From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH 3/3] serial: 8250: Add a wakeup_capable module param Date: Fri, 20 Jan 2012 01:03:34 +0100 Message-ID: <201201200103.34296.rjw@sisk.pl> References: <1326826563-32215-1-git-send-email-sjg@chromium.org> <201201190102.58788.rjw@sisk.pl> <20120119013731.GK2431@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120119013731.GK2431@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: paulmck@linux.vnet.ibm.com Cc: Simon Glass , Alan Cox , LKML , Greg Kroah-Hartman , linux-serial@vger.kernel.org List-Id: linux-serial@vger.kernel.org On Thursday, January 19, 2012, Paul E. McKenney wrote: > On Thu, Jan 19, 2012 at 01:02:58AM +0100, Rafael J. Wysocki wrote: > > On Wednesday, January 18, 2012, Paul E. McKenney wrote: > > > On Wed, Jan 18, 2012 at 02:15:59PM -0800, Simon Glass wrote: [...] > > Yes, you can, but then I'd say it's not necessary for user space to > > be able to carry that out in a tight loop. So, it seems, alternatively, > > we could make that loop a bit less tight, e.g. by adding an arbitrary > > sleep to the user space interface for the "disable" case. > > Good point, that would work just as well and be simpler. Thanks for the confirmation! :-) By the way, I wonder, would it help to add synchronize_rcu() to wakeup_source_add() too? Then, even if device_wakeup_enable() and device_wakeup_disable() are executed in a tight loop for the same device, the list_add/list_del operations will always happen in different RCU cycles (or at least it seems so). Thanks, Rafael