From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751431AbWE2Viy (ORCPT ); Mon, 29 May 2006 17:38:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751334AbWE2ViH (ORCPT ); Mon, 29 May 2006 17:38:07 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:49592 "EHLO mx3.mail.elte.hu") by vger.kernel.org with ESMTP id S1751327AbWE2VZZ (ORCPT ); Mon, 29 May 2006 17:25:25 -0400 Date: Mon, 29 May 2006 23:25:45 +0200 From: Ingo Molnar To: linux-kernel@vger.kernel.org Cc: Arjan van de Ven , Andrew Morton Subject: [patch 32/61] lock validator: do not recurse in printk() Message-ID: <20060529212545.GF3155@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060529212109.GA2058@elte.hu> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=AWL autolearn=no SpamAssassin version=3.0.3 0.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Ingo Molnar make printk()-ing from within the lock validation code safer by using the lockdep-recursion counter. Signed-off-by: Ingo Molnar Signed-off-by: Arjan van de Ven --- kernel/printk.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) Index: linux/kernel/printk.c =================================================================== --- linux.orig/kernel/printk.c +++ linux/kernel/printk.c @@ -516,7 +516,9 @@ asmlinkage int vprintk(const char *fmt, zap_locks(); /* This stops the holder of console_sem just where we want him */ - spin_lock_irqsave(&logbuf_lock, flags); + local_irq_save(flags); + current->lockdep_recursion++; + spin_lock(&logbuf_lock); printk_cpu = smp_processor_id(); /* Emit the output into the temporary buffer */ @@ -586,7 +588,7 @@ asmlinkage int vprintk(const char *fmt, */ console_locked = 1; printk_cpu = UINT_MAX; - spin_unlock_irqrestore(&logbuf_lock, flags); + spin_unlock(&logbuf_lock); /* * Console drivers may assume that per-cpu resources have @@ -602,6 +604,8 @@ asmlinkage int vprintk(const char *fmt, console_locked = 0; up(&console_sem); } + current->lockdep_recursion--; + local_irq_restore(flags); } else { /* * Someone else owns the drivers. We drop the spinlock, which @@ -609,7 +613,9 @@ asmlinkage int vprintk(const char *fmt, * console drivers with the output which we just produced. */ printk_cpu = UINT_MAX; - spin_unlock_irqrestore(&logbuf_lock, flags); + spin_unlock(&logbuf_lock); + current->lockdep_recursion--; + local_irq_restore(flags); } preempt_enable(); @@ -783,7 +789,13 @@ void release_console_sem(void) up(&console_sem); spin_unlock_irqrestore(&logbuf_lock, flags); if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait)) - wake_up_interruptible(&log_wait); + /* + * If we printk from within the lock dependency code, + * from within the scheduler code, then do not lock + * up due to self-recursion: + */ + if (current->lockdep_recursion <= 1) + wake_up_interruptible(&log_wait); } EXPORT_SYMBOL(release_console_sem);