From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0DA8A168C2 for ; Mon, 8 May 2023 10:21:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8711CC433D2; Mon, 8 May 2023 10:21:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1683541266; bh=sXB2VzvqV8lZY4Fd5ULxR3iga7hLhUnsZRdA96+J/cY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UE7pSvBPPjpr+0wuE7Z4F3q0eqseh1El6emtxW8d+qGWT5q5u2i19dqdOrX//Jtyb whdzZcn7PRZgjYEpqQdRd/8prvGVZpaOtD29PHphTkfHMHSJAdX7Z9Gm6Ni17u1RSD r+NbpuO3qJ9IHWuA4dlGZRZv36UQW5n1Y5iwN2jc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, William Breathitt Gray , Stable@vger.kernel.org, Jonathan Cameron Subject: [PATCH 6.2 059/663] iio: addac: stx104: Fix race condition for stx104_write_raw() Date: Mon, 8 May 2023 11:38:05 +0200 Message-Id: <20230508094430.402054900@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230508094428.384831245@linuxfoundation.org> References: <20230508094428.384831245@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: William Breathitt Gray commit 9740827468cea80c42db29e7171a50e99acf7328 upstream. The priv->chan_out_states array and actual DAC value can become mismatched if stx104_write_raw() is called concurrently. Prevent such a race condition by utilizing a mutex. Fixes: 97a445dad37a ("iio: Add IIO support for the DAC on the Apex Embedded Systems STX104") Signed-off-by: William Breathitt Gray Link: https://lore.kernel.org/r/c95c9a77fcef36b2a052282146950f23bbc1ebdc.1680790580.git.william.gray@linaro.org Cc: Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman --- drivers/iio/addac/stx104.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/drivers/iio/addac/stx104.c +++ b/drivers/iio/addac/stx104.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -69,10 +70,12 @@ struct stx104_reg { /** * struct stx104_iio - IIO device private data structure + * @lock: synchronization lock to prevent I/O race conditions * @chan_out_states: channels' output states * @reg: I/O address offset for the device registers */ struct stx104_iio { + struct mutex lock; unsigned int chan_out_states[STX104_NUM_OUT_CHAN]; struct stx104_reg __iomem *reg; }; @@ -182,9 +185,12 @@ static int stx104_write_raw(struct iio_d if ((unsigned int)val > 65535) return -EINVAL; + mutex_lock(&priv->lock); + priv->chan_out_states[chan->channel] = val; iowrite16(val, &priv->reg->dac[chan->channel]); + mutex_unlock(&priv->lock); return 0; } return -EINVAL; @@ -355,6 +361,8 @@ static int stx104_probe(struct device *d indio_dev->name = dev_name(dev); + mutex_init(&priv->lock); + /* configure device for software trigger operation */ iowrite8(0, &priv->reg->acr);