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=-11.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 2AE53C433E1 for ; Thu, 20 Aug 2020 17:52:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B13A208B3 for ; Thu, 20 Aug 2020 17:52:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Paw7cVq8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726809AbgHTRwj (ORCPT ); Thu, 20 Aug 2020 13:52:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50128 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725859AbgHTRwh (ORCPT ); Thu, 20 Aug 2020 13:52:37 -0400 Received: from mail-pl1-x641.google.com (mail-pl1-x641.google.com [IPv6:2607:f8b0:4864:20::641]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 19146C061385; Thu, 20 Aug 2020 10:52:37 -0700 (PDT) Received: by mail-pl1-x641.google.com with SMTP id v16so1392341plo.1; Thu, 20 Aug 2020 10:52:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=SO5U3LrCCVrf0dhuFlFyMlSOUAOsC6v7W5XQx077kFg=; b=Paw7cVq8IFNYWJuVDtDRqbXOeBEhfkSKmXF4VPw4sZ3HY7RS0bmIUeryQL9QLF9Ag1 3JA54+ZzAsWPyuMqhr0rLj3AxuMlWxcc/G+HScpYXRhNpnIYw7/9HXs9yZAsawCVtD5t QWaJ7sgIwbwyqsXGvYGn/pBDcYVUqWGiLe7fjfnA9Hj37ghG03btEL4DNCNRr6GaW17p 5E6bzkjwoABE59EcUkMP+6fLwQXH0YVXU+DcMdjD4DAcoNDk6aIDX1GcILDbJnx5hf8s LsZ2UQwJ3SxFes81ci5/BoKNPJLTIoV4OiRG8RoAqQiUe+fb0duAIFemxcuSx2ZKPoB0 pYgA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=SO5U3LrCCVrf0dhuFlFyMlSOUAOsC6v7W5XQx077kFg=; b=t8hReHGnbHo+gHUgfnfl7Kq0on2ZbDmCTFH7UX73A7Rm+ihISyreOKmA8BQJh5hfGU ByyrlV3MSE0bap6ncFK1+MWfUMaUITjlvrUw5vqUpC/IXnM7b6qvCANQg5Qa5bzc/19m n/Oe4uhrmALKu4M0odK6NIJ1xDfsw1VkWEpMH3dYgQwjv7WEvEurgIzov3P0cs7QQT5D jy80jtMf1r+zv1W1fQbG0w6bajg6jDYeBYSZWU8w47ObBnM11DFNwbAKTdzSVSm5W54j Vo6mpaCHQVPf59P/TGTKo89LaBm7FQv1S42epraYTcMkPGebjE6H6h/CdQq6H43+90U4 AxLA== X-Gm-Message-State: AOAM533wiRxGPqS9JGv7nudYy4+VdnDejNv+0SHCeyigjg/HUdFamth+ RYIaGo7qIIKRhC8ZL3443g== X-Google-Smtp-Source: ABdhPJzgjNLdGHMdCDp5swqoxlSW24QwZJ+2gkR4xTOfq2s5l36kJ4AyJCj3jEGPSK/jRxQQePOPjg== X-Received: by 2002:a17:90a:3b09:: with SMTP id d9mr3533629pjc.210.1597945956504; Thu, 20 Aug 2020 10:52:36 -0700 (PDT) Received: from madhuparna-HP-Notebook ([2409:4071:230b:2f0d:b051:6744:d734:a674]) by smtp.gmail.com with ESMTPSA id d93sm2918274pjk.44.2020.08.20.10.52.32 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 20 Aug 2020 10:52:35 -0700 (PDT) From: Madhuparna Bhowmik X-Google-Original-From: Madhuparna Bhowmik Date: Thu, 20 Aug 2020 23:22:28 +0530 To: Paul Cercueil Cc: madhuparnabhowmik10@gmail.com, dan.j.williams@intel.com, vkoul@kernel.org, dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, andrianov@ispras.ru, ldv-project@linuxtesting.org Subject: Re: [PATCH] drivers/dma/dma-jz4780: Fix race condition between probe and irq handler Message-ID: <20200820175228.GA7168@madhuparna-HP-Notebook> References: <20200816072253.13817-1-madhuparnabhowmik10@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org On Thu, Aug 20, 2020 at 01:59:23PM +0200, Paul Cercueil wrote: > Hi, > > Le dim. 16 août 2020 à 12:52, madhuparnabhowmik10@gmail.com a écrit : > > From: Madhuparna Bhowmik > > > > In probe IRQ is requested before zchan->id is initialized which can be > > read in the irq handler. Hence, shift request irq and enable clock after > > other initializations complete. Here, enable clock part is not part of > > the race, it is just shifted down after request_irq to keep the error > > path same as before. > > > > Found by Linux Driver Verification project (linuxtesting.org). > > > > Signed-off-by: Madhuparna Bhowmik > > I don't think there is a race at all, the interrupt handler won't be called > before the DMA is registered. > > More importantly, this patch will break things, as there are now register > writes in the probe before the clock is enabled. > Okay, thanks for reviewing the patch anyway, and sorry for the trouble. Regards, Madhuparna > Cheers, > -Paul > > > --- > > drivers/dma/dma-jz4780.c | 44 ++++++++++++++++++++-------------------- > > 1 file changed, 22 insertions(+), 22 deletions(-) > > > > diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c > > index 448f663da89c..5cbc8c3bd6c7 100644 > > --- a/drivers/dma/dma-jz4780.c > > +++ b/drivers/dma/dma-jz4780.c > > @@ -879,28 +879,6 @@ static int jz4780_dma_probe(struct platform_device > > *pdev) > > return -EINVAL; > > } > > > > - ret = platform_get_irq(pdev, 0); > > - if (ret < 0) > > - return ret; > > - > > - jzdma->irq = ret; > > - > > - ret = request_irq(jzdma->irq, jz4780_dma_irq_handler, 0, > > dev_name(dev), > > - jzdma); > > - if (ret) { > > - dev_err(dev, "failed to request IRQ %u!\n", jzdma->irq); > > - return ret; > > - } > > - > > - jzdma->clk = devm_clk_get(dev, NULL); > > - if (IS_ERR(jzdma->clk)) { > > - dev_err(dev, "failed to get clock\n"); > > - ret = PTR_ERR(jzdma->clk); > > - goto err_free_irq; > > - } > > - > > - clk_prepare_enable(jzdma->clk); > > - > > /* Property is optional, if it doesn't exist the value will remain 0. > > */ > > of_property_read_u32_index(dev->of_node, "ingenic,reserved-channels", > > 0, &jzdma->chan_reserved); > > @@ -949,6 +927,28 @@ static int jz4780_dma_probe(struct platform_device > > *pdev) > > jzchan->vchan.desc_free = jz4780_dma_desc_free; > > } > > > > + ret = platform_get_irq(pdev, 0); > > + if (ret < 0) > > + return ret; > > + > > + jzdma->irq = ret; > > + > > + ret = request_irq(jzdma->irq, jz4780_dma_irq_handler, 0, > > dev_name(dev), > > + jzdma); > > + if (ret) { > > + dev_err(dev, "failed to request IRQ %u!\n", jzdma->irq); > > + return ret; > > + } > > + > > + jzdma->clk = devm_clk_get(dev, NULL); > > + if (IS_ERR(jzdma->clk)) { > > + dev_err(dev, "failed to get clock\n"); > > + ret = PTR_ERR(jzdma->clk); > > + goto err_free_irq; > > + } > > + > > + clk_prepare_enable(jzdma->clk); > > + > > ret = dmaenginem_async_device_register(dd); > > if (ret) { > > dev_err(dev, "failed to register device\n"); > > -- > > 2.17.1 > > > >