From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9F23C4CEC4 for ; Wed, 18 Sep 2019 09:59:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AAB89218AF for ; Wed, 18 Sep 2019 09:59:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729125AbfIRJ7f (ORCPT ); Wed, 18 Sep 2019 05:59:35 -0400 Received: from relay1-d.mail.gandi.net ([217.70.183.193]:48367 "EHLO relay1-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725866AbfIRJ7e (ORCPT ); Wed, 18 Sep 2019 05:59:34 -0400 X-Originating-IP: 86.207.98.53 Received: from localhost (aclermont-ferrand-651-1-259-53.w86-207.abo.wanadoo.fr [86.207.98.53]) (Authenticated sender: gregory.clement@bootlin.com) by relay1-d.mail.gandi.net (Postfix) with ESMTPSA id 1A7AE240013; Wed, 18 Sep 2019 09:59:26 +0000 (UTC) From: Gregory CLEMENT To: Alexandre Belloni Cc: Codrin Ciubotariu , Liam Girdwood , Mark Brown , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, Nicolas Ferre , Ludovic Desroches , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] ASoC: atmel_ssc_dai: Remove wrong spinlock usage In-Reply-To: <20190918094800.GJ21254@piout.net> References: <20190918094114.15867-1-gregory.clement@bootlin.com> <20190918094800.GJ21254@piout.net> Date: Wed, 18 Sep 2019 11:59:25 +0200 Message-ID: <87impq7wn6.fsf@FE-laptop> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Alex, > On 18/09/2019 11:41:14+0200, Gregory CLEMENT wrote: >> A potential bug was reported in the email "[BUG] atmel_ssc_dai: a >> possible sleep-in-atomic bug in atmel_ssc_shutdown"[1] >> >> Indeed in the function atmel_ssc_shutdown() free_irq() was called in a >> critical section protected by spinlock. >> >> However this spinlock is only used in atmel_ssc_shutdown() and >> atmel_ssc_startup() functions. After further analysis, it occurred that >> the call to these function are already protected by mutex used on the >> calling functions. >> >> Then we can remove the spinlock which will fix this bug as a side >> effect. Thanks to this patch the following message disappears: >> >> "BUG: sleeping function called from invalid context at >> kernel/locking/mutex.c:909" >> >> [1]: https://www.spinics.net/lists/alsa-devel/msg71286.html >> >> Signed-off-by: Gregory CLEMENT >> --- >> sound/soc/atmel/atmel_ssc_dai.c | 7 ------- >> 1 file changed, 7 deletions(-) >> >> diff --git a/sound/soc/atmel/atmel_ssc_dai.c b/sound/soc/atmel/atmel_ssc_dai.c >> index 6f89483ac88c..365957e86419 100644 >> --- a/sound/soc/atmel/atmel_ssc_dai.c >> +++ b/sound/soc/atmel/atmel_ssc_dai.c >> @@ -116,19 +116,16 @@ static struct atmel_pcm_dma_params ssc_dma_params[NUM_SSC_DEVICES][2] = { >> static struct atmel_ssc_info ssc_info[NUM_SSC_DEVICES] = { >> { >> .name = "ssc0", >> - .lock = __SPIN_LOCK_UNLOCKED(ssc_info[0].lock), > > This member is now unused and can be removed from the struct. > > Once fixed, Reviewed-by: Alexandre Belloni > Indeed I wanted to do this but finally forgot. I am sending a v2. Thanks, Gregory > >> .dir_mask = SSC_DIR_MASK_UNUSED, >> .initialized = 0, >> }, >> { >> .name = "ssc1", >> - .lock = __SPIN_LOCK_UNLOCKED(ssc_info[1].lock), >> .dir_mask = SSC_DIR_MASK_UNUSED, >> .initialized = 0, >> }, >> { >> .name = "ssc2", >> - .lock = __SPIN_LOCK_UNLOCKED(ssc_info[2].lock), >> .dir_mask = SSC_DIR_MASK_UNUSED, >> .initialized = 0, >> }, >> @@ -317,13 +314,11 @@ static int atmel_ssc_startup(struct snd_pcm_substream *substream, >> >> snd_soc_dai_set_dma_data(dai, substream, dma_params); >> >> - spin_lock_irq(&ssc_p->lock); >> if (ssc_p->dir_mask & dir_mask) { >> spin_unlock_irq(&ssc_p->lock); >> return -EBUSY; >> } >> ssc_p->dir_mask |= dir_mask; >> - spin_unlock_irq(&ssc_p->lock); >> >> return 0; >> } >> @@ -355,7 +350,6 @@ static void atmel_ssc_shutdown(struct snd_pcm_substream *substream, >> >> dir_mask = 1 << dir; >> >> - spin_lock_irq(&ssc_p->lock); >> ssc_p->dir_mask &= ~dir_mask; >> if (!ssc_p->dir_mask) { >> if (ssc_p->initialized) { >> @@ -369,7 +363,6 @@ static void atmel_ssc_shutdown(struct snd_pcm_substream *substream, >> ssc_p->cmr_div = ssc_p->tcmr_period = ssc_p->rcmr_period = 0; >> ssc_p->forced_divider = 0; >> } >> - spin_unlock_irq(&ssc_p->lock); >> >> /* Shutdown the SSC clock. */ >> pr_debug("atmel_ssc_dai: Stopping clock\n"); >> -- >> 2.23.0 >> > > -- > Alexandre Belloni, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com -- Gregory Clement, Bootlin Embedded Linux and Kernel engineering http://bootlin.com