[PATCH 4.11 66/78] staging: iio: ad7152: Fix deadlock in ad7152_write_raw_samp_freq()

Greg Kroah-Hartman
2017-06-19T15:21:44Z

From: Alexey Khoroshilov <khoroshilov@ispras.ru>

commit 95264c8c6a9040e84edda883dbbe9d193c41f46c upstream.

ad7152_write_raw_samp_freq() is called by ad7152_write_raw() with
chip->state_lock held. So, there is unavoidable deadlock when
ad7152_write_raw_samp_freq() locks the mutex itself.

The patch removes unneeded locking.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Fixes: 6572389bcc11 ("staging: iio: cdc: ad7152: Implement IIO_CHAN_INFO_SAMP_FREQ attribute")
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/staging/iio/cdc/ad7152.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

--- a/drivers/staging/iio/cdc/ad7152.c
+++ b/drivers/staging/iio/cdc/ad7152.c
@@ -231,16 +231,12 @@ static int ad7152_write_raw_samp_freq(st
if (i >= ARRAY_SIZE(ad7152_filter_rate_table))
i = ARRAY_SIZE(ad7152_filter_rate_table) - 1;

- mutex_lock(&chip->state_lock);
ret = i2c_smbus_write_byte_data(chip->client,
AD7152_REG_CFG2, AD7152_CFG2_OSR(i));
- if (ret < 0) {
- mutex_unlock(&chip->state_lock);
+ if (ret < 0)
return ret;
- }

chip->filter_rate_setup = i;
- mutex_unlock(&chip->state_lock);

return ret;
}