Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751547AbdFFQro (ORCPT ); Tue, 6 Jun 2017 12:47:44 -0400 Received: from mx2.suse.de ([195.135.220.15]:40920 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751200AbdFFQrm (ORCPT ); Tue, 6 Jun 2017 12:47:42 -0400 Date: Tue, 6 Jun 2017 18:47:34 +0200 From: "Luis R. Rodriguez" To: Alan Cox , fsdevel@vger.kernel.org, Stephen Boyd , "Li, Yi" Cc: "Luis R. Rodriguez" , Dmitry Torokhov , Peter Zijlstra , Jonathan Corbet , "Eric W. Biederman" , "Michael Kerrisk (man-pages)" , Andy Lutomirski , Greg KH , "Fuzzey, Martin" , Linux API , Daniel Wagner , David Woodhouse , jewalt@lgsinnovations.com, rafal@milecki.pl, Arend Van Spriel , "Rafael J. Wysocki" , atull@opensource.altera.com, Moritz Fischer , Petr Mladek , Johannes Berg , Emmanuel Grumbach , Luca Coelho , Kalle Valo , Linus Torvalds , Kees Cook , AKASHI Takahiro , David Howells , Peter Jones , Hans de G oede , "Ted Ts'o" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v2] firmware: fix sending -ERESTARTSYS due to signal on fallback Message-ID: <20170606164734.GB27288@wotan.suse.de> References: <87fufr3mdy.fsf@xmission.com> <20170526194640.GS8951@wotan.suse.de> <20170526215518.GB40877@dtor-ws> <20170605202410.GQ8951@wotan.suse.de> <1496760796.5682.48.camel@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1496760796.5682.48.camel@linux.intel.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1791 Lines: 50 Adding fsdevel folks. On Tue, Jun 06, 2017 at 03:53:16PM +0100, Alan Cox wrote: > > "Unix tradition (and thus almost all applications) believe file store > > writes to > > be non signal interruptible. It would not be safe or practical to > > change that > > guarantee." > > Yep everyone codes > > write(disk_file, "foo", 3); > > not while(..) blah around it. Thanks for the confirmation! That's a simple enough explanation. > > For these two reasons then it would seem best we do two things > > actually: > > > > 1) return -EINTR instead of -EAGAIN when we detect > > swait_event_interruptible_timeout() > > got interrupted by a signal (it returns -ERESTARTSYS) > > 2) Do as you note below and add wait_event_killable_timeout() > > Pedantic detail that I don't think affects you > > If you have completed a part of the I/O then you should return the byte > processed count not EINTR, but -1,EINTR if no progress was made. You are right with some new exceptions and with regards to the future: The syfs loading interface for firmware currently goes through the data file exposed on syfs, the respective write op firmware_data_write() only checks for signals at the beginning. After that its a full one swoop try to write if you are following the old tradition and are using a buffer allocated by the firmware API. If you are using the relatively new request_firmware_into_buf() added by Stephen Boyd which lets the driver provide the allocated buffer then we have a loop in firmware_rw() which should be fixed to: 1) Check for signals 2) Do what you noted above. Furthermore Yi Li over at Intel is adding some new API calls which would re-use some of this for FPGA firmwares which are also very large, that work should consider the above and fix appropriately as well. Luis