The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.14.y git checkout FETCH_HEAD git cherry-pick -x 9740827468cea80c42db29e7171a50e99acf7328 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023050619-revolt-matted-623b@gregkh' --subject-prefix 'PATCH 4.14.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 9740827468cea80c42db29e7171a50e99acf7328 Mon Sep 17 00:00:00 2001 From: William Breathitt Gray william.gray@linaro.org Date: Thu, 6 Apr 2023 10:40:10 -0400 Subject: [PATCH] iio: addac: stx104: Fix race condition for stx104_write_raw()
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 william.gray@linaro.org Link: https://lore.kernel.org/r/c95c9a77fcef36b2a052282146950f23bbc1ebdc.168079058... Cc: Stable@vger.kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com
diff --git a/drivers/iio/addac/stx104.c b/drivers/iio/addac/stx104.c index e45b70aa5bb7..4239aafe42fc 100644 --- a/drivers/iio/addac/stx104.c +++ b/drivers/iio/addac/stx104.c @@ -15,6 +15,7 @@ #include <linux/kernel.h> #include <linux/module.h> #include <linux/moduleparam.h> +#include <linux/mutex.h> #include <linux/spinlock.h> #include <linux/types.h>
@@ -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; }; @@ -178,9 +181,12 @@ static int stx104_write_raw(struct iio_dev *indio_dev, 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; @@ -351,6 +357,8 @@ static int stx104_probe(struct device *dev, unsigned int id)
indio_dev->name = dev_name(dev);
+ mutex_init(&priv->lock); + /* configure device for software trigger operation */ iowrite8(0, &priv->reg->acr);