Hi brian,
On 02/11/2017 09:40 AM, Brian Norris wrote:
Hi,
On Tue, Jan 24, 2017 at 12:07:49PM +0800, Jeffy Chen wrote:
It looks like bnep_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/bnep/core.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/net/bluetooth/bnep/core.c b/net/bluetooth/bnep/core.c
index fbf251f..da04d51 100644
--- a/net/bluetooth/bnep/core.c
+++ b/net/bluetooth/bnep/core.c
@@ -484,16 +484,16 @@ static int bnep_session(void *arg)
struct net_device *dev = s->dev;
struct sock *sk = s->sock->sk;
struct sk_buff *skb;
- wait_queue_t wait;
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
BT_DBG("");
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(&s->terminate))
break;
@@ -515,9 +515,8 @@ static int bnep_session(void *arg)
break;
netif_wake_queue(dev);
- schedule();
+ wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
}
- __set_current_state(TASK_RUNNING);
remove_wait_queue(sk_sleep(sk), &wait);
/* Cleanup session */
@@ -666,7 +665,11 @@ int bnep_del_connection(struct bnep_conndel_req *req)
s = __bnep_get_session(req->dst);
if (s) {
atomic_inc(&s->terminate);
- wake_up_process(s->task);
+
+ /* Ensure session->terminate is updated */
+ smp_mb__after_atomic();
+
__wake_up() suggests:
* It may be assumed that this function implies a write memory barrier before
* changing the task state if and only if any tasks are woken up.
so the above barrier is probably unnecessary. I'm not so sure about the
one before atomic_read(); seems fine.
Got it, thanx!
Other than that, I this looks ok:
Reviewed-by: Brian Norris <briannorris@xxxxxxxxxxx>
But I haven't been testing BNEP.
Brian
+ wake_up_interruptible(sk_sleep(s->sock->sk));
} else
err = -ENOENT;
--
2.1.4
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