Re: [PATCH v4 2/3] Bluetooth: cmtp: fix possible might sleep error in cmtp_session
From: AL Yu-Chen Cho <hidden>
Date: 2017-06-12 08:44:18
Also in:
linux-bluetooth, lkml
On Tue, 2017-02-14 at 08:55 +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 <redacted>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Remove unnecessary memory barrier before wake_up_* functions.Reviewed-by: AL Yu-Chen Cho <redacted>
quoted hunk ↗ jump to hunk
--- Changes in v3: Add brian's Reviewed-by. Changes in v2: None net/bluetooth/cmtp/core.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-)diff --git a/net/bluetooth/cmtp/core.c b/net/bluetooth/cmtp/core.c index 9e59b66..1152ce3 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 +392,7 @@ 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); + wake_up_interruptible(sk_sleep(session-quoted
sock->sk));up_write(&cmtp_session_sem); return err; }@@ -431,7 +430,11 @@ 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(); + + wake_up_interruptible(sk_sleep(session->sock->sk)); } else err = -ENOENT;