From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754134AbaHETtz (ORCPT ); Tue, 5 Aug 2014 15:49:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51147 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754090AbaHETto (ORCPT ); Tue, 5 Aug 2014 15:49:44 -0400 Date: Tue, 5 Aug 2014 21:47:07 +0200 From: Oleg Nesterov To: Andrew Morton Cc: Alexander Viro , Cyrill Gorcunov , David Howells , "David S. Miller" , "Eric W. Biederman" , "Kirill A. Shutemov" , "Kirill A. Shutemov" , Peter Zijlstra , Sasha Levin , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 7/7] fs/proc/task_mmu.c: shift "priv->task = NULL" from m_start() to m_stop() Message-ID: <20140805194707.GA30746@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140805194627.GA30693@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 1. There is no reason to reset ->tail_vma in m_start(), if we return IS_ERR_OR_NULL() it won't be used. 2. m_start() also clears priv->task to ensure that m_stop() won't use the stale pointer if we fail before get_task_struct(). But this is ugly and confusing, move this initialization in m_stop(). Signed-off-by: Oleg Nesterov --- fs/proc/task_mmu.c | 9 +++------ 1 files changed, 3 insertions(+), 6 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index c4c8825..5f7fb45 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -145,17 +145,12 @@ static void *m_start(struct seq_file *m, loff_t *pos) struct vm_area_struct *vma, *tail_vma = NULL; loff_t l = *pos; - /* Clear the per syscall fields in priv */ - priv->task = NULL; - priv->tail_vma = NULL; - /* * We remember last_addr rather than next_addr to hit with * vmacache most of the time. We have zero last_addr at * the beginning and also after lseek. We will have -1 last_addr * after the end of the vmas. */ - if (last_addr == -1UL) return NULL; @@ -227,8 +222,10 @@ static void m_stop(struct seq_file *m, void *v) if (!IS_ERR_OR_NULL(v)) vma_stop(priv); - if (priv->task) + if (priv->task) { put_task_struct(priv->task); + priv->task = NULL; + } } static int proc_maps_open(struct inode *inode, struct file *file, -- 1.5.5.1