linux-kernel - Re: [patch V5 12/12] select: Convert to scoped user access

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Message-ID: <db0e0201-0bb5-4096-ad87-f2cd109d07dc@csgroup.eu>
Date: Tue, 4 Nov 2025 07:32:02 +0100
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Thomas Gleixner <tglx@...utronix.de>, LKML <linux-kernel@...r.kernel.org>
Cc: Alexander Viro <viro@...iv.linux.org.uk>,
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
 linux-fsdevel@...r.kernel.org, kernel test robot <lkp@...el.com>,
 Russell King <linux@...linux.org.uk>, linux-arm-kernel@...ts.infradead.org,
 Linus Torvalds <torvalds@...ux-foundation.org>, x86@...nel.org,
 Madhavan Srinivasan <maddy@...ux.ibm.com>,
 Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
 linuxppc-dev@...ts.ozlabs.org, Paul Walmsley <pjw@...nel.org>,
 Palmer Dabbelt <palmer@...belt.com>, linux-riscv@...ts.infradead.org,
 Heiko Carstens <hca@...ux.ibm.com>,
 Christian Borntraeger <borntraeger@...ux.ibm.com>,
 Sven Schnelle <svens@...ux.ibm.com>, linux-s390@...r.kernel.org,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Cooper <andrew.cooper3@...rix.com>,
 David Laight <david.laight.linux@...il.com>,
 Julia Lawall <Julia.Lawall@...ia.fr>, Nicolas Palix <nicolas.palix@...g.fr>,
 Peter Zijlstra <peterz@...radead.org>, Darren Hart <dvhart@...radead.org>,
 Davidlohr Bueso <dave@...olabs.net>, André Almeida
 <andrealmeid@...lia.com>
Subject: Re: [patch V5 12/12] select: Convert to scoped user access



Le 27/10/2025 à 09:44, Thomas Gleixner a écrit :
> From: Thomas Gleixner <tglx@...utronix.de>
> 
> Replace the open coded implementation with the scoped user access guard.
> 
> No functional change intended.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: Alexander Viro <viro@...iv.linux.org.uk>
> Cc: Christian Brauner <brauner@...nel.org>
> Cc: Jan Kara <jack@...e.cz>
> Cc: linux-fsdevel@...r.kernel.org

Reviewed-by: Christophe Leroy <christophe.leroy@...roup.eu>

> ---
> V4: Use read guard - Peterz
>      Rename once more
> V3: Adopt to scope changes
> ---
>   fs/select.c |   12 ++++--------
>   1 file changed, 4 insertions(+), 8 deletions(-)
> ---
> --- a/fs/select.c
> +++ b/fs/select.c
> @@ -776,17 +776,13 @@ static inline int get_sigset_argpack(str
>   {
>   	// the path is hot enough for overhead of copy_from_user() to matter
>   	if (from) {
> -		if (can_do_masked_user_access())
> -			from = masked_user_access_begin(from);
> -		else if (!user_read_access_begin(from, sizeof(*from)))
> -			return -EFAULT;
> -		unsafe_get_user(to->p, &from->p, Efault);
> -		unsafe_get_user(to->size, &from->size, Efault);
> -		user_read_access_end();
> +		scoped_user_read_access(from, Efault) {
> +			unsafe_get_user(to->p, &from->p, Efault);
> +			unsafe_get_user(to->size, &from->size, Efault);
> +		}
>   	}
>   	return 0;
>   Efault:
> -	user_read_access_end();
>   	return -EFAULT;
>   }
>   
>