From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johan Hovold Subject: Re: [PATCH] serdev: Restore serdev_device_write_buf for atomic context Date: Mon, 8 May 2017 17:18:58 +0200 Message-ID: <20170508151858.GB30445@localhost> References: <1493380041-14710-1-git-send-email-stefan.wahren@i2se.com> <20170502090638.GB2973@localhost> <20170502131854.GA17710@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Rob Herring Cc: Stefan Wahren , Johan Hovold , Greg Kroah-Hartman , Jiri Slaby , Sebastian Reichel , Guenter Roeck , Andy Shevchenko , Andrey Smirnov , "linux-serial@vger.kernel.org" , "linux-kernel@vger.kernel.org" List-Id: linux-serial@vger.kernel.org On Thu, May 04, 2017 at 03:32:53PM -0500, Rob Herring wrote: > On Thu, May 4, 2017 at 11:22 AM, Stefan Wahren wrote: > > Am 02.05.2017 um 15:18 schrieb Johan Hovold: > >> On Tue, May 02, 2017 at 07:41:34AM -0500, Rob Herring wrote: > >>> On Tue, May 2, 2017 at 4:06 AM, Johan Hovold wrote: > >>>> On Fri, Apr 28, 2017 at 01:47:21PM +0200, Stefan Wahren wrote: > >>>>> Starting with commit 6fe729c4bdae ("serdev: Add serdev_device_write > >>>>> subroutine") the function serdev_device_write_buf cannot be used in > >>>>> atomic context anymore (mutex_lock is sleeping). So restore the old > >>>>> behavior. > >>>> Yeah, preventing use in atomic context seems unnecessary, although any > >>>> clients writing must now deal with serialisation themselves (as before, > >>>> and as they should). > >>> We could just remove the mutex for serdev_device_write and always make > >>> the client responsible for serialization. > >> That sounds reasonable. > > > > So it's unwanted to have 2 write functions (non-atomic, atomic)? > > No, it's unwanted to have more than we need. > > Looking closer, we'd also have to ensure the wait for completion is > not called also. So probably better to just leave it as you have done > it. Indeed. Sorry if my reply above was unclear on that point (i.e. that Stefan's patch is still needed regardless of whether we keep the mutex or not). Thanks, Johan