linux-kernel - Re: [cpuops cmpxchg double V1 1/4] Generic support for this_cpu_cmpxchg

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4D0CC982.3030905@kernel.org>
Date:	Sat, 18 Dec 2010 15:47:30 +0100
From:	Tejun Heo <tj@...nel.org>
To:	Christoph Lameter <cl@...ux.com>
CC:	akpm@...ux-foundation.org, Pekka Enberg <penberg@...helsinki.fi>,
	linux-kernel@...r.kernel.org,
	Eric Dumazet <eric.dumazet@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: [cpuops cmpxchg double V1 1/4] Generic support for this_cpu_cmpxchg_double

Hello, Christoph.

On 12/14/2010 06:48 PM, Christoph Lameter wrote:
> +/*
> + * cmpxchg_double replaces two adjacent scalars at once. The first parameter
> + * passed is a percpu pointer, not a scalar like the other this_cpu
> + * operations. This is so because the function operates on two scalars
> + * (must be of same size). A truth value is returned to indicate success or
> + * failure (since a double register result is difficult to handle).
> + * There is very limited hardware support for these operations. So only certain
> + * sizes may work.
> + */
> +#define __this_cpu_generic_cmpxchg_double(pcp, oval1, oval2, nval1, nval2)	

This is ugly. :-( I think we should have made this_cpu_*() ops take
pointers from the beginning.  Anyways, that's too late, so is it
completely impossible to make cmpxchg_double's take a scalar value?
It can take the pointer all the same, no?

Thanks.

-- 
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/