From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Alexandru Ardelean <alexandru.ardelean@analog.com>
Cc: linux-iio <linux-iio@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jonathan Cameron <jic23@kernel.org>,
Lars-Peter Clausen <lars@metafoo.de>,
Hartmut Knaack <knaack.h@gmx.de>,
Peter Meerwald <pmeerw@pmeerw.ne>
Subject: Re: [PATCH v2] iio: buffer: Don't allow buffers without any channels enabled to be activated
Date: Wed, 25 Mar 2020 17:57:50 +0200 [thread overview]
Message-ID: <CAHp75VfVggWZ6WhOa=nUrxyd0dJrTbZd9NnUMhQ_S=kncrAhOw@mail.gmail.com> (raw)
In-Reply-To: <20200325100112.85107-1-alexandru.ardelean@analog.com>
On Wed, Mar 25, 2020 at 12:02 PM Alexandru Ardelean
<alexandru.ardelean@analog.com> wrote:
>
> From: Lars-Peter Clausen <lars@metafoo.de>
>
> 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 <lars@metafoo.de>
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
> ---
>
> 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
next prev parent reply other threads:[~2020-03-25 15:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200320104031.31701-1-alexandru.ardelean@analog.com>
2020-03-25 10:01 ` [PATCH v2] iio: buffer: Don't allow buffers without any channels enabled to be activated Alexandru Ardelean
2020-03-25 10:12 ` Ardelean, Alexandru
2020-03-25 15:57 ` Andy Shevchenko [this message]
2020-03-26 7:42 ` Ardelean, Alexandru
2020-03-26 7:44 ` Lars-Peter Clausen
2020-03-26 7:46 ` Ardelean, Alexandru
2020-03-26 9:30 ` [PATCH v3] " Alexandru Ardelean
2020-03-28 13:13 ` Jonathan Cameron
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