From: Baolu Lu <baolu.lu@linux.intel.com>
To: Uros Bizjak <ubizjak@gmail.com>,
iommu@lists.linux.dev, linux-kernel@vger.kernel.org
Cc: baolu.lu@linux.intel.com, David Woodhouse <dwmw2@infradead.org>,
Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH] iommu/intel: Use try_cmpxchg64{,_local}() in iommu.c
Date: Wed, 24 Apr 2024 11:44:55 +0800 [thread overview]
Message-ID: <4b3f6af7-d40e-4910-8e6d-449c59ab0dd2@linux.intel.com> (raw)
In-Reply-To: <20240414162454.49584-1-ubizjak@gmail.com>
On 4/15/24 12:23 AM, Uros Bizjak wrote:
> Replace this pattern in iommu.c:
>
> cmpxchg64{,_local}(*ptr, 0, new) != 0
>
> .. with the simpler and faster:
>
> !try_cmpxchg64{,_local}(*ptr, &tmp, new)
>
> The x86 CMPXCHG instruction returns success in the ZF flag, so this change
> saves a compare after the CMPXCHG.
>
> No functional change intended.
>
> Signed-off-by: Uros Bizjak<ubizjak@gmail.com>
> Cc: David Woodhouse<dwmw2@infradead.org>
> Cc: Lu Baolu<baolu.lu@linux.intel.com>
> Cc: Joerg Roedel<joro@8bytes.org>
> Cc: Will Deacon<will@kernel.org>
> Cc: Robin Murphy<robin.murphy@arm.com>
> ---
> drivers/iommu/intel/iommu.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
Patch has been queued for iommu/vt-d.
Best regards,
baolu
prev parent reply other threads:[~2024-04-24 3:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-14 16:23 [PATCH] iommu/intel: Use try_cmpxchg64{,_local}() in iommu.c Uros Bizjak
2024-04-15 16:31 ` Jason Gunthorpe
2024-04-24 3:44 ` Baolu Lu [this message]
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