2005-11-09 03:22:28

by Paul E. McKenney

Subject: [PATCH] tasklist-RCU fix in attach_pid()

Hello!

Bug in attach_pid() can result in RCU readers in find_pid() getting
confused if they race with process creation.

Signed-off-by: <[email protected]>

---

(applies to both 2.6.14-mm1 and -rt)

pid.c | 2 +-
1 files changed, 1 insertion(+), 1 deletion(-)

diff -uprNa -X dontdiff linux-2.6.14-mm1/kernel/pid.c linux-2.6.14-mm1-fix-1/kernel/pid.c
--- linux-2.6.14-mm1/kernel/pid.c 2005-11-08 08:18:55.000000000 -0800
+++ linux-2.6.14-mm1-fix-1/kernel/pid.c 2005-11-08 19:02:35.000000000 -0800
@@ -150,6 +150,7 @@ int fastcall attach_pid(task_t *task, en

task_pid = &task->pids[type];
pid = find_pid(type, nr);
+ task_pid->nr = nr;
if (pid == NULL) {
INIT_LIST_HEAD(&task_pid->pid_list);
hlist_add_head_rcu(&task_pid->pid_chain,
@@ -158,7 +159,6 @@ int fastcall attach_pid(task_t *task, en
INIT_HLIST_NODE(&task_pid->pid_chain);
list_add_tail_rcu(&task_pid->pid_list, &pid->pid_list);
}
- task_pid->nr = nr;

return 0;
}

2005-11-09 08:15:58

by William Lee Irwin III

Subject: Re: [PATCH] tasklist-RCU fix in attach_pid()

On Tue, Nov 08, 2005 at 07:22:34PM -0800, Paul E. McKenney wrote:
> Bug in attach_pid() can result in RCU readers in find_pid() getting
> confused if they race with process creation.
> Signed-off-by: <[email protected]>

Simple enough.

Acked-by: William Irwin <[email protected]>


-- wli

2005-11-09 14:35:59

by Ingo Molnar

Subject: Re: [PATCH] tasklist-RCU fix in attach_pid()

* Paul E. McKenney <[email protected]> wrote:

> Hello!
>
> Bug in attach_pid() can result in RCU readers in find_pid() getting
> confused if they race with process creation.
>
> Signed-off-by: <[email protected]>

yeah ...

Acked-by: Ingo Molnar <[email protected]>

Ingo