* Re: [PATCH v2] staging: iio: adc: ad7816: Protect sysfs attributes with mutex
2026-09-20 9:15 [PATCH v2] staging: iio: adc: ad7816: Protect sysfs attributes with mutex Abdelnasser Hussein
@ 2026-09-21 3:49 ` Jonathan Cameron
2026-09-23 6:13 ` kernel test robot
2026-09-23 12:44 ` kernel test robot
2 siblings, 0 replies; 4+ messages in thread
From: Jonathan Cameron @ 2026-09-21 3:49 UTC (permalink / raw)
To: Abdelnasser Hussein
Cc: gregkh, nuno.sa, Michael.Hennerich, dlechner, andy, linux,
linux-iio, linux-staging, linux-kernel, joshua.crofts1, error27
On Sun, 20 Sep 2026 12:15:22 +0300
Abdelnasser Hussein <abdelnasserhussein11@gmail.com> wrote:
> The sysfs store functions (ad7816_store_mode and ad7816_store_channel)
> modify the device state and toggle GPIO pins. If accessed concurrently
> by userspace during an ongoing SPI transfer, this could corrupt the
> SPI transaction.
See below. One of them doesn't seem to have that possible affect.
Thanks,
Jonathan
>
> Add the existing chip->lock guard to these functions to serialize
> access and prevent race conditions.
>
> Fixes: 7924425db04a ("staging: iio: adc: new driver for AD7816 devices")
> Suggested-by: Joshua Crofts <joshua.crofts1@gmail.com>
> Reviewed-by: Joshua Crofts <joshua.crofts1@gmail.com>
> Signed-off-by: Abdelnasser Hussein <abdelnasserhussein11@gmail.com>
> ---
> Changes in v2:
> - Added a blank line after guard(mutex) statements as requested by Joshua.
> - Added Fixes tag as requested by Dan.
> - Collected Reviewed-by tag from Joshua.
>
> drivers/staging/iio/adc/ad7816.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/staging/iio/adc/ad7816.c b/drivers/staging/iio/adc/ad7816.c
> index f76f0215119a..2a15d7598abb 100644
> --- a/drivers/staging/iio/adc/ad7816.c
> +++ b/drivers/staging/iio/adc/ad7816.c
> @@ -143,6 +143,8 @@ static ssize_t ad7816_store_mode(struct device *dev,
> struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> struct ad7816_chip_info *chip = iio_priv(indio_dev);
>
> + guard(mutex)(&chip->lock);
> +
> if (strcmp(buf, "full") == 0) {
> gpiod_set_value(chip->rdwr_pin, 1);
> chip->mode = AD7816_FULL;
> @@ -207,6 +209,8 @@ static ssize_t ad7816_store_channel(struct device *dev,
> return -EINVAL;
> }
>
> + guard(mutex)(&chip->lock);
This isn't toggling pins or modifying anything on the device state side
of things. So at very least the commit message needs to be expanded to
what this is doing that needs a lock.
> +
> chip->channel_id = data;
>
> return len;
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH v2] staging: iio: adc: ad7816: Protect sysfs attributes with mutex
2026-09-20 9:15 [PATCH v2] staging: iio: adc: ad7816: Protect sysfs attributes with mutex Abdelnasser Hussein
2026-09-21 3:49 ` Jonathan Cameron
@ 2026-09-23 6:13 ` kernel test robot
2026-09-23 12:44 ` kernel test robot
2 siblings, 0 replies; 4+ messages in thread
From: kernel test robot @ 2026-09-23 6:13 UTC (permalink / raw)
To: Abdelnasser Hussein, jic23, gregkh, nuno.sa, Michael.Hennerich
Cc: oe-kbuild-all, dlechner, andy, linux, linux-iio, linux-staging,
linux-kernel, joshua.crofts1, error27, Abdelnasser Hussein
Hi Abdelnasser,
kernel test robot noticed the following build errors:
[auto build test ERROR on staging/staging-testing]
url: https://github.com/intel-lab-lkp/linux/commits/Abdelnasser-Hussein/staging-iio-adc-ad7816-Protect-sysfs-attributes-with-mutex/20260920-121522
base: staging/staging-testing
patch link: https://lore.kernel.org/r/20260920091522.15507-1-abdelnasserhussein11%40gmail.com
patch subject: [PATCH v2] staging: iio: adc: ad7816: Protect sysfs attributes with mutex
config: sparc-randconfig-2001-20260923 (https://download.01.org/0day-ci/archive/20260923/202609230855.IEzAf41u-lkp@intel.com/config)
compiler: sparc-linux-gcc (GCC) 14.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260923/202609230855.IEzAf41u-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202609230855.IEzAf41u-lkp@intel.com/
All errors (new ones prefixed by >>):
In file included from include/linux/irqflags.h:17,
from include/asm-generic/cmpxchg-local.h:6,
from arch/sparc/include/asm/cmpxchg_32.h:67,
from arch/sparc/include/asm/cmpxchg.h:7,
from arch/sparc/include/asm/atomic_32.h:17,
from arch/sparc/include/asm/atomic.h:7,
from include/linux/atomic.h:7,
from include/asm-generic/bitops/lock.h:5,
from arch/sparc/include/asm/bitops_32.h:102,
from arch/sparc/include/asm/bitops.h:7,
from include/linux/bitops.h:67,
from include/linux/kernel.h:23,
from include/linux/interrupt.h:6,
from drivers/staging/iio/adc/ad7816.c:8:
drivers/staging/iio/adc/ad7816.c: In function 'ad7816_store_mode':
>> drivers/staging/iio/adc/ad7816.c:139:27: error: 'struct ad7816_chip_info' has no member named 'lock'
139 | guard(mutex)(&chip->lock);
| ^~
include/linux/cleanup.h:558:37: note: in definition of macro 'WITH_LOCK_GUARD_1_ATTRS'
558 | class_##_name##_constructor(_T), \
| ^~
include/linux/cleanup.h:303:17: note: in expansion of macro 'class_mutex_constructor'
303 | class_##_name##_constructor
| ^~~~~~
include/linux/cleanup.h:423:9: note: in expansion of macro 'CLASS'
423 | CLASS(_name, __UNIQUE_ID(guard))
| ^~~~~
drivers/staging/iio/adc/ad7816.c:139:9: note: in expansion of macro 'guard'
139 | guard(mutex)(&chip->lock);
| ^~~~~
>> drivers/staging/iio/adc/ad7816.c:139:27: error: 'struct ad7816_chip_info' has no member named 'lock'
139 | guard(mutex)(&chip->lock);
| ^~
include/linux/cleanup.h:559:97: note: in definition of macro 'WITH_LOCK_GUARD_1_ATTRS'
559 | *__UNIQUE_ID(unlock) __cleanup(__class_##_name##_cleanup_ctx) = (void *)(unsigned long)(_T)
| ^~
include/linux/cleanup.h:303:17: note: in expansion of macro 'class_mutex_constructor'
303 | class_##_name##_constructor
| ^~~~~~
include/linux/cleanup.h:423:9: note: in expansion of macro 'CLASS'
423 | CLASS(_name, __UNIQUE_ID(guard))
| ^~~~~
drivers/staging/iio/adc/ad7816.c:139:9: note: in expansion of macro 'guard'
139 | guard(mutex)(&chip->lock);
| ^~~~~
drivers/staging/iio/adc/ad7816.c: In function 'ad7816_store_channel':
drivers/staging/iio/adc/ad7816.c:205:27: error: 'struct ad7816_chip_info' has no member named 'lock'
205 | guard(mutex)(&chip->lock);
| ^~
include/linux/cleanup.h:558:37: note: in definition of macro 'WITH_LOCK_GUARD_1_ATTRS'
558 | class_##_name##_constructor(_T), \
| ^~
include/linux/cleanup.h:303:17: note: in expansion of macro 'class_mutex_constructor'
303 | class_##_name##_constructor
| ^~~~~~
include/linux/cleanup.h:423:9: note: in expansion of macro 'CLASS'
423 | CLASS(_name, __UNIQUE_ID(guard))
| ^~~~~
drivers/staging/iio/adc/ad7816.c:205:9: note: in expansion of macro 'guard'
205 | guard(mutex)(&chip->lock);
| ^~~~~
drivers/staging/iio/adc/ad7816.c:205:27: error: 'struct ad7816_chip_info' has no member named 'lock'
205 | guard(mutex)(&chip->lock);
| ^~
include/linux/cleanup.h:559:97: note: in definition of macro 'WITH_LOCK_GUARD_1_ATTRS'
559 | *__UNIQUE_ID(unlock) __cleanup(__class_##_name##_cleanup_ctx) = (void *)(unsigned long)(_T)
| ^~
include/linux/cleanup.h:303:17: note: in expansion of macro 'class_mutex_constructor'
303 | class_##_name##_constructor
| ^~~~~~
include/linux/cleanup.h:423:9: note: in expansion of macro 'CLASS'
423 | CLASS(_name, __UNIQUE_ID(guard))
| ^~~~~
drivers/staging/iio/adc/ad7816.c:205:9: note: in expansion of macro 'guard'
205 | guard(mutex)(&chip->lock);
| ^~~~~
vim +139 drivers/staging/iio/adc/ad7816.c
> 8 #include <linux/interrupt.h>
9 #include <linux/gpio/consumer.h>
10 #include <linux/device.h>
11 #include <linux/kernel.h>
12 #include <linux/slab.h>
13 #include <linux/sysfs.h>
14 #include <linux/list.h>
15 #include <linux/spi/spi.h>
16 #include <linux/module.h>
17
18 #include <linux/iio/iio.h>
19 #include <linux/iio/sysfs.h>
20 #include <linux/iio/events.h>
21
22 /*
23 * AD7816 config masks
24 */
25 #define AD7816_FULL 0x1
26 #define AD7816_PD 0x2
27 #define AD7816_CS_MASK 0x7
28 #define AD7816_CS_MAX 0x4
29
30 /*
31 * AD7816 temperature masks
32 */
33 #define AD7816_VALUE_OFFSET 6
34 #define AD7816_BOUND_VALUE_BASE 0x8
35 #define AD7816_BOUND_VALUE_MIN -95
36 #define AD7816_BOUND_VALUE_MAX 152
37 #define AD7816_TEMP_FLOAT_OFFSET 2
38 #define AD7816_TEMP_FLOAT_MASK 0x3
39
40 /*
41 * struct ad7816_chip_info - chip specific information
42 */
43
44 struct ad7816_chip_info {
45 kernel_ulong_t id;
46 struct spi_device *spi_dev;
47 struct gpio_desc *rdwr_pin;
48 struct gpio_desc *convert_pin;
49 struct gpio_desc *busy_pin;
50 u8 oti_data[AD7816_CS_MAX + 1];
51 u8 channel_id; /* 0 always be temperature */
52 u8 mode;
53 };
54
55 enum ad7816_type {
56 ID_AD7816,
57 ID_AD7817,
58 ID_AD7818,
59 };
60
61 /*
62 * ad7816 data access by SPI
63 */
64 static int ad7816_spi_read(struct ad7816_chip_info *chip, u16 *data)
65 {
66 struct spi_device *spi_dev = chip->spi_dev;
67 int ret;
68 __be16 buf;
69
70 gpiod_set_value(chip->rdwr_pin, 1);
71 gpiod_set_value(chip->rdwr_pin, 0);
72 ret = spi_write(spi_dev, &chip->channel_id, sizeof(chip->channel_id));
73 if (ret < 0) {
74 dev_err(&spi_dev->dev, "SPI channel setting error\n");
75 return ret;
76 }
77 gpiod_set_value(chip->rdwr_pin, 1);
78
79 if (chip->mode == AD7816_PD) { /* operating mode 2 */
80 gpiod_set_value(chip->convert_pin, 1);
81 gpiod_set_value(chip->convert_pin, 0);
82 } else { /* operating mode 1 */
83 gpiod_set_value(chip->convert_pin, 0);
84 gpiod_set_value(chip->convert_pin, 1);
85 }
86
87 if (chip->id == ID_AD7816 || chip->id == ID_AD7817) {
88 while (gpiod_get_value(chip->busy_pin))
89 cpu_relax();
90 }
91
92 gpiod_set_value(chip->rdwr_pin, 0);
93 gpiod_set_value(chip->rdwr_pin, 1);
94 ret = spi_read(spi_dev, &buf, sizeof(*data));
95 if (ret < 0) {
96 dev_err(&spi_dev->dev, "SPI data read error\n");
97 return ret;
98 }
99
100 *data = be16_to_cpu(buf);
101
102 return ret;
103 }
104
105 static int ad7816_spi_write(struct ad7816_chip_info *chip, u8 data)
106 {
107 struct spi_device *spi_dev = chip->spi_dev;
108 int ret;
109
110 gpiod_set_value(chip->rdwr_pin, 1);
111 gpiod_set_value(chip->rdwr_pin, 0);
112 ret = spi_write(spi_dev, &data, sizeof(data));
113 if (ret < 0)
114 dev_err(&spi_dev->dev, "SPI oti data write error\n");
115
116 return ret;
117 }
118
119 static ssize_t ad7816_show_mode(struct device *dev,
120 struct device_attribute *attr,
121 char *buf)
122 {
123 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
124 struct ad7816_chip_info *chip = iio_priv(indio_dev);
125
126 if (chip->mode)
127 return sysfs_emit(buf, "power-save\n");
128 return sysfs_emit(buf, "full\n");
129 }
130
131 static ssize_t ad7816_store_mode(struct device *dev,
132 struct device_attribute *attr,
133 const char *buf,
134 size_t len)
135 {
136 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
137 struct ad7816_chip_info *chip = iio_priv(indio_dev);
138
> 139 guard(mutex)(&chip->lock);
140
141 if (strcmp(buf, "full") == 0) {
142 gpiod_set_value(chip->rdwr_pin, 1);
143 chip->mode = AD7816_FULL;
144 } else {
145 gpiod_set_value(chip->rdwr_pin, 0);
146 chip->mode = AD7816_PD;
147 }
148
149 return len;
150 }
151
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH v2] staging: iio: adc: ad7816: Protect sysfs attributes with mutex
2026-09-20 9:15 [PATCH v2] staging: iio: adc: ad7816: Protect sysfs attributes with mutex Abdelnasser Hussein
2026-09-21 3:49 ` Jonathan Cameron
2026-09-23 6:13 ` kernel test robot
@ 2026-09-23 12:44 ` kernel test robot
2 siblings, 0 replies; 4+ messages in thread
From: kernel test robot @ 2026-09-23 12:44 UTC (permalink / raw)
To: Abdelnasser Hussein, jic23, gregkh, nuno.sa, Michael.Hennerich
Cc: oe-kbuild-all, dlechner, andy, linux, linux-iio, linux-staging,
linux-kernel, joshua.crofts1, error27, Abdelnasser Hussein
Hi Abdelnasser,
kernel test robot noticed the following build errors:
[auto build test ERROR on staging/staging-testing]
url: https://github.com/intel-lab-lkp/linux/commits/Abdelnasser-Hussein/staging-iio-adc-ad7816-Protect-sysfs-attributes-with-mutex/20260920-121522
base: staging/staging-testing
patch link: https://lore.kernel.org/r/20260920091522.15507-1-abdelnasserhussein11%40gmail.com
patch subject: [PATCH v2] staging: iio: adc: ad7816: Protect sysfs attributes with mutex
config: i386-randconfig-2102-20260923 (https://download.01.org/0day-ci/archive/20260923/202609231453.RPvUxbGl-lkp@intel.com/config)
compiler: clang version 22.1.8 (https://github.com/llvm/llvm-project ca7933e47d3a3451d81e72ac174dcb5aa28b59d1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260923/202609231453.RPvUxbGl-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202609231453.RPvUxbGl-lkp@intel.com/
All errors (new ones prefixed by >>):
>> drivers/staging/iio/adc/ad7816.c:139:22: error: no member named 'lock' in 'struct ad7816_chip_info'
139 | guard(mutex)(&chip->lock);
| ~~~~ ^
include/linux/cleanup.h:423:2: note: expanded from macro 'guard'
423 | CLASS(_name, __UNIQUE_ID(guard))
| ^
include/linux/cleanup.h:303:3: note: expanded from macro 'CLASS'
303 | class_##_name##_constructor
| ^
<scratch space>:67:1: note: expanded from here
67 | class_mutex_constructor
| ^
>> drivers/staging/iio/adc/ad7816.c:139:22: error: no member named 'lock' in 'struct ad7816_chip_info'
139 | guard(mutex)(&chip->lock);
| ~~~~ ^
include/linux/cleanup.h:423:2: note: expanded from macro 'guard'
423 | CLASS(_name, __UNIQUE_ID(guard))
| ^
include/linux/cleanup.h:303:3: note: expanded from macro 'CLASS'
303 | class_##_name##_constructor
| ^
<scratch space>:67:1: note: expanded from here
67 | class_mutex_constructor
| ^
drivers/staging/iio/adc/ad7816.c:205:22: error: no member named 'lock' in 'struct ad7816_chip_info'
205 | guard(mutex)(&chip->lock);
| ~~~~ ^
include/linux/cleanup.h:423:2: note: expanded from macro 'guard'
423 | CLASS(_name, __UNIQUE_ID(guard))
| ^
include/linux/cleanup.h:303:3: note: expanded from macro 'CLASS'
303 | class_##_name##_constructor
| ^
<scratch space>:107:1: note: expanded from here
107 | class_mutex_constructor
| ^
drivers/staging/iio/adc/ad7816.c:205:22: error: no member named 'lock' in 'struct ad7816_chip_info'
205 | guard(mutex)(&chip->lock);
| ~~~~ ^
include/linux/cleanup.h:423:2: note: expanded from macro 'guard'
423 | CLASS(_name, __UNIQUE_ID(guard))
| ^
include/linux/cleanup.h:303:3: note: expanded from macro 'CLASS'
303 | class_##_name##_constructor
| ^
<scratch space>:107:1: note: expanded from here
107 | class_mutex_constructor
| ^
4 errors generated.
vim +139 drivers/staging/iio/adc/ad7816.c
130
131 static ssize_t ad7816_store_mode(struct device *dev,
132 struct device_attribute *attr,
133 const char *buf,
134 size_t len)
135 {
136 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
137 struct ad7816_chip_info *chip = iio_priv(indio_dev);
138
> 139 guard(mutex)(&chip->lock);
140
141 if (strcmp(buf, "full") == 0) {
142 gpiod_set_value(chip->rdwr_pin, 1);
143 chip->mode = AD7816_FULL;
144 } else {
145 gpiod_set_value(chip->rdwr_pin, 0);
146 chip->mode = AD7816_PD;
147 }
148
149 return len;
150 }
151
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 4+ messages in thread