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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 5B853C63699 for ; Wed, 28 Oct 2020 22:12:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 19CBE20809 for ; Wed, 28 Oct 2020 22:12:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603923156; bh=Uig8XlVVywuZSs/xiHVDxKfmc2EvUkGvRLURSxmRfOM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=dojBQ0+aLOuyLCRApKxJUqjDUeBra3j269RUiyi+dmfNTKXJGOjaBZLr8IXb/FA/F nfOiPP8Wfrh5Wb6XUglNVQhe96Y+mvROEhssZ4RzGEy9rqm8ppYLadYeqwR7Pr/jdC u688jFJTovDOe9oSVPL8/yGolU9P3LmfmYrFdkwE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730850AbgJ1WMc (ORCPT ); Wed, 28 Oct 2020 18:12:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:56480 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730832AbgJ1WMY (ORCPT ); Wed, 28 Oct 2020 18:12:24 -0400 Received: from google.com (unknown [104.132.1.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E2A9E24795; Wed, 28 Oct 2020 19:43:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603914234; bh=Uig8XlVVywuZSs/xiHVDxKfmc2EvUkGvRLURSxmRfOM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dfusWPKWqTKRnMdbvN3oZ846WjjPGP1zahpiGLPq7lLhrOPyDeFDLz1cHc9PWFcZx AfCnIMUYVw2KHtvQTMXiA8EyfosDwA6yEnKTaOfqCqREvHybxFLydVlbuyxPljCaBW 36b9cwb9UexFKfBKUhyXKkEQkJPSzToDbMT4hDOI= Date: Wed, 28 Oct 2020 12:43:52 -0700 From: Jaegeuk Kim To: Can Guo Cc: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, kernel-team@android.com, alim.akhtar@samsung.com, avri.altman@wdc.com, bvanassche@acm.org Subject: Re: [PATCH v4 1/5] scsi: ufs: atomic update for clkgating_enable Message-ID: <20201028194352.GA3060274@google.com> References: <20201026195124.363096-1-jaegeuk@kernel.org> <20201026195124.363096-2-jaegeuk@kernel.org> <20d1c2ca06e95beb207fd4ba1b61dc80@codeaurora.org> <20201027033311.GA1745317@google.com> <76df977d164683c7404d2dc702f2e5ad@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <76df977d164683c7404d2dc702f2e5ad@codeaurora.org> Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 10/27, Can Guo wrote: > On 2020-10-27 11:33, Jaegeuk Kim wrote: > > On 10/27, Can Guo wrote: > > > On 2020-10-27 03:51, Jaegeuk Kim wrote: > > > > From: Jaegeuk Kim > > > > > > > > When giving a stress test which enables/disables clkgating, we hit > > > > device > > > > timeout sometimes. This patch avoids subtle racy condition to address > > > > it. > > > > > > > > Note that, this requires a patch to address the device stuck by > > > > REQ_CLKS_OFF in > > > > __ufshcd_release(). > > > > > > > > The fix is "scsi: ufs: avoid to call REQ_CLKS_OFF to CLKS_OFF". > > > > > > Why don't you just squash the fix into this one? > > > > I'm seeing this patch just revealed that problem. > > That scenario (back to back calling of ufshcd_release()) only happens > when you stress the clkgate_enable sysfs node, so let's keep the fix > as one to make things simple. What do you think? If we don't have this patch, do you think this issue won't happen at all? > > Thanks, > > Can Guo. > > > > > > > > > Thanks, > > > > > > Can Guo. > > > > > > > > > > > Signed-off-by: Jaegeuk Kim > > > > --- > > > > drivers/scsi/ufs/ufshcd.c | 12 ++++++------ > > > > 1 file changed, 6 insertions(+), 6 deletions(-) > > > > > > > > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c > > > > index cc8d5f0c3fdc..6c9269bffcbd 100644 > > > > --- a/drivers/scsi/ufs/ufshcd.c > > > > +++ b/drivers/scsi/ufs/ufshcd.c > > > > @@ -1808,19 +1808,19 @@ static ssize_t > > > > ufshcd_clkgate_enable_store(struct device *dev, > > > > return -EINVAL; > > > > > > > > value = !!value; > > > > + > > > > + spin_lock_irqsave(hba->host->host_lock, flags); > > > > if (value == hba->clk_gating.is_enabled) > > > > goto out; > > > > > > > > - if (value) { > > > > - ufshcd_release(hba); > > > > - } else { > > > > - spin_lock_irqsave(hba->host->host_lock, flags); > > > > + if (value) > > > > + __ufshcd_release(hba); > > > > + else > > > > hba->clk_gating.active_reqs++; > > > > - spin_unlock_irqrestore(hba->host->host_lock, flags); > > > > - } > > > > > > > > hba->clk_gating.is_enabled = value; > > > > out: > > > > + spin_unlock_irqrestore(hba->host->host_lock, flags); > > > > return count; > > > > }