2020-03-25 10:02:44

by Alexandru Ardelean

Subject: [PATCH v2] iio: buffer: Don't allow buffers without any channels enabled to be activated

From: Lars-Peter Clausen <[email protected]>

Before activating a buffer make sure that at least one channel is enabled.
Activating a buffer with 0 channels enabled doesn't make too much sense and
disallowing this case makes sure that individual driver don't have to add
special case code to handle it.

Currently, without this patch enabling a buffer is possible and no error is
produced. With this patch -EINVAL is returned.

An example of execution with this patch and some instrumented print-code:
root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer->scan_mask 00000000
1: iio_verify_update 753
2:__iio_update_buffers 1115 ret -22
3: iio_buffer_store_enable 1241 ret -22
-bash: echo: write error: Invalid argument
1, 2 & 3 are exit-error paths. 0 the first print in iio_verify_update()
rergardless of error path.

Without this patch (and same instrumented print-code):
root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer->scan_mask 00000000
root@analog:/sys/bus/iio/devices/iio:device3/buffer#
Buffer is enabled with no error.

Signed-off-by: Lars-Peter Clausen <[email protected]>
Signed-off-by: Alexandru Ardelean <[email protected]>
---

Changelog v1 -> v2:
* moved check in iio_verify_update()
* added dev_dbg() message; should help some folks understand the message
* documented steps to reproduce
* added Fixes tag; hopefully the tag is the good one; if needed, it can be
  dropped; this has been around for ~8 years; no idea if it's worth
  backporting

drivers/iio/industrialio-buffer.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 5ff34ce8b6a2..e6fa1a4e135d 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -686,6 +686,13 @@ static int iio_verify_update(struct iio_dev *indio_dev,
bool scan_timestamp;
unsigned int modes;

+ if (insert_buffer &&
+ bitmap_empty(insert_buffer->scan_mask, indio_dev->masklength)) {
+ dev_dbg(&indio_dev->dev,
+ "At least one scan element must be enabled first\n");
+ return -EINVAL;
+ }
+
memset(config, 0, sizeof(*config));
config->watermark = ~0;

--
2.17.1

2020-03-25 10:14:25

by Alexandru Ardelean

Subject: Re: [PATCH v2] iio: buffer: Don't allow buffers without any channels enabled to be activated

On Wed, 2020-03-25 at 12:01 +0200, Alexandru Ardelean wrote:
> From: Lars-Peter Clausen <[email protected]>
>
> Before activating a buffer make sure that at least one channel is enabled.
> Activating a buffer with 0 channels enabled doesn't make too much sense and
> disallowing this case makes sure that individual driver don't have to add
> special case code to handle it.
>

oops, i goof-ed peter's email on this send;
[ copy + paste err ]
should be fixed now;

> Currently, without this patch enabling a buffer is possible and no error is
> produced. With this patch -EINVAL is returned.
>
> An example of execution with this patch and some instrumented print-code:
> root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
> root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
> 0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer->scan_mask
> 00000000
> 1: iio_verify_update 753
> 2:__iio_update_buffers 1115 ret -22
> 3: iio_buffer_store_enable 1241 ret -22
> -bash: echo: write error: Invalid argument
> 1, 2 & 3 are exit-error paths. 0 the first print in iio_verify_update()
> rergardless of error path.
>
> Without this patch (and same instrumented print-code):
> root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
> root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
> 0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer->scan_mask
> 00000000
> root@analog:/sys/bus/iio/devices/iio:device3/buffer#
> Buffer is enabled with no error.
>
> Signed-off-by: Lars-Peter Clausen <[email protected]>
> Signed-off-by: Alexandru Ardelean <[email protected]>
> ---
>
> Changelog v1 -> v2:
> * moved check in iio_verify_update()
> * added dev_dbg() message; should help some folks understand the message
> * documented steps to reproduce
> * added Fixes tag; hopefully the tag is the good one; if needed, it can be
> dropped; this has been around for ~8 years; no idea if it's worth
> backporting
>
> drivers/iio/industrialio-buffer.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-
> buffer.c
> index 5ff34ce8b6a2..e6fa1a4e135d 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -686,6 +686,13 @@ static int iio_verify_update(struct iio_dev *indio_dev,
> bool scan_timestamp;
> unsigned int modes;
>
> + if (insert_buffer &&
> + bitmap_empty(insert_buffer->scan_mask, indio_dev->masklength)) {
> + dev_dbg(&indio_dev->dev,
> + "At least one scan element must be enabled first\n");
> + return -EINVAL;
> + }
> +
> memset(config, 0, sizeof(*config));
> config->watermark = ~0;
>

2020-03-25 15:58:44

by Andy Shevchenko

Subject: Re: [PATCH v2] iio: buffer: Don't allow buffers without any channels enabled to be activated

On Wed, Mar 25, 2020 at 12:02 PM Alexandru Ardelean
<[email protected]> wrote:
>
> From: Lars-Peter Clausen <[email protected]>
>
> Before activating a buffer make sure that at least one channel is enabled.
> Activating a buffer with 0 channels enabled doesn't make too much sense and
> disallowing this case makes sure that individual driver don't have to add
> special case code to handle it.
>
> Currently, without this patch enabling a buffer is possible and no error is
> produced. With this patch -EINVAL is returned.
>
> An example of execution with this patch and some instrumented print-code:
> root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
> root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
> 0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer->scan_mask 00000000
> 1: iio_verify_update 753
> 2:__iio_update_buffers 1115 ret -22
> 3: iio_buffer_store_enable 1241 ret -22
> -bash: echo: write error: Invalid argument
> 1, 2 & 3 are exit-error paths. 0 the first print in iio_verify_update()
> rergardless of error path.
>
> Without this patch (and same instrumented print-code):
> root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
> root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
> 0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer->scan_mask 00000000
> root@analog:/sys/bus/iio/devices/iio:device3/buffer#
> Buffer is enabled with no error.
>
> Signed-off-by: Lars-Peter Clausen <[email protected]>
> Signed-off-by: Alexandru Ardelean <[email protected]>
> ---
>
> Changelog v1 -> v2:
> * moved check in iio_verify_update()
> * added dev_dbg() message; should help some folks understand the message
> * documented steps to reproduce

> * added Fixes tag; hopefully the tag is the good one; if needed, it can be
> dropped; this has been around for ~8 years; no idea if it's worth
> backporting

Where?

>
> drivers/iio/industrialio-buffer.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> index 5ff34ce8b6a2..e6fa1a4e135d 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -686,6 +686,13 @@ static int iio_verify_update(struct iio_dev *indio_dev,
> bool scan_timestamp;
> unsigned int modes;
>
> + if (insert_buffer &&
> + bitmap_empty(insert_buffer->scan_mask, indio_dev->masklength)) {
> + dev_dbg(&indio_dev->dev,
> + "At least one scan element must be enabled first\n");
> + return -EINVAL;
> + }
> +
> memset(config, 0, sizeof(*config));
> config->watermark = ~0;
>
> --
> 2.17.1
>


--
With Best Regards,
Andy Shevchenko

2020-03-26 07:44:03

by Alexandru Ardelean

Subject: Re: [PATCH v2] iio: buffer: Don't allow buffers without any channels enabled to be activated

On Wed, 2020-03-25 at 17:57 +0200, Andy Shevchenko wrote:
> [External]
>
> On Wed, Mar 25, 2020 at 12:02 PM Alexandru Ardelean
> <[email protected]> wrote:
> > From: Lars-Peter Clausen <[email protected]>
> >
> > Before activating a buffer make sure that at least one channel is enabled.
> > Activating a buffer with 0 channels enabled doesn't make too much sense and
> > disallowing this case makes sure that individual driver don't have to add
> > special case code to handle it.
> >
> > Currently, without this patch enabling a buffer is possible and no error is
> > produced. With this patch -EINVAL is returned.
> >
> > An example of execution with this patch and some instrumented print-code:
> > root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
> > root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
> > 0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer-
> > >scan_mask 00000000
> > 1: iio_verify_update 753
> > 2:__iio_update_buffers 1115 ret -22
> > 3: iio_buffer_store_enable 1241 ret -22
> > -bash: echo: write error: Invalid argument
> > 1, 2 & 3 are exit-error paths. 0 the first print in iio_verify_update()
> > rergardless of error path.
> >
> > Without this patch (and same instrumented print-code):
> > root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
> > root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
> > 0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer-
> > >scan_mask 00000000
> > root@analog:/sys/bus/iio/devices/iio:device3/buffer#
> > Buffer is enabled with no error.
> >
> > Signed-off-by: Lars-Peter Clausen <[email protected]>
> > Signed-off-by: Alexandru Ardelean <[email protected]>
> > ---
> >
> > Changelog v1 -> v2:
> > * moved check in iio_verify_update()
> > * added dev_dbg() message; should help some folks understand the message
> > * documented steps to reproduce
> > * added Fixes tag; hopefully the tag is the good one; if needed, it can be
> > dropped; this has been around for ~8 years; no idea if it's worth
> > backporting
>
> Where?

stable/fixes/lts-kernels
don't have a really good clue about where these things need backporting;

>
> > drivers/iio/industrialio-buffer.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-
> > buffer.c
> > index 5ff34ce8b6a2..e6fa1a4e135d 100644
> > --- a/drivers/iio/industrialio-buffer.c
> > +++ b/drivers/iio/industrialio-buffer.c
> > @@ -686,6 +686,13 @@ static int iio_verify_update(struct iio_dev *indio_dev,
> > bool scan_timestamp;
> > unsigned int modes;
> >
> > + if (insert_buffer &&
> > + bitmap_empty(insert_buffer->scan_mask, indio_dev->masklength)) {
> > + dev_dbg(&indio_dev->dev,
> > + "At least one scan element must be enabled
> > first\n");
> > + return -EINVAL;
> > + }
> > +
> > memset(config, 0, sizeof(*config));
> > config->watermark = ~0;
> >
> > --
> > 2.17.1
> >
>
>

2020-03-26 07:45:14

by Lars-Peter Clausen

Subject: Re: [PATCH v2] iio: buffer: Don't allow buffers without any channels enabled to be activated

On 3/26/20 8:42 AM, Ardelean, Alexandru wrote:
> On Wed, 2020-03-25 at 17:57 +0200, Andy Shevchenko wrote:
>> [External]
>>
>> On Wed, Mar 25, 2020 at 12:02 PM Alexandru Ardelean
>> <[email protected]> wrote:
>>> From: Lars-Peter Clausen <[email protected]>
>>>
>>> Before activating a buffer make sure that at least one channel is enabled.
>>> Activating a buffer with 0 channels enabled doesn't make too much sense and
>>> disallowing this case makes sure that individual driver don't have to add
>>> special case code to handle it.
>>>
>>> Currently, without this patch enabling a buffer is possible and no error is
>>> produced. With this patch -EINVAL is returned.
>>>
>>> An example of execution with this patch and some instrumented print-code:
>>> root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
>>> root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
>>> 0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer-
>>>> scan_mask 00000000
>>> 1: iio_verify_update 753
>>> 2:__iio_update_buffers 1115 ret -22
>>> 3: iio_buffer_store_enable 1241 ret -22
>>> -bash: echo: write error: Invalid argument
>>> 1, 2 & 3 are exit-error paths. 0 the first print in iio_verify_update()
>>> rergardless of error path.
>>>
>>> Without this patch (and same instrumented print-code):
>>> root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
>>> root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
>>> 0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer-
>>>> scan_mask 00000000
>>> root@analog:/sys/bus/iio/devices/iio:device3/buffer#
>>> Buffer is enabled with no error.
>>>
>>> Signed-off-by: Lars-Peter Clausen <[email protected]>
>>> Signed-off-by: Alexandru Ardelean <[email protected]>
>>> ---
>>>
>>> Changelog v1 -> v2:
>>> * moved check in iio_verify_update()
>>> * added dev_dbg() message; should help some folks understand the message
>>> * documented steps to reproduce
>>> * added Fixes tag; hopefully the tag is the good one; if needed, it can be
>>> dropped; this has been around for ~8 years; no idea if it's worth
>>> backporting
>> Where?
> stable/fixes/lts-kernels
> don't have a really good clue about where these things need backporting;
What Andy means is that there is no Fixes tag :)

2020-03-26 07:48:42

by Alexandru Ardelean

Subject: Re: [PATCH v2] iio: buffer: Don't allow buffers without any channels enabled to be activated

On Thu, 2020-03-26 at 08:44 +0100, Lars-Peter Clausen wrote:
> [External]
>
> On 3/26/20 8:42 AM, Ardelean, Alexandru wrote:
> > On Wed, 2020-03-25 at 17:57 +0200, Andy Shevchenko wrote:
> > > [External]
> > >
> > > On Wed, Mar 25, 2020 at 12:02 PM Alexandru Ardelean
> > > <[email protected]> wrote:
> > > > From: Lars-Peter Clausen <[email protected]>
> > > >
> > > > Before activating a buffer make sure that at least one channel is
> > > > enabled.
> > > > Activating a buffer with 0 channels enabled doesn't make too much sense
> > > > and
> > > > disallowing this case makes sure that individual driver don't have to
> > > > add
> > > > special case code to handle it.
> > > >
> > > > Currently, without this patch enabling a buffer is possible and no error
> > > > is
> > > > produced. With this patch -EINVAL is returned.
> > > >
> > > > An example of execution with this patch and some instrumented print-
> > > > code:
> > > > root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
> > > > root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
> > > > 0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer-
> > > > > scan_mask 00000000
> > > > 1: iio_verify_update 753
> > > > 2:__iio_update_buffers 1115 ret -22
> > > > 3: iio_buffer_store_enable 1241 ret -22
> > > > -bash: echo: write error: Invalid argument
> > > > 1, 2 & 3 are exit-error paths. 0 the first print in iio_verify_update()
> > > > rergardless of error path.
> > > >
> > > > Without this patch (and same instrumented print-code):
> > > > root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
> > > > root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
> > > > 0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer-
> > > > > scan_mask 00000000
> > > > root@analog:/sys/bus/iio/devices/iio:device3/buffer#
> > > > Buffer is enabled with no error.
> > > >
> > > > Signed-off-by: Lars-Peter Clausen <[email protected]>
> > > > Signed-off-by: Alexandru Ardelean <[email protected]>
> > > > ---
> > > >
> > > > Changelog v1 -> v2:
> > > > * moved check in iio_verify_update()
> > > > * added dev_dbg() message; should help some folks understand the message
> > > > * documented steps to reproduce
> > > > * added Fixes tag; hopefully the tag is the good one; if needed, it can
> > > > be
> > > > dropped; this has been around for ~8 years; no idea if it's worth
> > > > backporting
> > > Where?
> > stable/fixes/lts-kernels
> > don't have a really good clue about where these things need backporting;
> What Andy means is that there is no Fixes tag :)

oh crap....
i added one but seem to have lost it when moving the patch to the server from
where i do git-send
i'll add one;