Hi brian,
On 02/11/2017 09:43 AM, Brian Norris wrote:
Hi,
On Tue, Jan 24, 2017 at 12:07:50PM +0800, Jeffy Chen wrote:
It looks like cmtp_session 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@xxxxxxxxxxxxxx>
---
net/bluetooth/cmtp/core.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/net/bluetooth/cmtp/core.c b/net/bluetooth/cmtp/core.c
index 9e59b66..6b03f2b 100644
--- a/net/bluetooth/cmtp/core.c
+++ b/net/bluetooth/cmtp/core.c
@@ -280,16 +280,16 @@ static int cmtp_session(void *arg)
struct cmtp_session *session = arg;
struct sock *sk = session->sock->sk;
struct sk_buff *skb;
- wait_queue_t wait;
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
BT_DBG("session %p", session);
set_user_nice(current, -15);
- init_waitqueue_entry(&wait, current);
add_wait_queue(sk_sleep(sk), &wait);
while (1) {
- set_current_state(TASK_INTERRUPTIBLE);
+ /* Ensure session->terminate is updated */
+ smp_mb__before_atomic();
if (atomic_read(&session->terminate))
break;
@@ -306,9 +306,8 @@ static int cmtp_session(void *arg)
cmtp_process_transmit(session);
- schedule();
+ wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
}
- __set_current_state(TASK_RUNNING);
remove_wait_queue(sk_sleep(sk), &wait);
down_write(&cmtp_session_sem);
@@ -393,7 +392,11 @@ int cmtp_add_connection(struct cmtp_connadd_req *req, struct socket *sock)
err = cmtp_attach_device(session);
if (err < 0) {
atomic_inc(&session->terminate);
- wake_up_process(session->task);
+
+ /* Ensure session->terminate is updated */
+ smp_mb__after_atomic();
+
Same comment about the barrier.
Done, there are barriers in wake functions indeed, thanx!
+ wake_up_interruptible(sk_sleep(session->sock->sk));
up_write(&cmtp_session_sem);
return err;
}
@@ -431,7 +434,11 @@ int cmtp_del_connection(struct cmtp_conndel_req *req)
/* Stop session thread */
atomic_inc(&session->terminate);
- wake_up_process(session->task);
+
+ /* Ensure session->terminate is updated */
+ smp_mb__after_atomic();
And again.
But otherwise I think this looks OK, again with the caveat that I don't
know Bluetooth/CMTP that well:
Reviewed-by: Brian Norris <briannorris@xxxxxxxxxxxx>
+
+ wake_up_interruptible(sk_sleep(session->sock->sk));
} else
err = -ENOENT;
--
2.1.4
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