Re: [RFCv0 1/5] Bluetooth: Use locks in RCU updater code

Hi Ulisses,

On Tue, Jan 31, 2012 at 10:37:38AM -0200, Ulisses Furquim wrote:

On Tue, Jan 31, 2012 at 5:59 AM, Emeltchenko Andrei
[off-list ref] wrote:

quoted

On Mon, Jan 30, 2012 at 03:17:15PM -0200, Ulisses Furquim wrote:

quoted

I was under the impression you'd remove RCU for conn->chan_l
completely. You're adding a lock only in the updaters? If so, please
take a look at commit 3d57dc680 which shows all changes from mutex to
RCU. I don't think just adding a lock/unlock in l2cap_conn_start and
l2cap_conn_del will be enough. l2cap_chan_add seems to be called from
other contexts and it does a list_add_rcu(). Have you thought of that?

I am adding lock to updaters and to the places we need to sleep and
rcu_read_lock cannot be used. This patch adds locks to updaters and
following patches cover other places. Maybe I need to split them better.

It needs to be split better, yes. And if you're adding a mutex also in
some readers of the list instead of using RCU I believe it'd be better
to just use a mutex and remove RCU usage altogether. That will be
possibly just a revert of 3d57dc6806, but you need to check that.

I actually do think that this will be better, in next patches I will
revert the commit mentioned.

Best regards 
Andrei Emeltchenko