diff options
| author | NeilBrown | 2005-04-16 15:26:41 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2005-04-16 15:26:41 -0700 |
| commit | d28446fe2d87ea344c14741c39962dcc7aee5c78 (patch) | |
| tree | b41bec77e5e5123f8f5349eb01ced9ee8fd9a924 | |
| parent | 187a27845a9dc1c3da3995e24625ccf2e7a346aa (diff) | |
[PATCH] md: close a small race in md thread deregistration
There is a tiny race when de-registering an MD thread, in that the thread
could disappear before it is set a SIGKILL, causing send_sig to have
problems.
This is most easily closed by holding tasklist_lock between enabling the
thread to exit (setting ->run to NULL) and telling it to exit.
(akpm: ick. Needs to use kthread API and stop using signals)
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | drivers/md/md.c | 20 |
1 files changed, 8 insertions, 12 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index aa72c88a024f..44a164965546 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -2840,16 +2840,6 @@ mdk_thread_t *md_register_thread(void (*run) (mddev_t *), mddev_t *mddev, return thread; } -static void md_interrupt_thread(mdk_thread_t *thread) -{ - if (!thread->tsk) { - MD_BUG(); - return; - } - dprintk("interrupting MD-thread pid %d\n", thread->tsk->pid); - send_sig(SIGKILL, thread->tsk, 1); -} - void md_unregister_thread(mdk_thread_t *thread) { struct completion event; @@ -2857,9 +2847,15 @@ void md_unregister_thread(mdk_thread_t *thread) init_completion(&event); thread->event = &event; + + /* As soon as ->run is set to NULL, the task could disappear, + * so we need to hold tasklist_lock until we have sent the signal + */ + dprintk("interrupting MD-thread pid %d\n", thread->tsk->pid); + read_lock(&tasklist_lock); thread->run = NULL; - thread->name = NULL; - md_interrupt_thread(thread); + send_sig(SIGKILL, thread->tsk, 1); + read_unlock(&tasklist_lock); wait_for_completion(&event); kfree(thread); } |