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Commit 751c10a5 authored by Peter Hurley's avatar Peter Hurley Committed by Gustavo Padovan
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Bluetooth: bnep: Fix deadlock in session deletion 



Commit f4d7cd4a 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.

Signed-off-by: default avatarJaikumar Ganesh <jaikumar@google.com>
Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGustavo F. Padovan <padovan@profusion.mobi>
parent 7bdb8a5c

net/bluetooth/bnep/bnep.h

+1 −0
Original line number Diff line number Diff line
@@ -155,6 +155,7 @@ struct bnep_session { 
	unsigned int  role;

	unsigned long state;

	unsigned long flags;

	atomic_t      terminate;

	struct task_struct *task;



	struct ethhdr eh;

net/bluetooth/bnep/core.c

+5 −4
Original line number Diff line number Diff line
@@ -487,7 +487,7 @@ static int bnep_session(void *arg) 
	while (1) {

		set_current_state(TASK_INTERRUPTIBLE);



		if (kthread_should_stop())

		if (atomic_read(&s->terminate))

			break;

		/* RX */

		while ((skb = skb_dequeue(&sk->sk_receive_queue))) {
@@ -642,9 +642,10 @@ int bnep_del_connection(struct bnep_conndel_req *req) 
	down_read(&bnep_session_sem);



	s = __bnep_get_session(req->dst);

	if (s)

		kthread_stop(s->task);

	else

	if (s) {

		atomic_inc(&s->terminate);

		wake_up_process(s->task);

	} else

		err = -ENOENT;



	up_read(&bnep_session_sem);