From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933913Ab0JSJh7 (ORCPT ); Tue, 19 Oct 2010 05:37:59 -0400 Received: from mgw2.diku.dk ([130.225.96.92]:56490 "EHLO mgw2.diku.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758001Ab0JSJhY (ORCPT ); Tue, 19 Oct 2010 05:37:24 -0400 From: Julia Lawall To: linux-kernel@vger.kernel.org Cc: kernel-janitors@vger.kernel.org Subject: [PATCH 2/4] drivers/char/generic_serial.c: convert nested spin_lock_irqsave to spin_lock Date: Tue, 19 Oct 2010 11:43:54 +0200 Message-Id: <1287481436-26656-2-git-send-email-julia@diku.dk> X-Mailer: git-send-email 1.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Julia Lawall If spin_lock_irqsave is called twice in a row with the same second argument, the interrupt state at the point of the second call overwrites the value saved by the first call. Indeed, the second call does not need to save the interrupt state, so it is changed to a simple spin_lock. The semantic match that finds this problem is as follows: (http://coccinelle.lip6.fr/) // @@ expression lock1,lock2; expression flags; @@ *spin_lock_irqsave(lock1,flags) ... when != flags *spin_lock_irqsave(lock2,flags) // Signed-off-by: Julia Lawall --- drivers/char/generic_serial.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/char/generic_serial.c b/drivers/char/generic_serial.c index 5954ee1..466988d 100644 --- a/drivers/char/generic_serial.c +++ b/drivers/char/generic_serial.c @@ -566,9 +566,9 @@ void gs_close(struct tty_struct * tty, struct file * filp) * line status register. */ - spin_lock_irqsave(&port->driver_lock, flags); + spin_lock(&port->driver_lock); port->rd->disable_rx_interrupts (port); - spin_unlock_irqrestore(&port->driver_lock, flags); + spin_unlock(&port->driver_lock); spin_unlock_irqrestore(&port->port.lock, flags); /* close has no way of returning "EINTR", so discard return value */