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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1B58FEB64D7 for ; Mon, 26 Jun 2023 16:42:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229965AbjFZQmp (ORCPT ); Mon, 26 Jun 2023 12:42:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37600 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229763AbjFZQmo (ORCPT ); Mon, 26 Jun 2023 12:42:44 -0400 Received: from mail-oa1-x2c.google.com (mail-oa1-x2c.google.com [IPv6:2001:4860:4864:20::2c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 57047E54 for ; Mon, 26 Jun 2023 09:42:43 -0700 (PDT) Received: by mail-oa1-x2c.google.com with SMTP id 586e51a60fabf-1aa34b210c9so3516847fac.0 for ; Mon, 26 Jun 2023 09:42:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; t=1687797762; x=1690389762; h=in-reply-to:from:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to; bh=NEJaYRbEROMg1Ln3KZ2JIS/7joPtDvOQzNjf5GyCbDY=; b=HZveeJfq8hJPm2KHVK1DLQHtnEOH9jbYMJex026EpB+aD/vcldWXeo4DVRvZq7Kw27 6ua6jCsusS5wSGwrtPv8f6RaVdD1CS3RltM4LkS/d6jzwIDbdiwZXDiv2/3GYdrve0RS HN79rDMw8G7tVgJiD1nps++VSy1dn4gUpI+ss= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1687797762; x=1690389762; h=in-reply-to:from:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=NEJaYRbEROMg1Ln3KZ2JIS/7joPtDvOQzNjf5GyCbDY=; b=Xa9zcIjWc9PaIurh+MHfqWh24yDRF34Z/dSegOEQ6WvVSfaLm3JQ8v3KcGzioq0LYk 9peOslI/D4i34d/aZMg5oBTiObv8aClHQAfTBVuRWPUhfDN7KM84fnLGOG4GlV1wwhFw hGr92mXfuDoAm4PEVnXOz8tipI/j4/tXSB506eaVjqPwd8L59nA8ukfdF5UokIyijtbh fMhfQUPYtumIxmy1TwC5nNWIGJS1dqMZrQmOsZ/cv+h3H2XwOcZoG8rhyooqMxmnO+Pj Vh8cv6oDrug3a+J1L2PdbftFaWugrxsOxq3AYPNoBLsH7Lmys/3YGh7rWH2KhkBSD5Uh LlPQ== X-Gm-Message-State: AC+VfDwlWIaoqNX5WvuexaE1dWTgzvSjMvJbT0i5Yi5fAeZy1lgpcDWG VRttlFHLNh6X4lLVysmRaJsAj/tJiQD93eialOVyNw== X-Google-Smtp-Source: ACHHUZ6ryBVYZ475S6GBd7/gw3WoZ/8NKnrQ7gQEEdXwHEYeCp5+Im/cmq+hiNQnntW/5qFmgR81Ow== X-Received: by 2002:a05:6808:128d:b0:3a0:30c4:5d45 with SMTP id a13-20020a056808128d00b003a030c45d45mr28450600oiw.33.1687797762449; Mon, 26 Jun 2023 09:42:42 -0700 (PDT) Received: from [10.136.64.163] ([192.19.161.248]) by smtp.gmail.com with ESMTPSA id g6-20020a635206000000b0054fd46531a1sm4319710pgb.5.2023.06.26.09.42.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 Jun 2023 09:42:41 -0700 (PDT) Message-ID: Date: Mon, 26 Jun 2023 09:42:39 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH] i2c: bcm-iproc: Fix bcm_iproc_i2c_isr deadlock issue To: YE Chengfeng , "andi.shyti@kernel.org" , "rjui@broadcom.com" , "sbranden@broadcom.com" Cc: "linux-i2c@vger.kernel.org" , Linux ARM , "linux-kernel@vger.kernel.org" , "bcm-kernel-feedback-list@broadcom.com" References: From: Ray Jui In-Reply-To: Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="0000000000001bbb1505ff0b0a64" Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org --0000000000001bbb1505ff0b0a64 Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Chengfeng, On 6/24/2023 12:36 PM, YE Chengfeng wrote: > iproc_i2c_rd_reg and iproc_i2c_wr_reg are called from both > interrupt context (e.g. bcm_iproc_i2c_isr) and process context > (e.g. bcm_iproc_i2c_suspend). Therefore, interrupts should be > disabled to avoid potential deadlock. To prevent this deadlock, > use spin_lock_irqsave. > > Signed-off-by: Chengfeng Ye > --- >  drivers/i2c/busses/i2c-bcm-iproc.c | 10 ++++++---- >  1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c > index 85d8a6b04885..d02245e4db8c 100644 > --- a/drivers/i2c/busses/i2c-bcm-iproc.c > +++ b/drivers/i2c/busses/i2c-bcm-iproc.c > @@ -233,13 +233,14 @@ static inline u32 iproc_i2c_rd_reg(struct bcm_iproc_i2c_dev *iproc_i2c, >                                    u32 offset) >  { >         u32 val; > +       unsigned long flags; > >         if (iproc_i2c->idm_base) { > -               spin_lock(&iproc_i2c->idm_lock); > +               spin_lock_irqsave(&iproc_i2c->idm_lock, flags); >                 writel(iproc_i2c->ape_addr_mask, >                        iproc_i2c->idm_base + IDM_CTRL_DIRECT_OFFSET); >                 val = readl(iproc_i2c->base + offset); > -               spin_unlock(&iproc_i2c->idm_lock); > +               spin_unlock_irqrestore(&iproc_i2c->idm_lock, flags); >         } else { >                 val = readl(iproc_i2c->base + offset); >         } > @@ -250,12 +251,13 @@ static inline u32 iproc_i2c_rd_reg(struct bcm_iproc_i2c_dev *iproc_i2c, >  static inline void iproc_i2c_wr_reg(struct bcm_iproc_i2c_dev *iproc_i2c, >                                     u32 offset, u32 val) >  { > +       unsigned long flags; >         if (iproc_i2c->idm_base) { > -               spin_lock(&iproc_i2c->idm_lock); > +               spin_lock_irqsave(&iproc_i2c->idm_lock, flags); >                 writel(iproc_i2c->ape_addr_mask, >                        iproc_i2c->idm_base + IDM_CTRL_DIRECT_OFFSET); >                 writel(val, iproc_i2c->base + offset); > -               spin_unlock(&iproc_i2c->idm_lock); > +               spin_unlock_irqrestore(&iproc_i2c->idm_lock, flags); >         } else { >                 writel(val, iproc_i2c->base + offset); >         } > --  > 2.17.1 This fix looks good to me. Thanks. Just curious, did you actually see a race condition issue as a result of this, or the fix is done completely based on the analysis of the code? 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