linux-kernel - Re: [PATCH 14/14] uaccess: drop set

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Date:   Tue, 15 Feb 2022 09:10:05 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Helge Deller <deller@....de>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Christoph Hellwig <hch@....de>,
        linux-arch <linux-arch@...r.kernel.org>,
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Subject: Re: [PATCH 14/14] uaccess: drop set_fs leftovers

On Tue, Feb 15, 2022 at 8:46 AM Helge Deller <deller@....de> wrote:
>
> On 2/15/22 04:03, Al Viro wrote:
> > On Mon, Feb 14, 2022 at 05:34:52PM +0100, Arnd Bergmann wrote:
> >> diff --git a/arch/parisc/include/asm/futex.h b/arch/parisc/include/asm/futex.h
> >> index b5835325d44b..2f4a1b1ef387 100644
> >> --- a/arch/parisc/include/asm/futex.h
> >> +++ b/arch/parisc/include/asm/futex.h
> >> @@ -99,7 +99,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
> >>      /* futex.c wants to do a cmpxchg_inatomic on kernel NULL, which is
> >>       * our gateway page, and causes no end of trouble...
> >>       */
> >> -    if (uaccess_kernel() && !uaddr)
> >> +    if (!uaddr)
> >>              return -EFAULT;
> >
> >       Huh?  uaccess_kernel() is removed since it becomes always false now,
> > so this looks odd.
> >
> >       AFAICS, the comment above that check refers to futex_detect_cmpxchg()
> > -> cmpxchg_futex_value_locked() -> futex_atomic_cmpxchg_inatomic() call chain.
> > Which had been gone since commit 3297481d688a (futex: Remove futex_cmpxchg
> > detection).  The comment *and* the check should've been killed off back
> > then.
> >       Let's make sure to get both now...
>
> Right. Arnd, can you drop this if() and the comment above it?

Done.

       Arnd