From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932878AbXCRTEG (ORCPT ); Sun, 18 Mar 2007 15:04:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932991AbXCRTEF (ORCPT ); Sun, 18 Mar 2007 15:04:05 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:36904 "EHLO ebiederm.dsl.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932878AbXCRTEE (ORCPT ); Sun, 18 Mar 2007 15:04:04 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Andrew Morton Cc: "Linux Kernel Mailing List" , "Catalin Marinas" Subject: [PATCH 2/4] tty: Simplify calling of put_pid. References: Date: Sun, 18 Mar 2007 13:03:08 -0600 In-Reply-To: (Eric W. Biederman's message of "Sun, 18 Mar 2007 12:57:27 -0600") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This patch should contain no functional changes. At somepoint I got confused and thought put_pid could not be called while a spin lock was held. While it may be nice to avoid that to reduce lock hold times put_pid can be safely called while we hold a spin lock. This patch removes all of the complications from the code introduced by my misunderstanding, making the code a little more readable. Signed-off-by: Eric W. Biederman --- drivers/char/tty_io.c | 23 ++++++----------------- 1 files changed, 6 insertions(+), 17 deletions(-) diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index 583730f..01fcfaf 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -155,8 +155,7 @@ int tty_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg); static int tty_fasync(int fd, struct file * filp, int on); static void release_tty(struct tty_struct *tty, int idx); -static struct pid *__proc_set_tty(struct task_struct *tsk, - struct tty_struct *tty); +static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty); /** * alloc_tty_struct - allocate a tty object @@ -1534,10 +1533,9 @@ void disassociate_ctty(int on_exit) } spin_lock_irq(¤t->sighand->siglock); - tty_pgrp = current->signal->tty_old_pgrp; + put_pid(current->signal->tty_old_pgrp); current->signal->tty_old_pgrp = NULL; spin_unlock_irq(¤t->sighand->siglock); - put_pid(tty_pgrp); mutex_lock(&tty_mutex); /* It is possible that do_tty_hangup has free'd this tty */ @@ -2508,7 +2506,6 @@ static int tty_open(struct inode * inode, struct file * filp) int index; dev_t device = inode->i_rdev; unsigned short saved_flags = filp->f_flags; - struct pid *old_pgrp; nonseekable_open(inode, filp); @@ -2602,17 +2599,15 @@ got_driver: goto retry_open; } - old_pgrp = NULL; mutex_lock(&tty_mutex); spin_lock_irq(¤t->sighand->siglock); if (!noctty && current->signal->leader && !current->signal->tty && tty->session == NULL) - old_pgrp = __proc_set_tty(current, tty); + __proc_set_tty(current, tty); spin_unlock_irq(¤t->sighand->siglock); mutex_unlock(&tty_mutex); - put_pid(old_pgrp); return 0; } @@ -3838,9 +3833,8 @@ void proc_clear_tty(struct task_struct *p) spin_unlock_irq(&p->sighand->siglock); } -static struct pid *__proc_set_tty(struct task_struct *tsk, struct tty_struct *tty) +static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty) { - struct pid *old_pgrp; if (tty) { /* We should not have a session or pgrp to here but.... */ put_pid(tty->session); @@ -3848,21 +3842,16 @@ static struct pid *__proc_set_tty(struct task_struct *tsk, struct tty_struct *tt tty->session = get_pid(task_session(tsk)); tty->pgrp = get_pid(task_pgrp(tsk)); } - old_pgrp = tsk->signal->tty_old_pgrp; + put_pid(tsk->signal->tty_old_pgrp); tsk->signal->tty = tty; tsk->signal->tty_old_pgrp = NULL; - return old_pgrp; } void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty) { - struct pid *old_pgrp; - spin_lock_irq(&tsk->sighand->siglock); - old_pgrp = __proc_set_tty(tsk, tty); + __proc_set_tty(tsk, tty); spin_unlock_irq(&tsk->sighand->siglock); - - put_pid(old_pgrp); } struct tty_struct *get_current_tty(void) -- 1.5.0.g53756