diff options
| author | Jason Gunthorpe <jgg@nvidia.com> | 2023-07-17 21:12:11 +0300 |
|---|---|---|
| committer | Jason Gunthorpe <jgg@nvidia.com> | 2023-07-26 16:20:21 +0300 |
| commit | 83f7bc6fdfd2fca11f35c061194d60f88acb3086 (patch) | |
| tree | f755bb24f7583042167de06ab6074708a032a1c1 | |
| parent | e88d4ec154a87884086d3e38f2dfc66aec11bf8c (diff) | |
| download | linux-83f7bc6fdfd2fca11f35c061194d60f88acb3086.tar.xz | |
iommufd: Make destroy_rwsem use a lock class per object type
The selftest invokes things like replace under the object lock of its
idev which protects the idev in a similar way to a real user.
Unfortunately this triggers lockdep. A lock class per type will solve the
problem.
Link: https://lore.kernel.org/r/15-v8-6659224517ea+532-iommufd_alloc_jgg@nvidia.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
| -rw-r--r-- | drivers/iommu/iommufd/iommufd_private.h | 1 | ||||
| -rw-r--r-- | drivers/iommu/iommufd/main.c | 11 |
2 files changed, 11 insertions, 1 deletions
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index 47fed9feefd0..9394f0e6692a 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -119,6 +119,7 @@ enum iommufd_object_type { #ifdef CONFIG_IOMMUFD_TEST IOMMUFD_OBJ_SELFTEST, #endif + IOMMUFD_OBJ_MAX, }; /* Base struct for all objects with a userspace ID handle. */ diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c index 521225c6a071..56cdf3c796a7 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -33,6 +33,7 @@ struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx, size_t size, enum iommufd_object_type type) { + static struct lock_class_key obj_keys[IOMMUFD_OBJ_MAX]; struct iommufd_object *obj; int rc; @@ -40,7 +41,15 @@ struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx, if (!obj) return ERR_PTR(-ENOMEM); obj->type = type; - init_rwsem(&obj->destroy_rwsem); + /* + * In most cases the destroy_rwsem is obtained with try so it doesn't + * interact with lockdep, however on destroy we have to sleep. This + * means if we have to destroy an object while holding a get on another + * object it triggers lockdep. Using one locking class per object type + * is a simple and reasonable way to avoid this. + */ + __init_rwsem(&obj->destroy_rwsem, "iommufd_object::destroy_rwsem", + &obj_keys[type]); refcount_set(&obj->users, 1); /* |