* [PATCH] staging: iio: ad7152: Fix deadlock in ad7152_write_raw_samp_freq()
@ 2017-05-26 22:53 Alexey Khoroshilov
2017-05-28 9:47 ` Lars-Peter Clausen
0 siblings, 1 reply; 3+ messages in thread
From: Alexey Khoroshilov @ 2017-05-26 22:53 UTC (permalink / raw)
To: Lars-Peter Clausen, Michael Hennerich, Jonathan Cameron,
Hartmut Knaack, Peter Meerwald-Stadler, Greg Kroah-Hartman
Cc: Alexey Khoroshilov, linux-iio, devel, linux-kernel, ldv-project
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>
---
drivers/staging/iio/cdc/ad7152.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/drivers/staging/iio/cdc/ad7152.c b/drivers/staging/iio/cdc/ad7152.c
index dc6ecd824365..ff10d1f0a7e4 100644
--- 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(struct device *dev, int val)
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;
}
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] staging: iio: ad7152: Fix deadlock in ad7152_write_raw_samp_freq()
2017-05-26 22:53 [PATCH] staging: iio: ad7152: Fix deadlock in ad7152_write_raw_samp_freq() Alexey Khoroshilov
@ 2017-05-28 9:47 ` Lars-Peter Clausen
2017-05-28 14:46 ` Jonathan Cameron
0 siblings, 1 reply; 3+ messages in thread
From: Lars-Peter Clausen @ 2017-05-28 9:47 UTC (permalink / raw)
To: Alexey Khoroshilov, Michael Hennerich, Jonathan Cameron,
Hartmut Knaack, Peter Meerwald-Stadler, Greg Kroah-Hartman
Cc: linux-iio, devel, linux-kernel, ldv-project
On 05/27/2017 12:53 AM, Alexey Khoroshilov wrote:
> 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>
Looks good, thanks.
Fixes: 6572389bcc11 ("staging: iio: cdc: ad7152: Implement
IIO_CHAN_INFO_SAMP_FREQ attribute")
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
> ---
> drivers/staging/iio/cdc/ad7152.c | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/drivers/staging/iio/cdc/ad7152.c b/drivers/staging/iio/cdc/ad7152.c
> index dc6ecd824365..ff10d1f0a7e4 100644
> --- 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(struct device *dev, int val)
> 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;
> }
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] staging: iio: ad7152: Fix deadlock in ad7152_write_raw_samp_freq()
2017-05-28 9:47 ` Lars-Peter Clausen
@ 2017-05-28 14:46 ` Jonathan Cameron
0 siblings, 0 replies; 3+ messages in thread
From: Jonathan Cameron @ 2017-05-28 14:46 UTC (permalink / raw)
To: Lars-Peter Clausen
Cc: Alexey Khoroshilov, Michael Hennerich, Hartmut Knaack,
Peter Meerwald-Stadler, Greg Kroah-Hartman, linux-iio, devel,
linux-kernel, ldv-project
On Sun, 28 May 2017 11:47:04 +0200
Lars-Peter Clausen <lars@metafoo.de> wrote:
> On 05/27/2017 12:53 AM, Alexey Khoroshilov wrote:
> > 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>
>
> Looks good, thanks.
>
> Fixes: 6572389bcc11 ("staging: iio: cdc: ad7152: Implement
> IIO_CHAN_INFO_SAMP_FREQ attribute")
> Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Applied to the fixes-togreg branch of iio.git.
Thanks,
Jonathan
>
>
> > ---
> > drivers/staging/iio/cdc/ad7152.c | 6 +-----
> > 1 file changed, 1 insertion(+), 5 deletions(-)
> >
> > diff --git a/drivers/staging/iio/cdc/ad7152.c b/drivers/staging/iio/cdc/ad7152.c
> > index dc6ecd824365..ff10d1f0a7e4 100644
> > --- 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(struct device *dev, int val)
> > 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;
> > }
> >
>
> --
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2017-05-26 22:53 [PATCH] staging: iio: ad7152: Fix deadlock in ad7152_write_raw_samp_freq() Alexey Khoroshilov
2017-05-28 9:47 ` Lars-Peter Clausen
2017-05-28 14:46 ` Jonathan Cameron
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