Re: [PATCH] Bluetooth: Change chan_ready param from sk to chan

Hi Ulisses,

On Thu, Jan 26, 2012 at 01:04:06AM -0200, Ulisses Furquim wrote:

quoted

From: Andrei Emeltchenko <redacted>

Change is needed to remove dependency on sk when possible
before introducing l2cap channel lock.

What's the overall idea? We used to rely on sk lock for mutual
exclusion, right? (please correct me if I'm wrong) I'm seeing some
patches from you to change from sk to chan but introducing another
lock might shake things a bit so that's why I'm asking for the big
picture, if you have thought this through already.

Basically it is known that current implementation of some higher level
protocols like RFCOMM using kernel sockets is not the right way and shall
be changed at some point.

I've implemented basic A2MP protocol as a kernel socket and Marcel gave me
suggestion to move from sockets to internal L2CAP functions.

I've done this and since everything is locked with sk and obviously we do
not have socket I have to use following constructions:

<------8<-------------------
|  if (sk)
|          lock_sock(sk)
|  ...
|  if(sk)
|          release_sock(sk)
|
<------8<-------------------

which does not look nice and might be racy. Then comes idea to change
socket lock for L2CAP protocol to e.g. l2cap_channel_{lock,unlock}.

I have code which works but some parts looks like hacks so I try to polish
it a bit and send as RFC. Please give me comments if you think this might
be done other way.

Best regards 
Andrei Emeltchenko