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Bluetooth: bnep: Fix deadlock in session deletion

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Commit f4d7cd4a4c introduced the usage of kthread API.
kthread_stop is a blocking function which returns only when
the thread exits. In this case, the thread can't exit because it's
waiting for the write lock, which is being held by bnep_del_connection()
which is waiting for the thread to exit -- deadlock.

Use atomic_t/wake_up_process instead to signal to the thread to exit.

Change-Id: I538cd17c102cb31b3212c794086a9c2baedb4b14
Signed-off-by: Jaikumar Ganesh <jaikumar@google.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
[skrovvid@codeaurora.org: kthread_should_stop api call is avoided]
Signed-off-by: Srinivas Krovvidi <skrovvid@codeaurora.org>
This commit is contained in:
Peter Hurley
2011-08-05 10:41:35 -04:00
committed by Srinivas Krovvidi
parent e8992f2213
commit 2db3637b45
2 changed files with 8 additions and 4 deletions
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1
net/bluetooth/bnep/bnep.h
View File

@@ -155,6 +155,7 @@ struct bnep_session {
unsigned int role; unsigned int role;
unsigned long state; unsigned long state;
unsigned long flags; unsigned long flags;
atomic_t terminate;
struct task_struct *task; struct task_struct *task;
struct ethhdr eh; struct ethhdr eh;

11
net/bluetooth/bnep/core.c
View File

@@ -484,9 +484,11 @@ static int bnep_session(void *arg)
init_waitqueue_entry(&wait, current); init_waitqueue_entry(&wait, current);
add_wait_queue(sk_sleep(sk), &wait); add_wait_queue(sk_sleep(sk), &wait);
while (!kthread_should_stop()) { while (1) {
set_current_state(TASK_INTERRUPTIBLE); set_current_state(TASK_INTERRUPTIBLE);
if (atomic_read(&s->terminate))
break;
/* RX */ /* RX */
while ((skb = skb_dequeue(&sk->sk_receive_queue))) { while ((skb = skb_dequeue(&sk->sk_receive_queue))) {
skb_orphan(skb); skb_orphan(skb);
@@ -643,9 +645,10 @@ int bnep_del_connection(struct bnep_conndel_req *req)
down_read(&bnep_session_sem); down_read(&bnep_session_sem);
s = __bnep_get_session(req->dst); s = __bnep_get_session(req->dst);
if (s) if (s) {
kthread_stop(s->task); atomic_inc(&s->terminate);
else wake_up_process(s->task);
} else
err = -ENOENT; err = -ENOENT;
up_read(&bnep_session_sem); up_read(&bnep_session_sem);