From: Julia Lawall <julia.lawall@inria.fr>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Roland Dreier <roland@kernel.org>,
Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
ksummit@lists.linux.dev
Subject: Re: [TECH TOPIC] Rust for Linux
Date: Wed, 7 Jul 2021 09:27:32 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.22.394.2107070926370.6285@hadrien> (raw)
In-Reply-To: <YOTSYy2J2COzOY9l@pendragon.ideasonboard.com>
On Wed, 7 Jul 2021, Laurent Pinchart wrote:
> On Tue, Jul 06, 2021 at 10:36:14PM +0200, Linus Walleij wrote:
> > On Tue, Jul 6, 2021 at 10:00 PM Roland Dreier wrote:
> >
> > > One area I see where Rust could make a big improvement for drivers is
> > > in using RAII for error paths. Drivers often have a lot of code like
> > >
> > > if (something())
> > > return err;
> > >
> > > if (something_else())
> > > goto undo_something;
> > >
> > > if (a_third_thing())
> > > goto undo_two_things;
> > >
> > > and so on, which is difficult to get right in the first place and even
> > > harder to keep correct in the face of changes.
> >
> > Yes.
> >
> > > "devres" / devm_xxx was an attempt to deal with this in C, but it only
> > > solves some cases of this and has not received a lot of adoption (we
> > > can argue about the reasons).
> >
> > Really? From my point of view that is adopted all over the map.
> > I add new users all the time and use it as much as I can when
> > writing new drivers.
> >
> > $ git grep devm_ | wc -l
> > 26112
> >
> > Dmitry in the input subsystem even insist to use it for e.g. powering
> > down and disabling regulators on remove(), like recently in
> > drivers/input/touchscreen/cy8ctma140.c
> >
> > /* Called from the registered devm action */
> > static void cy8ctma140_power_off_action(void *d)
> > {
> > struct cy8ctma140 *ts = d;
> >
> > cy8ctma140_power_down(ts);
> > }
> > (...)
> > error = devm_add_action_or_reset(dev, cy8ctma140_power_off_action, ts);
> > if (error) {
> > dev_err(dev, "failed to install power off handler\n");
> > return error;
> > }
> >
> > I think it's a formidable success, people just need to learn to do it more.
>
> devres is interesting and has good use cases, but the devm_k*alloc() are
> a nightmare. They're used through drivers without any consideration of
> life time management of the allocated memory, to allocate data
> structures that can be accessed in userspace-controlled code paths.
> Open a device node, keep it open, unplug the device, close the device
> node, and in many cases you'll find that the kernel can crash :-( When
> the first line of the probe function of a driver that exposes a chardev
> if a devm_kzalloc(), it's usually a sign that something is wrong.
Where should the free have been? Will Rust help in this case? Will it
result in a memory leak?
julia
>
> I wonder if we could also benefit from the gcc cleanup attribute
> (https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-cleanup-variable-attribute).
> I don't know if it's supported by the other compilers we care about
> though.
>
> > But if an easier path to learn better behaviours is to shuffle the whole
> > chessboard and replace it with drivers written in Rust, I don't know?
> > Maybe?
>
> --
> Regards,
>
> Laurent Pinchart
>
>
next prev parent reply other threads:[~2021-07-07 7:28 UTC|newest]
Thread overview: 201+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-25 22:09 [TECH TOPIC] Rust for Linux Miguel Ojeda
2021-07-05 23:51 ` Linus Walleij
2021-07-06 4:30 ` Leon Romanovsky
2021-07-06 9:55 ` Linus Walleij
2021-07-06 10:16 ` Geert Uytterhoeven
2021-07-06 17:59 ` Linus Walleij
2021-07-06 18:36 ` Miguel Ojeda
2021-07-06 19:12 ` Linus Walleij
2021-07-06 21:32 ` Miguel Ojeda
2021-07-07 14:10 ` Arnd Bergmann
2021-07-07 15:28 ` Miguel Ojeda
2021-07-07 15:50 ` Andrew Lunn
2021-07-07 16:34 ` Miguel Ojeda
2021-07-07 16:55 ` Arnd Bergmann
2021-07-07 17:54 ` Miguel Ojeda
2021-07-06 10:22 ` Leon Romanovsky
2021-07-06 14:30 ` Miguel Ojeda
2021-07-06 14:32 ` Miguel Ojeda
2021-07-06 15:03 ` Sasha Levin
2021-07-06 15:33 ` Miguel Ojeda
2021-07-06 15:42 ` Laurent Pinchart
2021-07-06 16:09 ` Mike Rapoport
2021-07-06 18:29 ` Miguel Ojeda
2021-07-06 18:38 ` Laurent Pinchart
2021-07-06 19:45 ` Steven Rostedt
2021-07-06 19:59 ` Miguel Ojeda
2021-07-06 18:53 ` Sasha Levin
2021-07-06 21:50 ` Miguel Ojeda
2021-07-07 4:57 ` Leon Romanovsky
2021-07-07 13:39 ` Alexandre Belloni
2021-07-07 13:50 ` Miguel Ojeda
2021-07-06 18:26 ` Linus Walleij
2021-07-06 19:11 ` Miguel Ojeda
2021-07-06 19:13 ` Johannes Berg
2021-07-06 19:43 ` Miguel Ojeda
2021-07-06 10:20 ` James Bottomley
2021-07-06 14:55 ` Miguel Ojeda
2021-07-06 15:01 ` Sasha Levin
2021-07-06 15:36 ` Miguel Ojeda
2021-07-09 10:02 ` Marco Elver
2021-07-09 16:02 ` Miguel Ojeda
2021-07-06 18:09 ` Linus Walleij
2021-07-06 14:24 ` Miguel Ojeda
2021-07-06 14:33 ` Laurent Pinchart
2021-07-06 14:56 ` Leon Romanovsky
2021-07-06 15:29 ` Miguel Ojeda
2021-07-07 4:38 ` Leon Romanovsky
2021-07-06 20:00 ` Roland Dreier
2021-07-06 20:36 ` Linus Walleij
2021-07-06 22:00 ` Laurent Pinchart
2021-07-07 7:27 ` Julia Lawall [this message]
2021-07-07 7:45 ` Greg KH
2021-07-07 7:52 ` James Bottomley
2021-07-07 13:49 ` Miguel Ojeda
2021-07-07 14:08 ` James Bottomley
2021-07-07 15:15 ` Miguel Ojeda
2021-07-07 15:44 ` Greg KH
2021-07-07 17:01 ` Wedson Almeida Filho
2021-07-07 17:20 ` Greg KH
2021-07-07 19:19 ` Wedson Almeida Filho
2021-07-07 20:38 ` Jan Kara
2021-07-07 23:09 ` Wedson Almeida Filho
2021-07-08 6:11 ` Greg KH
2021-07-08 13:36 ` Wedson Almeida Filho
2021-07-08 18:51 ` Greg KH
2021-07-08 19:31 ` Andy Lutomirski
2021-07-08 19:35 ` Geert Uytterhoeven
2021-07-08 21:56 ` Andy Lutomirski
2021-07-08 19:49 ` Linus Walleij
2021-07-08 20:34 ` Miguel Ojeda
2021-07-08 22:13 ` Linus Walleij
2021-07-09 7:24 ` Geert Uytterhoeven
2021-07-19 12:24 ` Wedson Almeida Filho
2021-07-19 13:15 ` Wedson Almeida Filho
2021-07-19 14:02 ` Arnd Bergmann
2021-07-19 14:13 ` Linus Walleij
2021-07-19 21:32 ` Arnd Bergmann
2021-07-19 21:33 ` Arnd Bergmann
2021-07-20 1:46 ` Miguel Ojeda
2021-07-20 6:43 ` Johannes Berg
2021-07-19 14:43 ` Geert Uytterhoeven
2021-07-19 18:24 ` Miguel Ojeda
2021-07-19 18:47 ` Steven Rostedt
2021-07-19 14:54 ` Miguel Ojeda
2021-07-19 17:32 ` Wedson Almeida Filho
2021-07-19 21:31 ` Arnd Bergmann
2021-07-19 17:37 ` Miguel Ojeda
2021-07-19 16:02 ` Vegard Nossum
2021-07-19 17:45 ` Miguel Ojeda
2021-07-19 17:54 ` Miguel Ojeda
2021-07-19 18:06 ` Wedson Almeida Filho
2021-07-19 19:37 ` Laurent Pinchart
2021-07-19 21:09 ` Wedson Almeida Filho
2021-07-20 23:54 ` Laurent Pinchart
2021-07-21 1:33 ` Andy Lutomirski
2021-07-21 1:42 ` Laurent Pinchart
2021-07-21 13:54 ` Linus Walleij
2021-07-21 14:13 ` Wedson Almeida Filho
2021-07-21 14:19 ` Linus Walleij
2021-07-22 11:33 ` Wedson Almeida Filho
2021-07-23 0:45 ` Linus Walleij
2021-07-21 4:39 ` Wedson Almeida Filho
2021-07-23 1:04 ` Laurent Pinchart
2021-07-21 4:23 ` Wedson Almeida Filho
2021-07-23 1:13 ` Laurent Pinchart
2021-07-19 22:57 ` Alexandre Belloni
2021-07-20 7:15 ` Miguel Ojeda
2021-07-20 9:39 ` Alexandre Belloni
2021-07-20 12:10 ` Miguel Ojeda
2021-07-19 13:53 ` Linus Walleij
2021-07-19 14:42 ` Wedson Almeida Filho
2021-07-19 22:16 ` Linus Walleij
2021-07-20 1:20 ` Wedson Almeida Filho
2021-07-20 13:21 ` Andrew Lunn
2021-07-20 13:38 ` Miguel Ojeda
2021-07-20 14:04 ` Andrew Lunn
2021-07-20 13:55 ` Greg KH
2021-07-20 1:21 ` Miguel Ojeda
2021-07-20 16:00 ` Mark Brown
2021-07-20 22:42 ` Linus Walleij
2021-07-19 14:43 ` Miguel Ojeda
2021-07-19 15:15 ` Andrew Lunn
2021-07-19 15:43 ` Miguel Ojeda
2021-07-09 7:03 ` Viresh Kumar
2021-07-09 17:06 ` Mark Brown
2021-07-09 17:43 ` Miguel Ojeda
2021-07-10 9:53 ` Jonathan Cameron
2021-07-10 20:09 ` Kees Cook
2021-07-08 13:55 ` Miguel Ojeda
2021-07-08 14:58 ` Greg KH
2021-07-08 15:02 ` Mark Brown
2021-07-08 16:38 ` Andy Lutomirski
2021-07-08 18:01 ` Greg KH
2021-07-08 18:00 ` Miguel Ojeda
2021-07-08 18:44 ` Greg KH
2021-07-08 23:09 ` Miguel Ojeda
2021-07-08 7:20 ` Geert Uytterhoeven
2021-07-08 13:41 ` Wedson Almeida Filho
2021-07-08 13:43 ` Geert Uytterhoeven
2021-07-08 13:54 ` Wedson Almeida Filho
2021-07-08 14:16 ` Geert Uytterhoeven
2021-07-08 14:24 ` Wedson Almeida Filho
2021-07-09 7:04 ` Jerome Glisse
2021-07-08 14:04 ` Miguel Ojeda
2021-07-08 14:18 ` Geert Uytterhoeven
2021-07-08 14:28 ` Miguel Ojeda
2021-07-08 14:33 ` Geert Uytterhoeven
2021-07-08 14:35 ` Miguel Ojeda
2021-07-09 11:55 ` Geert Uytterhoeven
2021-07-08 16:07 ` Andy Lutomirski
2021-07-07 20:58 ` Miguel Ojeda
2021-07-07 21:47 ` Laurent Pinchart
2021-07-07 22:44 ` Miguel Ojeda
2021-07-07 17:01 ` Miguel Ojeda
2021-07-07 10:50 ` Mark Brown
2021-07-07 10:56 ` Julia Lawall
2021-07-07 11:27 ` James Bottomley
2021-07-07 11:34 ` James Bottomley
2021-07-07 12:20 ` Greg KH
2021-07-07 12:38 ` James Bottomley
2021-07-07 12:45 ` Greg KH
2021-07-07 17:17 ` Laurent Pinchart
2021-07-08 6:49 ` cdev/devm_* issues (was Re: [TECH TOPIC] Rust for Linux) Greg KH
2021-07-08 8:23 ` Laurent Pinchart
2021-07-08 23:06 ` Linus Walleij
2021-07-09 0:02 ` Dan Williams
2021-07-09 16:53 ` Wedson Almeida Filho
2021-07-13 8:59 ` Linus Walleij
[not found] ` <CAHp75VfW7PxAyU=eYPNWFU_oUY=aStz-4W5gX87KSo402YhMXQ@mail.gmail.com>
2021-07-21 13:46 ` Linus Walleij
2021-07-21 15:49 ` Andy Shevchenko
2021-07-10 7:09 ` Dan Carpenter
2021-07-12 13:42 ` Jason Gunthorpe
2021-07-15 9:54 ` Daniel Vetter
2021-07-21 9:08 ` Dan Carpenter
2021-07-22 9:56 ` Daniel Vetter
2021-07-22 10:09 ` Dan Carpenter
2021-07-08 9:08 ` [TECH TOPIC] Rust for Linux Mauro Carvalho Chehab
2021-07-10 16:42 ` Laurent Pinchart
2021-07-10 17:18 ` Andy Lutomirski
2021-07-07 15:17 ` Mark Brown
2021-07-06 21:45 ` Bart Van Assche
2021-07-06 23:08 ` Stephen Hemminger
2021-07-07 2:41 ` Bart Van Assche
2021-07-07 18:57 ` Linus Torvalds
2021-07-07 20:32 ` Bart Van Assche
2021-07-07 20:39 ` Linus Torvalds
2021-07-07 21:40 ` Laurent Pinchart
2021-07-08 7:22 ` Geert Uytterhoeven
2021-07-07 21:02 ` Laurent Pinchart
2021-07-07 22:11 ` Miguel Ojeda
2021-07-07 22:43 ` Laurent Pinchart
2021-07-07 23:21 ` Miguel Ojeda
2021-07-07 23:40 ` Laurent Pinchart
2021-07-08 0:27 ` Miguel Ojeda
2021-07-08 0:56 ` Laurent Pinchart
2021-07-08 6:26 ` Alexey Dobriyan
2021-07-06 19:05 ` Bart Van Assche
2021-07-06 19:27 ` Miguel Ojeda
2021-07-07 15:48 ` Steven Rostedt
2021-07-07 16:44 ` Miguel Ojeda
2023-08-07 10:03 Miguel Ojeda
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