Re: [PATCH v2] iio: stm32-dac: Replace indio_dev->mlock with own device lock

From: Alexandru Ardelean <ardeleanalex@gmail.com>
To: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: Alexandru Ardelean <alexandru.ardelean@analog.com>,
	linux-iio <linux-iio@vger.kernel.org>,
	linux-stm32@st-md-mailman.stormreply.com,
	LKML <linux-kernel@vger.kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	Jonathan Cameron <jic23@kernel.org>,
	alexandre.torgue@st.com,
	Sergiu Cuciurean <sergiu.cuciurean@analog.com>
Subject: Re: [PATCH v2] iio: stm32-dac: Replace indio_dev->mlock with own device lock
Date: Thu, 27 Aug 2020 13:00:36 +0300	[thread overview]
Message-ID: <CA+U=DspjGUhXCY7c8P6zOYZsx17ybcU4Kdr52yujmdYOaa1JSQ@mail.gmail.com> (raw)
In-Reply-To: <c3a9411e-186d-a3ac-5ad0-bd70ad78f147@st.com>

On Thu, Aug 27, 2020 at 12:03 PM Fabrice Gasnier <fabrice.gasnier@st.com> wrote:
>
> On 8/27/20 10:55 AM, Alexandru Ardelean wrote:
> > On Wed, Aug 26, 2020 at 3:03 PM Alexandru Ardelean
> > <alexandru.ardelean@analog.com> wrote:
> >> From: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> >>
> >> As part of the general cleanup of indio_dev->mlock, this change replaces
> >> it with a local lock. The lock protects against potential races when
> >> reading the CR reg and then updating, so that the state of pm_runtime
> >> is consistent between the two operations.
> >>
> >> Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> >> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
> >> ---
> > Forgot the changelog here.
> > Apologies.
> >
> > Changelog v1 -> v2:
> > * removed whitespace change for 'common' field
> > * updated comment about the lock usage
>
> Hi Alexandru,
>
> Sorry if I missed it... is there an update on the comment :-) ?

For a moment there, I thought I didn't.
GMail's threading is confusing.

----------------------------------------------------------------------------
As part of the general cleanup of indio_dev->mlock, this change replaces
it with a local lock. The lock protects against potential races when
reading the CR reg and then updating, so that the state of pm_runtime
is consistent between the two operations.
----------------------------------------------------------------------------

>
> Best Regards,
> Fabrice
> >
> >>  drivers/iio/dac/stm32-dac.c | 12 ++++++++----
> >>  1 file changed, 8 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/iio/dac/stm32-dac.c b/drivers/iio/dac/stm32-dac.c
> >> index 092c796fa3d9..7a8aed476850 100644
> >> --- a/drivers/iio/dac/stm32-dac.c
> >> +++ b/drivers/iio/dac/stm32-dac.c
> >> @@ -26,9 +26,11 @@
> >>  /**
> >>   * struct stm32_dac - private data of DAC driver
> >>   * @common:            reference to DAC common data
> >> + * @lock:              lock to protect the data buffer during regmap ops
> >>   */
> >>  struct stm32_dac {
> >>         struct stm32_dac_common *common;
> >> +       struct mutex            lock;
> >>  };