Re: [PATCH 1/2] x86/memsharing: use an atomic add instead of a cmpxchg loop

From: Jan Beulich <jbeulich@suse.com>
To: Roger Pau Monne <roger.pau@citrix.com>
Cc: Tamas K Lengyel <tamas@tklengyel.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	George Dunlap <george.dunlap@citrix.com>, Wei Liu <wl@xen.org>,
	xen-devel@lists.xenproject.org
Subject: Re: [PATCH 1/2] x86/memsharing: use an atomic add instead of a cmpxchg loop
Date: Thu, 29 Feb 2024 08:37:53 +0100	[thread overview]
Message-ID: <19c837ce-534c-4b76-b8fd-f5baa9f328bd@suse.com> (raw)
In-Reply-To: <20240222090530.62530-2-roger.pau@citrix.com>

On 22.02.2024 10:05, Roger Pau Monne wrote:
> The usage of a cmpxchg loop in get_next_handle() is unnecessary, as the same
> can be achieved with an atomic increment, which is both simpler to read, and
> avoid any need for a loop.
> 
> The cmpxchg usage is likely a remnant of 32bit support, which didn't have an
> instruction to do an atomic 64bit add, and instead a cmpxchg had to be used.
> 
> Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Signed-of-by: Roger Pau Monné <roger.pau@citrix.com>

Hmm, same typo again, so my commit script again got the author wrong.
I'm sorry again. I would consider adding an explicit confirmation step
when there's no (well-formed) S-o-b, but I use this script elsewhere
as well, and in e.g. binutils and gcc S-o-b are pretty uncommon. (And
to avoid the question: I'm specifically avoiding From: itself in the
common case, as for you and other people with non-ASCII characters in
their names those typically don't properly show up there.)

Jan