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tasklist-RCU fix in attach_pid()

PATCH In review Paul E. McKenney 3 participants 3 messages Nov 9, 2005

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Paul E. McKenney

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PATCH 1/1 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(-)
kernel/pid.c +1 -1
diff -uprNa -X dontdiff linux-2.6.14-mm1/kernel/pid.c linux-2.6.14-mm1-fix-1/kernel/pid.c
@@ -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;
 }