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authorNeilBrown <neilb@cse.unsw.edu.au>2005-04-16 15:26:41 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:26:41 -0700
commitd28446fe2d87ea344c14741c39962dcc7aee5c78 (patch)
treeb41bec77e5e5123f8f5349eb01ced9ee8fd9a924 /drivers/md/md.c
parent187a27845a9dc1c3da3995e24625ccf2e7a346aa (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>
Diffstat (limited to 'drivers/md/md.c')
-rw-r--r--drivers/md/md.c20
1 files changed, 8 insertions, 12 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c
index aa72c88a024..44a16496554 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);
}