From: Jason Gunthorpe <jgg@nvidia.com>
To: Nicolin Chen <nicolinc@nvidia.com>
Cc: kevin.tian@intel.com, corbet@lwn.net, joro@8bytes.org,
suravee.suthikulpanit@amd.com, will@kernel.org,
robin.murphy@arm.com, dwmw2@infradead.org, shuah@kernel.org,
iommu@lists.linux.dev, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
baolu.lu@linux.intel.com, eric.auger@redhat.com,
jean-philippe@linaro.org, mdf@kernel.org, mshavit@google.com,
shameerali.kolothum.thodi@huawei.com, smostafa@google.com,
yi.l.liu@intel.com, aik@amd.com, zhangfei.gao@linaro.org,
patches@lists.linux.dev
Subject: Re: [PATCH v6 01/10] iommufd/viommu: Add IOMMUFD_OBJ_VDEVICE and IOMMU_VDEVICE_ALLOC ioctl
Date: Thu, 31 Oct 2024 10:29:41 -0300 [thread overview]
Message-ID: <20241031132941.GL10193@nvidia.com> (raw)
In-Reply-To: <19e20e54d41a0c1ab7403264e1016c4b19293135.1730313494.git.nicolinc@nvidia.com>
On Wed, Oct 30, 2024 at 02:35:27PM -0700, Nicolin Chen wrote:
> +void iommufd_vdevice_destroy(struct iommufd_object *obj)
> +{
> + struct iommufd_vdevice *vdev =
> + container_of(obj, struct iommufd_vdevice, obj);
> + struct iommufd_viommu *viommu = vdev->viommu;
> +
> + /* xa_cmpxchg is okay to fail if alloc returned -EEXIST previously */
> + xa_cmpxchg(&viommu->vdevs, vdev->id, vdev, NULL, GFP_KERNEL);
There are crazy races that would cause this not to work. Another
thread could have successfully destroyed whatever caused EEXIST and
the successfully registered this same vdev to the same id. Then this
will wrongly erase the other threads entry.
It would be better to skip the erase directly if the EEXIST unwind is
being taken.
Jason
next prev parent reply other threads:[~2024-10-31 13:29 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-30 21:35 [PATCH v6 00/10] iommufd: Add vIOMMU infrastructure (Part-2: vDEVICE) Nicolin Chen
2024-10-30 21:35 ` [PATCH v6 01/10] iommufd/viommu: Add IOMMUFD_OBJ_VDEVICE and IOMMU_VDEVICE_ALLOC ioctl Nicolin Chen
2024-10-31 13:29 ` Jason Gunthorpe [this message]
2024-10-31 16:56 ` Nicolin Chen
2024-10-31 17:04 ` Jason Gunthorpe
2024-10-31 18:46 ` Nicolin Chen
2024-11-07 10:11 ` Alexey Kardashevskiy
2024-11-07 16:31 ` Nicolin Chen
2024-11-07 18:50 ` Jason Gunthorpe
2024-10-30 21:35 ` [PATCH v6 02/10] iommufd/selftest: Add IOMMU_VDEVICE_ALLOC test coverage Nicolin Chen
2024-10-30 21:35 ` [PATCH v6 03/10] iommu/viommu: Add cache_invalidate to iommufd_viommu_ops Nicolin Chen
2024-10-30 21:35 ` [PATCH v6 04/10] iommufd: Allow hwpt_id to carry viommu_id for IOMMU_HWPT_INVALIDATE Nicolin Chen
2024-10-30 21:35 ` [PATCH v6 05/10] iommu: Add iommu_copy_struct_from_full_user_array helper Nicolin Chen
2024-10-31 15:33 ` Jason Gunthorpe
2024-10-30 21:35 ` [PATCH v6 06/10] iommufd/viommu: Add iommufd_viommu_find_dev helper Nicolin Chen
2024-10-31 13:30 ` Jason Gunthorpe
2024-10-30 21:35 ` [PATCH v6 07/10] iommufd/selftest: Add mock_viommu_cache_invalidate Nicolin Chen
2024-10-30 21:35 ` [PATCH v6 08/10] iommufd/selftest: Add IOMMU_TEST_OP_DEV_CHECK_CACHE test command Nicolin Chen
2024-10-31 15:34 ` Jason Gunthorpe
2024-10-30 21:35 ` [PATCH v6 09/10] iommufd/selftest: Add vIOMMU coverage for IOMMU_HWPT_INVALIDATE ioctl Nicolin Chen
2024-10-31 15:36 ` Jason Gunthorpe
2024-10-30 21:35 ` [PATCH v6 10/10] Documentation: userspace-api: iommufd: Update vDEVICE Nicolin Chen
2024-10-31 6:28 ` [PATCH v6 00/10] iommufd: Add vIOMMU infrastructure (Part-2: vDEVICE) Zhangfei Gao
2024-10-31 11:59 ` Jason Gunthorpe
2024-10-31 16:43 ` Nicolin Chen
2024-10-31 16:41 ` Nicolin Chen
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