linux-kernel - Re: [PATCH] iommu/vt-d: Remove unnecessary locking in intel_irq_remapping

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Message-ID: <ad57d47e-3f54-0e63-5cef-d786dab5535c@linux.intel.com>
Date:   Mon, 27 Mar 2023 21:13:10 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     Jason Gunthorpe <jgg@...dia.com>
Cc:     baolu.lu@...ux.intel.com, iommu@...ts.linux.dev,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Kevin Tian <kevin.tian@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu/vt-d: Remove unnecessary locking in
 intel_irq_remapping_alloc()

On 2023/3/27 20:18, Jason Gunthorpe wrote:
> On Tue, Mar 14, 2023 at 01:18:36PM +0800, Lu Baolu wrote:
>> The global rwsem dmar_global_lock was introduced by commit 3a5670e8ac932
>> ("iommu/vt-d: Introduce a rwsem to protect global data structures"). It
>> is used to protect DMAR related global data from DMAR hotplug operations.
>>
>> Using dmar_global_lock in intel_irq_remapping_alloc() is unnecessary as
>> the DMAR global data structures are not touched there. Remove it to avoid
>> below lockdep warning.
> 
> Tested-by: Jason Gunthorpe <jgg@...dia.com>
> 
> Solves my splat too
> 
> Let's send this to -rc please

Thank you for the testing. I will queue it for Joerg this week.

Best regards,
baolu