Commit 5da8e47d authored by Jeffy Chen's avatar Jeffy Chen Committed by Marcel Holtmann
Browse files

Bluetooth: hidp: fix possible might sleep error in hidp_session_thread 

It looks like hidp_session_thread has same pattern as the issue reported in
old rfcomm:

	while (1) {
		set_current_state(TASK_INTERRUPTIBLE);
		if (condition)
			break;
		// may call might_sleep here
		schedule();
	}
	__set_current_state(TASK_RUNNING);

Which fixed at:
	dfb2fae7 Bluetooth: Fix nested sleeps

So let's fix it at the same way, also follow the suggestion of:
https://lwn.net/Articles/628628/



Signed-off-by: default avatarJeffy Chen <jeffy.chen@rock-chips.com>
Tested-by: default avatarAL Yu-Chen Cho <acho@suse.com>
Tested-by: default avatarRohit Vaswani <rvaswani@nvidia.com>
Signed-off-by: default avatarMarcel Holtmann <marcel@holtmann.org>
parent f06d9773

net/bluetooth/hidp/core.c

+22 −11
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ 
#define VERSION "1.2"



static DECLARE_RWSEM(hidp_session_sem);

static DECLARE_WAIT_QUEUE_HEAD(hidp_session_wq);

static LIST_HEAD(hidp_session_list);



static unsigned char hidp_keycode[256] = {
@@ -1068,12 +1069,12 @@ static int hidp_session_start_sync(struct hidp_session *session) 
 * Wake up session thread and notify it to stop. This is asynchronous and

 * returns immediately. Call this whenever a runtime error occurs and you want

 * the session to stop.

 * Note: wake_up_process() performs any necessary memory-barriers for us.

 * Note: wake_up_interruptible() performs any necessary memory-barriers for us.

 */

static void hidp_session_terminate(struct hidp_session *session)

{

	atomic_inc(&session->terminate);

	wake_up_process(session->task);

	wake_up_interruptible(&hidp_session_wq);

}



/*
@@ -1180,7 +1181,9 @@ static void hidp_session_run(struct hidp_session *session) 
	struct sock *ctrl_sk = session->ctrl_sock->sk;

	struct sock *intr_sk = session->intr_sock->sk;

	struct sk_buff *skb;

	DEFINE_WAIT_FUNC(wait, woken_wake_function);



	add_wait_queue(&hidp_session_wq, &wait);

	for (;;) {

		/*

		 * This thread can be woken up two ways:
@@ -1188,12 +1191,10 @@ static void hidp_session_run(struct hidp_session *session) 
		 *    session->terminate flag and wakes this thread up.

		 *  - Via modifying the socket state of ctrl/intr_sock. This

		 *    thread is woken up by ->sk_state_changed().

		 *

		 * Note: set_current_state() performs any necessary

		 * memory-barriers for us.

		 */

		set_current_state(TASK_INTERRUPTIBLE);



		/* Ensure session->terminate is updated */

		smp_mb__before_atomic();

		if (atomic_read(&session->terminate))

			break;
@@ -1227,11 +1228,22 @@ static void hidp_session_run(struct hidp_session *session) 
		hidp_process_transmit(session, &session->ctrl_transmit,

				      session->ctrl_sock);



		schedule();

		wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);

	}

	remove_wait_queue(&hidp_session_wq, &wait);



	atomic_inc(&session->terminate);

	set_current_state(TASK_RUNNING);



	/* Ensure session->terminate is updated */

	smp_mb__after_atomic();

}



static int hidp_session_wake_function(wait_queue_t *wait,

				      unsigned int mode,

				      int sync, void *key)

{

	wake_up_interruptible(&hidp_session_wq);

	return false;

}



/*
@@ -1244,7 +1256,8 @@ static void hidp_session_run(struct hidp_session *session) 
static int hidp_session_thread(void *arg)

{

	struct hidp_session *session = arg;

	wait_queue_t ctrl_wait, intr_wait;

	DEFINE_WAIT_FUNC(ctrl_wait, hidp_session_wake_function);

	DEFINE_WAIT_FUNC(intr_wait, hidp_session_wake_function);



	BT_DBG("session %p", session);
@@ -1254,8 +1267,6 @@ static int hidp_session_thread(void *arg) 
	set_user_nice(current, -15);

	hidp_set_timer(session);



	init_waitqueue_entry(&ctrl_wait, current);

	init_waitqueue_entry(&intr_wait, current);

	add_wait_queue(sk_sleep(session->ctrl_sock->sk), &ctrl_wait);

	add_wait_queue(sk_sleep(session->intr_sock->sk), &intr_wait);

	/* This memory barrier is paired with wq_has_sleeper(). See

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