Subject: [PATCH 5/6] Use task_pid() to find leader's pid

From: Sukadev Bhattiprolu <sukadev@us.ibm.com>

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 <sukadev@us.ibm.com>
---
 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	2007-07-05 18:56:53.000000000 -0700
+++ lx26-22-rc6-mm1/fs/exec.c	2007-07-05 18:58:32.000000000 -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);
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sukadev@us.ibm.com wrote:
> Subject: [PATCH 5/6] Use task_pid() to find leader's pid
> 
> From: Sukadev Bhattiprolu <sukadev@us.ibm.com>
> 
> 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 <sukadev@us.ibm.com>

Acked-by: Pavel Emelianov <xemul@openvz.org>

> ---
>  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	2007-07-05 18:56:53.000000000 -0700
> +++ lx26-22-rc6-mm1/fs/exec.c	2007-07-05 18:58:32.000000000 -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);
> _______________________________________________
> Containers mailing list
> Containers@lists.linux-foundation.org
> https://lists.linux-foundation.org/mailman/listinfo/containers
> 
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