From mboxrd@z Thu Jan 1 00:00:00 1970 From: sukadev@us.ibm.com Subject: [PATCH 3/5] Use task_pid() to find leader's pid Date: Sat, 14 Jul 2007 21:57:30 -0700 Message-ID: <20070715045730.GD25053@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: Andrew Morton , linux-kernel@vger.kernel.org Cc: Pavel Emelianov , serue@us.ibm.com, clg@fr.ibm.com, haveblue@us.ibm.com, Containers List-Id: containers.vger.kernel.org Subject: [PATCH 3/5] Use task_pid() to find leader's pid From: Sukadev Bhattiprolu Use task_pid() to get leader's pid since find_pid() cannot be used after detach_pid(). See comments in the code below for more details. Signed-off-by: Sukadev Bhattiprolu Acked-by: Pavel Emelianov Cc: Eric W. Biederman Cc: Cedric Le Goater Cc: Dave Hansen Cc: Serge Hallyn Cc: Herbert Poetzel --- fs/exec.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) Index: lx26-22-rc6-mm1/fs/exec.c =================================================================== --- lx26-22-rc6-mm1.orig/fs/exec.c 2007-07-13 13:12:01.000000000 -0700 +++ lx26-22-rc6-mm1/fs/exec.c 2007-07-13 13:12:13.000000000 -0700 @@ -905,10 +905,17 @@ static int de_thread(struct task_struct * The old leader becomes a thread of the this thread group. * Note: The old leader also uses this pid until release_task * is called. Odd but simple and correct. + * Note: With multiple pid namespaces, active pid namespace of + * a process is stored in its struct pid. The detach_pid + * below frees the struct pid, so we will have no notion + * of an active pid namespace until we complete the + * subsequent attach_pid(). Which means - calls like + * find_pid()/pid_to_nr() return NULL and cannot be used + * between the detach_pid() and attach_pid() calls. */ detach_pid(tsk, PIDTYPE_PID); tsk->pid = leader->pid; - attach_pid(tsk, PIDTYPE_PID, find_pid(tsk->pid)); + attach_pid(tsk, PIDTYPE_PID, task_pid(leader)); transfer_pid(leader, tsk, PIDTYPE_PGID); transfer_pid(leader, tsk, PIDTYPE_SID); list_replace_rcu(&leader->tasks, &tsk->tasks);