From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753318AbaKGUOr (ORCPT ); Fri, 7 Nov 2014 15:14:47 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45910 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752462AbaKGUOp (ORCPT ); Fri, 7 Nov 2014 15:14:45 -0500 Date: Fri, 7 Nov 2014 21:14:54 +0100 From: Oleg Nesterov To: Andrew Morton Cc: Aaron Tomlin , Alexey Dobriyan , "Eric W. Biederman" , Sterling Alexander , linux-kernel@vger.kernel.org Subject: [PATCH 4/4] proc: task_state: ptrace_parent() doesn't need pid_alive() check Message-ID: <20141107201454.GA22246@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141107201424.GA22209@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 p->ptrace != 0 means that release_task(p) was not called, so pid_alive() buys nothing and we can remove this check. Other callers already use it directly without additional checks. Note: with or without this patch ptrace_parent() can return the pointer to the freed task, this will be explained/fixed later. Signed-off-by: Oleg Nesterov --- fs/proc/array.c | 13 ++++++------- 1 files changed, 6 insertions(+), 7 deletions(-) diff --git a/fs/proc/array.c b/fs/proc/array.c index 800e30f..bd117d0 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -157,19 +157,18 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, struct user_namespace *user_ns = seq_user_ns(m); struct group_info *group_info; int g; + struct task_struct *tracer; const struct cred *cred; - pid_t ppid, tpid, tgid, ngid; + pid_t ppid, tpid = 0, tgid, ngid; unsigned int max_fds = 0; rcu_read_lock(); ppid = pid_alive(p) ? task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0; - tpid = 0; - if (pid_alive(p)) { - struct task_struct *tracer = ptrace_parent(p); - if (tracer) - tpid = task_pid_nr_ns(tracer, ns); - } + + tracer = ptrace_parent(p); + if (tracer) + tpid = task_pid_nr_ns(tracer, ns); tgid = task_tgid_nr_ns(p, ns); ngid = task_numa_group_id(p); -- 1.5.5.1