-anton@samba.org> In-Reply-To: <1424748634-9153-1-git-send-email-anton@samba.org> References: <1424748634-9153-1-git-send-email-anton@samba.org> Cc: x86@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Remove another version of a recursive lock in dump_stack. Signed-off-by: Anton Blanchard --- lib/dump_stack.c | 40 ++++------------------------------------ 1 file changed, 4 insertions(+), 36 deletions(-) diff --git a/lib/dump_stack.c b/lib/dump_stack.c index 6745c62..f64ee3c 100644 --- a/lib/dump_stack.c +++ b/lib/dump_stack.c @@ -7,7 +7,7 @@ #include #include #include -#include +#include static void __dump_stack(void) { @@ -20,44 +20,12 @@ static void __dump_stack(void) * * Architectures can override this implementation by implementing its own. */ -#ifdef CONFIG_SMP -static atomic_t dump_lock = ATOMIC_INIT(-1); - asmlinkage __visible void dump_stack(void) { - int was_locked; - int old; - int cpu; - - /* - * Permit this cpu to perform nested stack dumps while serialising - * against other CPUs - */ - preempt_disable(); - -retry: - cpu = smp_processor_id(); - old = atomic_cmpxchg(&dump_lock, -1, cpu); - if (old == -1) { - was_locked = 0; - } else if (old == cpu) { - was_locked = 1; - } else { - cpu_relax(); - goto retry; - } - - __dump_stack(); + unsigned long flags; - if (!was_locked) - atomic_set(&dump_lock, -1); - - preempt_enable(); -} -#else -asmlinkage __visible void dump_stack(void) -{ + die_spin_lock_irqsave(flags); __dump_stack(); + die_spin_unlock_irqrestore(flags); } -#endif EXPORT_SYMBOL(dump_stack); -- 2.1.0