Re: [PATCH v4 1/2] Bluetooth: Remove usage of __cancel_delayed_work()

Hi,

quoted

__cancel_delayed_work() is being used in some paths where we cannot
sleep waiting for the delayed work to finish. However, that function
might return while the timer is running and the work will be queued
again. Replace the calls with safer cancel_delayed_work() version
which spins until the timer handler finishes on other CPUs and
cancels the delayed work.

Signed-off-by: Ulisses Furquim <redacted>
---
 include/net/bluetooth/l2cap.h |    4 ++--
 net/bluetooth/l2cap_core.c    |    6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index e7a8cc7..42fdbb8 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h

@@ -614,7 +614,7 @@ static inline void l2cap_set_timer(struct l2cap_chan *chan,
 {
 	BT_DBG("chan %p state %d timeout %ld", chan, chan->state, timeout);
 
-	if (!__cancel_delayed_work(work))
+	if (!cancel_delayed_work(work))
 		l2cap_chan_hold(chan);
 	schedule_delayed_work(work, timeout);
 }

@@ -624,7 +624,7 @@ static inline bool l2cap_clear_timer(struct l2cap_chan *chan,
 {
 	bool ret;
 
-	ret = __cancel_delayed_work(work);
+	ret = cancel_delayed_work(work);
 	if (ret)
 		l2cap_chan_put(chan);
 

I have some questions about delayed_work usage:

When setting timer with l2cap_set_timer() we hold_chan if work may be
running. So if previous work is cancelled OK we do not hold chan.

Didn't we miss hold_chan here?

Then in l2cap_clear_chan we put_chan if work cancelled OK, otherwise
put_chan is done in delayed_work so we always put_chan.

What about following change:

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index a357336..d61e158 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h

@@ -628,17 +628,6 @@ static inline void l2cap_chan_unlock(struct

l2cap_chan *chan)
        mutex_unlock(&chan->lock);
 }
 
-static inline void l2cap_set_timer(struct l2cap_chan *chan,
-                                       struct delayed_work *work, long
                                        timeout)
-{
-       BT_DBG("chan %p state %s timeout %ld", chan,
-                                       state_to_string(chan->state),
                                        timeout);
-
-       if (!cancel_delayed_work(work))
-               l2cap_chan_hold(chan);
-       schedule_delayed_work(work, timeout);
-}
-
 static inline bool l2cap_clear_timer(struct l2cap_chan *chan,
                                        struct delayed_work *work)
 {

@@ -651,6 +640,18 @@ static inline bool l2cap_clear_timer(struct

l2cap_chan *chan,
        return ret;
 }
 
+static inline void l2cap_set_timer(struct l2cap_chan *chan,
+                                       struct delayed_work *work, long
timeout)
+{
+       BT_DBG("chan %p state %s timeout %ld", chan,
+                                       state_to_string(chan->state),
timeout);
+
+       l2cap_clear_timer(chan, work);
+
+       l2cap_chan_hold(chan);
+       schedule_delayed_work(work, timeout);
+}
+
 #define __set_chan_timer(c, t) l2cap_set_timer(c, &c->chan_timer, (t))
 #define __clear_chan_timer(c) l2cap_clear_timer(c, &c->chan_timer)
 #define __set_retrans_timer(c) l2cap_set_timer(c, &c->retrans_timer, \

Best regards 
Andrei Emeltchenko