Re: [RESEND PATCH v4 1/3] Bluetooth: bnep: fix possible might sleep error in bnep_session

[Marcel Holtmann]

Hi Jeffy,

> 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 
> Reviewed-by: Brian Norris 
> Reviewed-by: AL Yu-Chen Cho 
> ---
> 
> Changes in v4: None
> Changes in v2: None
> 
> net/bluetooth/bnep/core.c | 11 +--
> 1 file changed, 5 insertions(+), 6 deletions(-)

all 3 patches have been applied to bluetooth-next tree.

Regards

Marcel

[RESEND PATCH v4 1/3] Bluetooth: bnep: fix possible might sleep error in bnep_session

[Jeffy Chen]

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 
Reviewed-by: Brian Norris 
Reviewed-by: AL Yu-Chen Cho 
---

Changes in v4: None
Changes in v2: None

 net/bluetooth/bnep/core.c | 11 +--
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/net/bluetooth/bnep/core.c b/net/bluetooth/bnep/core.c
index fbf251f..4d6b94d 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(, current);
add_wait_queue(sk_sleep(sk), );
while (1) {
-   set_current_state(TASK_INTERRUPTIBLE);
+   /* Ensure session->terminate is updated */
+   smp_mb__before_atomic();
 
if (atomic_read(>terminate))
break;
@@ -515,9 +515,8 @@ static int bnep_session(void *arg)
break;
netif_wake_queue(dev);
 
-   schedule();
+   wait_woken(, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
}
-   __set_current_state(TASK_RUNNING);
remove_wait_queue(sk_sleep(sk), );
 
/* Cleanup session */
@@ -666,7 +665,7 @@ int bnep_del_connection(struct bnep_conndel_req *req)
s = __bnep_get_session(req->dst);
if (s) {
atomic_inc(>terminate);
-   wake_up_process(s->task);
+   wake_up_interruptible(sk_sleep(s->sock->sk));
} else
err = -ENOENT;
 
-- 
2.1.4