From: Alexandru Ardelean <email@example.com> To: Krzysztof Kozlowski <firstname.lastname@example.org> Cc: Alexandru Ardelean <email@example.com>, linux-iio <firstname.lastname@example.org>, LKML <email@example.com>, Jonathan Cameron <firstname.lastname@example.org>, email@example.com, Sergiu Cuciurean <firstname.lastname@example.org> Subject: Re: [PATCH] iio: adc: exynos_adc: Replace indio_dev->mlock with own device lock Date: Thu, 27 Aug 2020 11:53:44 +0300 [thread overview] Message-ID: <CA+U=Dsoo6YABe5ODLp+eFNPGFDjk5ZeQEceGkqjxXcVEhLWubw@mail.gmail.com> (raw) In-Reply-To: <20200827065625.GB17964@kozik-lap> On Thu, Aug 27, 2020 at 9:57 AM Krzysztof Kozlowski <email@example.com> wrote: > > On Wed, Aug 26, 2020 at 04:22:03PM +0300, Alexandru Ardelean wrote: > > From: Sergiu Cuciurean <firstname.lastname@example.org> > > > > As part of the general cleanup of indio_dev->mlock, this change replaces > > it with a local lock, to protect potential concurrent access to the > > completion callback during a conversion. > > I don't know the bigger picture (and no links here for general cleanup) > but I assume it is part of wider work and that mlock is unwanted. In > such case: > > Reviewed-by: Krzysztof Kozlowski <email@example.com> > > If it is part of some bigger work, please put a link to lore.kernel.org > under separators ---, so everyone can get the context. Will keep that in mind. I am not sure if there is a lore.kernel.org link that's easy to find for a discussion on this topic, maybe I can describe it here and use the link [from this later]. This was something that popped up during reviews we got from Jonathan [or others], saying "please don't use indio_dev->mlock, that is an IIO framework lock, and an IIO driver should not use it". Reasons include [and some may be repeated a bit]: - this could cause a deadlock if the IIO framework holds this lock and an IIO driver also tries to get a hold of this lock - similar to the previous point, this mlock is taken by iio_device_claim_direct_mode() and released by iio_device_release_direct_mode() ; which means that mlock aims to become more of an IIO framework lock, than a general usage lock; - this wasn't policed/reviewed intensely in the older driver [a few years ago], but has become a point in recent reviews; - if we want to develop/enhance the IIO framework, some elements like this need to be taken care of, as more drivers get added and more complexity gets added; - there is an element of fairness [obviously], where someone writing a new IIO driver, takes an older one as example, and gets hit on the review; the person feels they did a good job in mimicking the old driver; their feeling is correct; the IIO framework should provide good references and/or cleanup existing drivers; - same as the previous point, we don't want to keep telling people writing new IIO drivers [and starting out with IIO] to "not use mlock [because it was copied from an old driver]"; it's more/needless review work > > > Best regards, > Krzysztof > > > > > Signed-off-by: Sergiu Cuciurean <firstname.lastname@example.org> > > Signed-off-by: Alexandru Ardelean <email@example.com> > > --- > > drivers/iio/adc/exynos_adc.c | 12 ++++++++---- > > 1 file changed, 8 insertions(+), 4 deletions(-) > >
next prev parent reply other threads:[~2020-08-27 8:53 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-08-26 13:22 Alexandru Ardelean 2020-08-27 6:56 ` Krzysztof Kozlowski 2020-08-27 8:53 ` Alexandru Ardelean [this message] 2020-08-29 15:33 ` Jonathan Cameron 2020-08-29 15:35 ` Jonathan Cameron 2020-09-16 9:31 ` [PATCH v2] " Alexandru Ardelean 2020-09-19 15:19 ` Jonathan Cameron
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