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| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2010-03-05 13:42:56 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-03-06 11:26:33 -0800 |
| commit | 9728e5d6e6c432ee8487c63ce6e479e2474d9945 (patch) | |
| tree | 2cd7e9a9102649a36d52cbac918f045dcfaa08f2 /kernel/pid.c | |
| parent | 8aeee85a29e27e043db582bf2ae8e5f42767934f (diff) | |
| download | lwn-9728e5d6e6c432ee8487c63ce6e479e2474d9945.tar.gz lwn-9728e5d6e6c432ee8487c63ce6e479e2474d9945.zip | |
kernel/pid.c: update comment on find_task_by_pid_ns
tasklist_lock does protect the task and its pid, it can't go away. The
problem is that find_pid_ns() itself is unsafe without rcu lock, it can
race with copy_process()->free_pid(any_pid).
Protecting copy_process()->free_pid(any_pid) with tasklist_lock would make
it possible to call find_task_by_pid_ns() under tasklist safely, but we
don't do so because we are trying to get rid of the read_lock sites of
tasklist_lock.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/pid.c')
| -rw-r--r-- | kernel/pid.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/pid.c b/kernel/pid.c index b08e697cd83f..86b296943e5f 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -376,7 +376,7 @@ struct task_struct *pid_task(struct pid *pid, enum pid_type type) EXPORT_SYMBOL(pid_task); /* - * Must be called under rcu_read_lock() or with tasklist_lock read-held. + * Must be called under rcu_read_lock(). */ struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns) { |