linux-kernel - Re: [GIT PULL] Pin control fixes for v6.7

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Message-ID: <CACRpkdZRf7bNVmJCgsVD0uheD1VLkLKG13d1oS-kbT8BFyRKQw@mail.gmail.com>
Date:   Wed, 29 Nov 2023 16:08:40 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Maria Yu <quic_aiquny@...cinc.com>,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Chester Lin <clin@...e.com>
Subject: Re: [GIT PULL] Pin control fixes for v6.7

On Wed, Nov 29, 2023 at 3:56 PM Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
> On Wed, 29 Nov 2023 at 04:09, Linus Walleij <linus.walleij@...aro.org> wrote:
> >
> > The most interesting patch is the list iterator fix in the core by Maria
> > Yu, it took a while for me to realize what was going on there.
>
> That commit message still doesn't explain what the problem was.
>
> Why is p->state volatile there? It seems to be a serious locking bug
> if p->state can randomly change there, and the READ_ONCE() looks like
> a "this hides the problem" rather than an actual real fix.

Thanks for looking into it Linus, Maria can you look closer at this and
try to pinpoint exactly what happens?

Is the bug never manifesting with GCC for example?

In the meantime I'll cook a fixes branch without this one commit.

Yours,
Linus Walleij