Re: [PATCH 3/9] IR: replace spinlock with mutex.

[Jarod Wilson <jarod@redhat.com>]

On Wed, Jul 28, 2010 at 07:32:58PM +0300, Maxim Levitsky wrote:
> On Wed, 2010-07-28 at 13:03 -0300, Mauro Carvalho Chehab wrote:
> > Em 28-07-2010 12:14, Maxim Levitsky escreveu:
> > > Some handlers (lirc for example) allocates memory on initialization,
> > > doing so in atomic context is cumbersome.
> > > Fixes warning about sleeping function in atomic context.
> > 
> > You should not replace it by a mutex, as the decoding code may happen during
> > IRQ time on several drivers.
> I though decoding code is run by a work queue?

Yeah, it is. (INIT_WORK(&ir->raw->rx_work, ir_raw_event_work); in
ir_raw_event_register).

> I don't see any atomic codepath here...

I think the ir_raw_event_store variants are the only things that are run
from an interrupt context, and none of them touch ir_raw_handler_lock.
That lock is advertised as being for the protection of ir_raw_handler_list
and ir_raw_client_list, which are primarily manipulated by
register/unregister functions, and we just lock them when doing actual IR
decode work (via said work queue) so we don't feed raw IR somewhere that
we shouldn't. I think Maxim is correct here, we should be okay with
changing this to a mutex, unless I'm missing something else.

-- 
Jarod Wilson
jarod@redhat.com