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From:   "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        Tsuchiya Yuto <kitakar@gmail.com>
Cc:     Sakari Ailus <sakari.ailus@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Martiros Shakhzadyan <vrzh@vrzh.net>,
        Hans de Goede <hdegoede@redhat.com>,
        linux-media@vger.kernel.org, linux-staging@lists.linux.dev,
        linux-kernel@vger.kernel.org, Ira Weiny <ira.weiny@intel.com>,
        outreachy@lists.linux.dev
Subject: Re: [PATCH] staging: media: atomisp: Use kmap_local_page() in hmm_store()
Date:   Fri, 29 Apr 2022 15:46:47 +0200
Message-ID: <3664993.kQq0lBPeGt@leap>
In-Reply-To: <2181693.iZASKD2KPV@leap>
References: <20220413225531.9425-1-fmdefrancesco@gmail.com> <2181693.iZASKD2KPV@leap>
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On luned=C3=AC 25 aprile 2022 20:29:03 CEST Fabio M. De Francesco wrote:
> On gioved=C3=AC 14 aprile 2022 00:55:31 CEST Fabio M. De Francesco wrote:
> > The use of kmap() is being deprecated in favor of kmap_local_page()
> > where it is feasible. The same is true for kmap_atomic().
> >=20
> > In file pci/hmm/hmm.c, function hmm_store() test if we are in atomic
> > context and, if so, it calls kmap_atomic(), if not, it calls kmap().
> >=20
> > First of all, in_atomic() shouldn't be used in drivers. This macro
> > cannot always detect atomic context; in particular, it cannot know
> > about held spinlocks in non-preemptible kernels.
> >=20
> > Notwithstanding what it is said above, this code doesn't need to care
> > whether or not it is executing in atomic context. It can simply use
> > kmap_local_page() / kunmap_local() that can instead do the mapping /
> > unmapping regardless of the context.
> >=20
> > With kmap_local_page(), the mapping is per thread, CPU local and not
> > globally visible. Therefore, hmm_store()() is a function where the use
> > of kmap_local_page() in place of both kmap() and kmap_atomic() is
> > correctly suited.
> >=20
> > Convert the calls of kmap() / kunmap() and kmap_atomic() /
> > kunmap_atomic() to kmap_local_page() / kunmap_local() and drop the
> > unnecessary tests which test if the code is in atomic context.
> >=20
> > Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
> > ---
> >  drivers/staging/media/atomisp/pci/hmm/hmm.c | 14 ++------------
> >  1 file changed, 2 insertions(+), 12 deletions(-)
>=20
> Hi Mauro,
>=20
> I'm writing for just a gentle ping for this and two other staging/
atomisp/=20
> patches that still seem to be waiting to be applied.
>=20
> In the meantime I would like to remind you that Hans de Goede has=20
> successfully tested this patch and the other two on both the front and=20
back=20
> cams of a chuwi hi8 tablet.

Hi Mauro,

In my previous message I forgot to remind you that two of these three=20
patches have also been reviewed by Ira Weiny (Intel).

I'd like to ask you again if there is still something left which prevents=20
these three patches from being accepted. The first of the three patches was=
=20
submitted on April 9, 2022.

=46or you convenience here are the links to the patches, the "Reviewed-by:"=
=20
and "Tested-by:" tags:

[PATCH] staging: media: atomisp: Use kmap_local_page() in hmm_store()
https://lore.kernel.org/lkml/20220413225531.9425-1-fmdefrancesco@gmail.com/
https://lore.kernel.org/lkml/Yli+R7iLZKqO8kVP@iweiny-desk3/
https://lore.kernel.org/lkml/2d096f20-dbaa-1d49-96e9-a7ae6c19f7fe@redhat.co=
m/

[PATCH] staging: media: atomisp: Use kmap_local_page() in hmm_set()
https://lore.kernel.org/lkml/20220413212210.18494-1-fmdefrancesco@gmail.com/
https://lore.kernel.org/lkml/YldNhErgt53RqYp7@iweiny-desk3/
https://lore.kernel.org/lkml/0b04ad1a-e442-1728-ef2c-bab386a4c64c@redhat.co=
m/

[PATCH] staging: media: atomisp: Convert kmap() to kmap_local_page()
https://lore.kernel.org/lkml/20220408223129.3844-1-fmdefrancesco@gmail.com/
https://lore.kernel.org/lkml/b0aed731-b56f-4378-b50e-fc0cbccbdb84@redhat.co=
m/

Thanks,

=46abio M. De Francesco

P.S.: Do you want me to resend them all and add the above-mentioned tags?