From: Jason Gunthorpe <jgg@nvidia.com>
To: Nicolin Chen <nicolinc@nvidia.com>
Cc: will@kernel.org, robin.murphy@arm.com, joro@8bytes.org,
jpb@kernel.org, praan@google.com, miko.lenczewski@arm.com,
linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev,
linux-kernel@vger.kernel.org, patches@lists.linux.dev
Subject: Re: [PATCH v2 04/10] iommu/arm-smmu-v3: Allocate IOTLB cache tag if no id to reuse
Date: Tue, 27 Jan 2026 12:29:08 -0400 [thread overview]
Message-ID: <20260127162908.GL1134360@nvidia.com> (raw)
In-Reply-To: <aXfpaN4UCYcY9W8T@Asurada-Nvidia>
On Mon, Jan 26, 2026 at 02:23:36PM -0800, Nicolin Chen wrote:
> On Mon, Jan 26, 2026 at 05:06:40PM -0400, Jason Gunthorpe wrote:
> > On Wed, Jan 21, 2026 at 05:24:22PM -0800, Nicolin Chen wrote:
> > > @@ -3220,6 +3241,9 @@ arm_smmu_master_build_inv(struct arm_smmu_master *master,
> > > break;
> > > }
> > >
> > > + /* Set a default users counter */
> > > + refcount_set(&cur->users, 1);
> >
> > I think abusing users here is a little too hard to read..
> >
> > Can we just keep track in the state somehow with a flag?
> >
> > Or maybe union in a "bool needs_free" that is for the on-stack version
> > of this structure?
>
> This doesn't only apply to the case when a tag is newly allocated
> during the attach, but it can be used when an old tag has users=0
> during a detach, right?
Oh, IDK, I didn't look so closely..
I though this was just about cleaning up the tag during attach, the
detach flow worked differently and did use users = 0?
Jason
next prev parent reply other threads:[~2026-01-27 16:29 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-22 1:24 [PATCH v2 00/10] iommu/arm-smmu-v3: Share domain across SMMU/vSMMU instances Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 01/10] iommu/arm-smmu-v3: Store IOTLB cache tags in struct arm_smmu_attach_state Nicolin Chen
2026-01-26 20:44 ` Jason Gunthorpe
2026-01-27 3:23 ` Nicolin Chen
2026-01-27 15:08 ` Jason Gunthorpe
2026-01-27 16:58 ` Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 02/10] iommu/arm-smmu-v3: Pass in IOTLB cache tag to CD and STE Nicolin Chen
2026-01-26 20:53 ` Jason Gunthorpe
2026-01-27 3:28 ` Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 03/10] iommu/arm-smmu-v3: Look for existing iotlb tag in smmu_domain->invs Nicolin Chen
2026-01-26 21:03 ` Jason Gunthorpe
2026-01-27 2:50 ` Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 04/10] iommu/arm-smmu-v3: Allocate IOTLB cache tag if no id to reuse Nicolin Chen
2026-01-26 21:06 ` Jason Gunthorpe
2026-01-26 22:23 ` Nicolin Chen
2026-01-27 16:29 ` Jason Gunthorpe [this message]
2026-01-27 16:52 ` Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 05/10] iommu/arm-smmu-v3: Flush iotlb in arm_smmu_iotlb_tag_free() Nicolin Chen
2026-01-26 21:08 ` Jason Gunthorpe
2026-01-27 2:56 ` Nicolin Chen
2026-01-27 15:09 ` Jason Gunthorpe
2026-01-22 1:24 ` [PATCH v2 06/10] iommu/arm-smmu-v3: Allocate vmid in arm_vsmmu_init Nicolin Chen
2026-01-26 21:16 ` Jason Gunthorpe
2026-01-27 3:06 ` Nicolin Chen
2026-01-27 15:11 ` Jason Gunthorpe
2026-01-27 17:11 ` Nicolin Chen
2026-01-27 17:58 ` Jason Gunthorpe
2026-01-22 1:24 ` [PATCH v2 07/10] iommu/arm-smmu-v3: Pass in vsmmu to arm_smmu_domain_get_iotlb_tag() Nicolin Chen
2026-01-26 21:20 ` Jason Gunthorpe
2026-01-27 3:34 ` Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 08/10] iommu/arm-smmu-v3: Introduce INV_TYPE_S2_VMID_VSMMU Nicolin Chen
2026-01-27 15:13 ` Jason Gunthorpe
2026-01-22 1:24 ` [PATCH v2 09/10] iommu/arm-smmu-v3: Remove ASID/VMID from arm_smmu_domain Nicolin Chen
2026-01-22 1:24 ` [PATCH v2 10/10] iommu/arm-smmu-v3: Allow sharing domain across SMMUs Nicolin Chen
2026-01-27 15:41 ` Jason Gunthorpe
2026-01-27 17:50 ` Nicolin Chen
2026-01-27 17:59 ` Jason Gunthorpe
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