[PATCH 4.12 81/99] Bluetooth: hidp: fix possible might sleep error in hidp_session_thread

Greg Kroah-Hartman
2017-08-28T08:10:21Z

From: Jeffy Chen <jeffy.chen@rock-chips.com>

commit 5da8e47d849d3d37b14129f038782a095b9ad049 upstream.

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:
dfb2fae 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: Jeffy Chen <jeffy.chen@rock-chips.com>
Tested-by: AL Yu-Chen Cho <acho@suse.com>
Tested-by: Rohit Vaswani <rvaswani@nvidia.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/bluetooth/hidp/core.c | 33 ++++++++++++++++++++++-----------
1 file changed, 22 insertions(+), 11 deletions(-)

--- a/net/bluetooth/hidp/core.c
+++ b/net/bluetooth/hidp/core.c
@@ -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(struc
* 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
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->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
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
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