Hi Andrei,
> > > For receiving ACL packets use __l2cap_get_chan_by_scid which is not
> > > locking sk and explicitly lock sk after checking that it is exist.
> > > Code looks nicer since now it is surrounded by lock/release.
> > >
> > > Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@xxxxxxxxx>
> > > ---
> > > net/bluetooth/l2cap_core.c | 7 +++++--
> > > 1 files changed, 5 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> > > index d16ad49..53dbfd3 100644
> > > --- a/net/bluetooth/l2cap_core.c
> > > +++ b/net/bluetooth/l2cap_core.c
> > > @@ -4243,7 +4243,7 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk
> > > u16 tx_seq;
> > > int len;
> > >
> > > - chan = l2cap_get_chan_by_scid(conn, cid);
> > > + chan = __l2cap_get_chan_by_scid(conn, cid);
> > > if (!chan) {
> > > if (cid == L2CAP_CID_A2MP) {
> > > chan = a2mp_channel_create(conn, skb);
> > > @@ -4255,6 +4255,8 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk
> > > }
> > >
> > > sk = chan->sk;
> > > + if (sk)
> > > + lock_sock(sk);
> >
> > this is the part I clearly do not like. This is pretty nasty conditional
> > locking. We need to figure out something better.
>
> Actually l2cap_data_channel function ends with:
>
> <------8<--------------------
> | if (sk)
> | release_sock(sk);
> |
> <------8<--------------------
that one slipped past me :(
> So in _this_ case it looks consistent. But I agree that generally it does
> not looks nice. The reason for that is l2cap_chan is locked with socket
> lock. Maybe we could create mutex l2cap_lock and functions like
> lock_chan(chan) / unlock_chan(chan) and change socket locks in l2cap_core
> with these new locks?
I agree. Lets see what happens if we lock l2cap_chan with its own lock.
Regards
Marcel
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