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

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Date:   Tue, 15 Feb 2022 08:46:05 +0100
From:   Helge Deller <deller@....de>
To:     Al Viro <viro@...iv.linux.org.uk>, Arnd Bergmann <arnd@...nel.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Christoph Hellwig <hch@....de>, linux-arch@...r.kernel.org,
        linux-mm@...ck.org, linux-api@...r.kernel.org, arnd@...db.de,
        linux-kernel@...r.kernel.org, linux@...linux.org.uk,
        will@...nel.org, guoren@...nel.org, bcain@...eaurora.org,
        geert@...ux-m68k.org, monstr@...str.eu, tsbogend@...ha.franken.de,
        nickhu@...estech.com, green.hu@...il.com, dinguyen@...nel.org,
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        mingo@...hat.com, mark.rutland@....com, hca@...ux.ibm.com,
        dalias@...c.org, davem@...emloft.net, richard@....at,
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Subject: Re: [PATCH 14/14] uaccess: drop set_fs leftovers

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?

Thanks,
Helge