linux-kernel - Re: [PATCH v2 5/6] gpiolib: switch the line state notifier to atomic

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAMRc=Mdf8CLQDPL8RMyWPyx8362xS3jEBe4zM=JL_dzRgF5wow@mail.gmail.com>
Date: Mon, 14 Oct 2024 11:27:05 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Kent Gibson <warthog618@...il.com>
Cc: Linus Walleij <linus.walleij@...aro.org>, linux-gpio@...r.kernel.org, 
	linux-kernel@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v2 5/6] gpiolib: switch the line state notifier to atomic

On Mon, Oct 14, 2024 at 11:24 AM Kent Gibson <warthog618@...il.com> wrote:
>
> On Mon, Oct 14, 2024 at 09:48:16AM +0200, Bartosz Golaszewski wrote:
> > On Mon, Oct 14, 2024 at 4:11 AM Kent Gibson <warthog618@...il.com> wrote:
> > > >
> > > > +     /*
> > > > +      * This is called from atomic context (with a spinlock taken by the
> > > > +      * atomic notifier chain). Any sleeping calls must be done outside of
> > > > +      * this function in process context of the dedicated workqueue.
> > > > +      *
> > > > +      * Let's gather as much info as possible from the descriptor and
> > > > +      * postpone just the call to pinctrl_gpio_can_use_line() until the work
> > > > +      * is executed.
> > > > +      */
> > > > +
> > >
> > > Should be in patch 4?  You aren't otherwise changing that function here.
> > >
> >
> > Until this patch, the comment isn't really true, so I figured it makes
> > more sense here.
> >
>
> So the validity of the comment depends on how the function is being called?
> Then perhaps you should reword it as well.
>

The validity of the comment depends on the type of the notifier used.
As long as it's a blocking notifier, it's called with a mutex taken -
it's process context. When we switch to the atomic notifier, this
function is now called with a spinlock taken, so it's considered
atomic.

Bart