Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751106AbWJVP5u (ORCPT ); Sun, 22 Oct 2006 11:57:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751118AbWJVP5u (ORCPT ); Sun, 22 Oct 2006 11:57:50 -0400 Received: from taganka54-host.corbina.net ([213.234.233.54]:4241 "EHLO mail.screens.ru") by vger.kernel.org with ESMTP id S1751106AbWJVP5t (ORCPT ); Sun, 22 Oct 2006 11:57:49 -0400 Date: Sun, 22 Oct 2006 19:57:35 +0400 From: Oleg Nesterov To: Andrew Morton Cc: Peter Zijlstra , Alan Cox , linux-kernel@vger.kernel.org Subject: [PATCH] do_task_stat: don't take tty_mutex Message-ID: <20061022155735.GA10491@oleg> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1422 Lines: 47 Depends on tty-signal-tty-locking.patch ->signal->tty is protected by ->siglock, no need to take the global tty_mutex. Signed-off-by: Oleg Nesterov --- rc2-mm2/fs/proc/array.c~ 2006-10-22 19:28:17.000000000 +0400 +++ rc2-mm2/fs/proc/array.c 2006-10-22 19:45:52.000000000 +0400 @@ -346,20 +346,13 @@ static int do_task_stat(struct task_stru sigemptyset(&sigcatch); cutime = cstime = utime = stime = cputime_zero; - mutex_lock(&tty_mutex); rcu_read_lock(); if (lock_task_sighand(task, &flags)) { struct signal_struct *sig = task->signal; - struct tty_struct *tty = sig->tty; - if (tty) { - /* - * sig->tty is not stable, but tty_mutex - * protects us from release_dev(tty) - */ - barrier(); - tty_pgrp = tty->pgrp; - tty_nr = new_encode_dev(tty_devnum(tty)); + if (sig->tty) { + tty_pgrp = sig->tty->pgrp; + tty_nr = new_encode_dev(tty_devnum(sig->tty)); } num_threads = atomic_read(&sig->count); @@ -395,7 +388,6 @@ static int do_task_stat(struct task_stru unlock_task_sighand(task, &flags); } rcu_read_unlock(); - mutex_unlock(&tty_mutex); if (!whole || num_threads<2) wchan = get_wchan(task); - 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/