FAILED: patch "[PATCH] iio: addac: stx104: Fix race condition for stx104_write_raw()" failed to apply to 4.19-stable tree

PATCH [email protected] 1 participant 1 message May 6, 2023

Subsystems (3)

Stable branch IIO Apex embedded systems STX104 IIO driver

lore

Share & tools

lore

[email protected]

author maintainer

2023-05-06 05:59 UTC #0 lore raw

The patch below does not apply to the 4.19-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 <[email protected]>.

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-4.19.y
git checkout FETCH_HEAD
git cherry-pick -x 9740827468cea80c42db29e7171a50e99acf7328
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023050619-swapping-saga-797e@gregkh' --subject-prefix 'PATCH 4.19.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 <[email protected]>
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 <[email protected]>

Link https://lore.kernel.org/r/c95c9a77fcef36b2a052282146950f23bbc1ebdc.1680790580.git.william.gray@linaro.org open here

Cc <[email protected]>

Signed-off-by Jonathan Cameron <[email protected]>

drivers/iio/addac/stx104.c +8 -0

index e45b70aa5bb7..4239aafe42fc 100644
@@ -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);