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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 44220C2BB55 for ; Thu, 16 Apr 2020 19:49:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 26BD920786 for ; Thu, 16 Apr 2020 19:49:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727897AbgDPTth (ORCPT ); Thu, 16 Apr 2020 15:49:37 -0400 Received: from mga14.intel.com ([192.55.52.115]:57767 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727886AbgDPTtg (ORCPT ); Thu, 16 Apr 2020 15:49:36 -0400 IronPort-SDR: 4CgSil85FYRkVsTZDe2jbtT3F2s8oR5aZSfQ8TCNBasEam03OIFzVF+3TxEQczpe9yQnywyfPj D56ODeg5K4Ww== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Apr 2020 12:49:36 -0700 IronPort-SDR: MLryOXQKq0Z6yWk5ZS0AYhp5ESBc3RJPaCQvN5ugJU8lD1Wi6a9HiDp/fB32y5hLvrY8UTn+4Y KpKcO5aMPnCw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,392,1580803200"; d="scan'208";a="454454609" Received: from tthayer-hp-z620.an.intel.com (HELO [10.122.105.146]) ([10.122.105.146]) by fmsmga005.fm.intel.com with ESMTP; 16 Apr 2020 12:49:35 -0700 Reply-To: thor.thayer@linux.intel.com Subject: Re: [PATCH] i2c: altera: Fix race between xfer_msg and isr thread To: Atsushi Nemoto , linux-i2c@vger.kernel.org Cc: tomonori.sakita@sord.co.jp References: <20200410.100640.1949609603287475131.atsushi.nemoto@sord.co.jp> From: Thor Thayer Message-ID: <4f874ee2-3828-047a-78b1-ccbe674c0ff3@linux.intel.com> Date: Thu, 16 Apr 2020 14:49:40 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 MIME-Version: 1.0 In-Reply-To: <20200410.100640.1949609603287475131.atsushi.nemoto@sord.co.jp> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On 4/9/20 8:06 PM, Atsushi Nemoto wrote: > Use a mutex to protect access to idev->msg_len, idev->buf, etc. which > are modified by both altr_i2c_xfer_msg() and altr_i2c_isr(). > > Signed-off-by: Atsushi Nemoto > --- Acked-by: Thor Thayer > drivers/i2c/busses/i2c-altera.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/drivers/i2c/busses/i2c-altera.c b/drivers/i2c/busses/i2c-altera.c > index 20ef63820c77..3db7d77c5a1e 100644 > --- a/drivers/i2c/busses/i2c-altera.c > +++ b/drivers/i2c/busses/i2c-altera.c > @@ -70,6 +70,7 @@ > * @isr_mask: cached copy of local ISR enables. > * @isr_status: cached copy of local ISR status. > * @lock: spinlock for IRQ synchronization. > + * @mutex: mutex for IRQ thread. > */ > struct altr_i2c_dev { > void __iomem *base; > @@ -86,6 +87,7 @@ struct altr_i2c_dev { > u32 isr_mask; > u32 isr_status; > spinlock_t lock; /* IRQ synchronization */ > + struct mutex mutex; > }; > > static void > @@ -245,10 +247,11 @@ static irqreturn_t altr_i2c_isr(int irq, void *_dev) > struct altr_i2c_dev *idev = _dev; > u32 status = idev->isr_status; > > + mutex_lock(&idev->mutex); > if (!idev->msg) { > dev_warn(idev->dev, "unexpected interrupt\n"); > altr_i2c_int_clear(idev, ALTR_I2C_ALL_IRQ); > - return IRQ_HANDLED; > + goto out; > } > read = (idev->msg->flags & I2C_M_RD) != 0; > > @@ -301,6 +304,8 @@ static irqreturn_t altr_i2c_isr(int irq, void *_dev) > complete(&idev->msg_complete); > dev_dbg(idev->dev, "Message Complete\n"); > } > +out: > + mutex_unlock(&idev->mutex); > > return IRQ_HANDLED; > } > @@ -312,6 +317,7 @@ static int altr_i2c_xfer_msg(struct altr_i2c_dev *idev, struct i2c_msg *msg) > u32 value; > u8 addr = i2c_8bit_addr_from_msg(msg); > > + mutex_lock(&idev->mutex); > idev->msg = msg; > idev->msg_len = msg->len; > idev->buf = msg->buf; > @@ -336,6 +342,7 @@ static int altr_i2c_xfer_msg(struct altr_i2c_dev *idev, struct i2c_msg *msg) > altr_i2c_int_enable(idev, imask, true); > altr_i2c_fill_tx_fifo(idev); > } > + mutex_unlock(&idev->mutex); > > time_left = wait_for_completion_timeout(&idev->msg_complete, > ALTR_I2C_XFER_TIMEOUT); > @@ -410,6 +417,7 @@ static int altr_i2c_probe(struct platform_device *pdev) > idev->dev = &pdev->dev; > init_completion(&idev->msg_complete); > spin_lock_init(&idev->lock); > + mutex_init(&idev->mutex); > > val = device_property_read_u32(idev->dev, "fifo-size", > &idev->fifo_size); >