From: Pedro Falcato <pfalcato@suse.de>
To: Brendan Jackman <jackmanb@google.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Vlastimil Babka <vbabka@suse.cz>, Jann Horn <jannh@google.com>,
linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org,
linux-mm@kvack.org
Subject: Re: [PATCH v2 1/4] tools/include: Implement a couple of atomic_t ops
Date: Mon, 1 Sep 2025 11:27:47 +0100 [thread overview]
Message-ID: <tnbyxwmcwia3teewhqlpdjk7igsljfqcqbze2rbalzidccfndy@e3ybvfap4pbd> (raw)
In-Reply-To: <20250828-b4-vma-no-atomic-h-v2-1-02d146a58ed2@google.com>
On Thu, Aug 28, 2025 at 12:27:58PM +0000, Brendan Jackman wrote:
> The VMA tests need an operation equivalent to
> atomic_inc_unless_negative() to implement a fake mapping_map_writable().
> Adding it will enable them to switch to the shared atomic headers and
> simplify that fake implementation.
>
> In order to add that, also add atomic_try_cmpxchg() which can be used to
> implement it. This is copied from Documentation/atomic_t.txt. Then,
> implement atomic_inc_unless_negative() itself based on the
> raw_atomic_dec_unless_positive() in
> include/linux/atomic/atomic-arch-fallback.h.
>
> There's no present need for a highly-optimised version of this (nor any
> reason to think this implementation is sub-optimal on x86) so just
> implement this with generic C, no x86-specifics.
>
> Signed-off-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
LGTM, thanks!
--
Pedro
next prev parent reply other threads:[~2025-09-01 10:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-28 12:27 [PATCH v2 0/4] tools: testing: Use existing atomic.h for vma/maple tests Brendan Jackman
2025-08-28 12:27 ` [PATCH v2 1/4] tools/include: Implement a couple of atomic_t ops Brendan Jackman
2025-09-01 10:27 ` Pedro Falcato [this message]
2025-08-28 12:27 ` [PATCH v2 2/4] tools: testing: Allow importing arch headers in shared.mk Brendan Jackman
2025-08-28 12:28 ` [PATCH v2 3/4] tools: testing: Support EXTRA_CFLAGS " Brendan Jackman
2025-08-28 12:28 ` [PATCH v2 4/4] tools: testing: Use existing atomic.h for vma/maple tests Brendan Jackman
2025-09-01 10:29 ` Pedro Falcato
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