[PATCH 0/3] iio: frequency: ad9834: driver cleanup

[PATCH 0/3] iio: frequency: ad9834: driver cleanup

[Joshua Crofts]

This series deals with cleaning up includes, changing sprintf()
to sysfs_emit() for better writing to userspace and adding mutexes
when reading st->control to prevent data races.

Joshua Crofts (3):
  iio: frequency: ad9834: clean up includes
  iio: frequency: ad9834: change sprintf() to sysfs_emit()
  iio: frequency: ad9834: add mutex_lock() when reading st->control

 drivers/staging/iio/frequency/ad9834.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

-- 
2.47.3

[PATCH 1/3] iio: frequency: ad9834: clean up includes

[Joshua Crofts]

Clean up includes by removing proxy kernel.h header,
add bitops.h header and order includes for better
readability.

Signed-off-by: Joshua Crofts <joshua.crofts1@gmail.com>
---
 drivers/staging/iio/frequency/ad9834.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/staging/iio/frequency/ad9834.c b/drivers/staging/iio/frequency/ad9834.c
index d339d5e8e0..eed4e08920 100644
--- a/drivers/staging/iio/frequency/ad9834.c
+++ b/drivers/staging/iio/frequency/ad9834.c
@@ -5,19 +5,19 @@
  * Copyright 2010-2011 Analog Devices Inc.
  */
 
+#include <asm/div64.h>
+#include <linux/bitops.h>
 #include <linux/clk.h>
-#include <linux/interrupt.h>
-#include <linux/workqueue.h>
 #include <linux/device.h>
-#include <linux/kernel.h>
-#include <linux/slab.h>
-#include <linux/sysfs.h>
-#include <linux/list.h>
-#include <linux/spi/spi.h>
-#include <linux/regulator/consumer.h>
 #include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
 #include <linux/module.h>
-#include <asm/div64.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/sysfs.h>
+#include <linux/workqueue.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
-- 
2.47.3

[PATCH 2/3] iio: frequency: ad9834: change sprintf() to sysfs_emit()

[Joshua Crofts]

Change instances of sprintf() to sysfs_emit() as returning
formatted values to user space should be done using this
function.

Signed-off-by: Joshua Crofts <joshua.crofts1@gmail.com>
---
 drivers/staging/iio/frequency/ad9834.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/iio/frequency/ad9834.c b/drivers/staging/iio/frequency/ad9834.c
index eed4e08920..9499e05a73 100644
--- a/drivers/staging/iio/frequency/ad9834.c
+++ b/drivers/staging/iio/frequency/ad9834.c
@@ -290,7 +290,7 @@ ssize_t ad9834_show_out0_wavetype_available(struct device *dev,
 	else
 		str = "sine triangle";
 
-	return sprintf(buf, "%s\n", str);
+	return sysfs_emit(buf, "%s\n", str);
 }
 
 static IIO_DEVICE_ATTR(out_altvoltage0_out0_wavetype_available, 0444,
@@ -310,7 +310,7 @@ ssize_t ad9834_show_out1_wavetype_available(struct device *dev,
 	else
 		str = "square";
 
-	return sprintf(buf, "%s\n", str);
+	return sysfs_emit(buf, "%s\n", str);
 }
 
 static IIO_DEVICE_ATTR(out_altvoltage0_out1_wavetype_available, 0444,
-- 
2.47.3

[PATCH 3/3] iio: frequency: ad9834: add mutex_lock() when reading st->control

[Joshua Crofts]

Add mutex_lock() and mutex_unlock() when reading st->control to
prevent data races as st->control is actively modified by
sysfs _write and _store functions.

Signed-off-by: Joshua Crofts <joshua.crofts1@gmail.com>
---
 drivers/staging/iio/frequency/ad9834.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/staging/iio/frequency/ad9834.c b/drivers/staging/iio/frequency/ad9834.c
index 9499e05a73..33570474c4 100644
--- a/drivers/staging/iio/frequency/ad9834.c
+++ b/drivers/staging/iio/frequency/ad9834.c
@@ -283,12 +283,14 @@ ssize_t ad9834_show_out0_wavetype_available(struct device *dev,
 	struct ad9834_state *st = iio_priv(indio_dev);
 	char *str;
 
+	mutex_lock(&st->lock);
 	if (st->devid == ID_AD9833 || st->devid == ID_AD9837)
 		str = "sine triangle square";
 	else if (st->control & AD9834_OPBITEN)
 		str = "sine";
 	else
 		str = "sine triangle";
+	mutex_unlock(&st->lock);
 
 	return sysfs_emit(buf, "%s\n", str);
 }
@@ -305,10 +307,12 @@ ssize_t ad9834_show_out1_wavetype_available(struct device *dev,
 	struct ad9834_state *st = iio_priv(indio_dev);
 	char *str;
 
+	mutex_lock(&st->lock);
 	if (st->control & AD9834_MODE)
 		str = "";
 	else
 		str = "square";
+	mutex_unlock(&st->lock);
 
 	return sysfs_emit(buf, "%s\n", str);
 }
-- 
2.47.3

Re: [PATCH 2/3] iio: frequency: ad9834: change sprintf() to sysfs_emit()

[Dan Carpenter]

On Tue, Apr 14, 2026 at 09:12:49AM +0000, Joshua Crofts wrote:
> Change instances of sprintf() to sysfs_emit() as returning
> formatted values to user space should be done using this
> function.
> 
> Signed-off-by: Joshua Crofts <joshua.crofts1@gmail.com>

Someone beat you to it.  You're working against an old tree.

regards,
dan carpenter

Re: [PATCH 3/3] iio: frequency: ad9834: add mutex_lock() when reading st->control

[Dan Carpenter]

On Tue, Apr 14, 2026 at 09:12:50AM +0000, Joshua Crofts wrote:
> Add mutex_lock() and mutex_unlock() when reading st->control to
> prevent data races as st->control is actively modified by
> sysfs _write and _store functions.
> 
> Signed-off-by: Joshua Crofts <joshua.crofts1@gmail.com>
> ---

This doesn't matter in real life.  "Oops, the root user tried
really hard to do something stupid and got "square" as the output
a fraction of a milisecond longer than they were supposed to."

Is there a tool which detects and complains about this?

regards,
dan carpenter

Re: [PATCH 3/3] iio: frequency: ad9834: add mutex_lock() when reading st->control

[Joshua Crofts]

On Tue, 14 Apr 2026 at 11:36, Dan Carpenter <error27@gmail.com> wrote:
> This doesn't matter in real life.  "Oops, the root user tried
> really hard to do something stupid and got "square" as the output
> a fraction of a milisecond longer than they were supposed to."
>
> Is there a tool which detects and complains about this?

No, no tool complained about it, I honestly just thought it's best practice to
add a mutex_lock() given that st->control is "volatile".

-- 
Kind regards

CJD

Re: [PATCH 1/3] iio: frequency: ad9834: clean up includes

[Andy Shevchenko]

On Tue, Apr 14, 2026 at 09:12:48AM +0000, Joshua Crofts wrote:
> Clean up includes by removing proxy kernel.h header,
> add bitops.h header and order includes for better
> readability.

...

> +#include <asm/div64.h>

This should go after generic linux/*. In other words, it was originally placed
correctly.

> +#include <linux/bitops.h>
>  #include <linux/clk.h>
> -#include <linux/interrupt.h>
> -#include <linux/workqueue.h>

>  #include <linux/device.h>

Also check for usage of this one.

> -#include <linux/kernel.h>
> -#include <linux/slab.h>
> -#include <linux/sysfs.h>
> -#include <linux/list.h>
> -#include <linux/spi/spi.h>
> -#include <linux/regulator/consumer.h>
>  #include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/list.h>
>  #include <linux/module.h>
> -#include <asm/div64.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +#include <linux/spi/spi.h>
> +#include <linux/sysfs.h>
> +#include <linux/workqueue.h>

-- 
With Best Regards,
Andy Shevchenko