linux-kernel - Re: [PATCH] spin_lock_irqsave() in autofs

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Message-ID: <CAHk-=wj-NB_5KTCj7yhBsF145oLDuxQPt4J87tXsd6j+p3vzDw@mail.gmail.com>
Date: Sun, 17 Aug 2025 09:50:25 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Al Viro <viro@...iv.linux.org.uk>
Cc: Ian Kent <raven@...maw.net>, autofs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] spin_lock_irqsave() in autofs_write() is bogus

On Sun, 17 Aug 2025 at 09:36, Al Viro <viro@...iv.linux.org.uk> wrote:
>
>         That function should never be (and never is) called with irqs
> disabled - we have an explicit mutex_lock() in there, if nothing else.
> Which makes spin_lock_irqsave() use in there pointless - we do need to
> disable irqs for ->siglock, but that should be spin_lock_irq().

I think we basically did the irqsave/restore version as the default
when not wanting to think about the context.

Your patch looks fine, but I doubt it's measurable outside of "it
makes the code a few bytes smaller".

So ACK on it, but I'm not convinced it's worth spending time actively
_looking_ for these kinds of things.

            Linus