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Commit 1e857e65 authored by Jason Gunthorpe's avatar Jason Gunthorpe
Browse files

IB/uverbs: Allow uobject allocation to work concurrently with disassociate 



After all the recent structural changes this is now straightforward, hold
the hw_destroy_rwsem across the entire uobject creation. We already take
this semaphore on the success path, so holding it a bit longer is not
going to change the performance.

After this change none of the create callbacks require the
disassociate_srcu lock to be correct.

Signed-off-by: default avatarJason Gunthorpe <jgg@mellanox.com>
parent 7452a3c7

drivers/infiniband/core/rdma_core.c

+26 −11
Original line number Diff line number Diff line
@@ -153,9 +153,8 @@ static void assert_uverbs_usecnt(struct ib_uobject *uobj, 
}



/*

 * This must be called with the hw_destroy_rwsem locked (except for

 * RDMA_REMOVE_ABORT) for read or write, also The uobject itself must be

 * locked for write.

 * This must be called with the hw_destroy_rwsem locked for read or write,

 * also the uobject itself must be locked for write.

 *

 * Upon return the HW object is guaranteed to be destroyed.

 *
@@ -177,6 +176,7 @@ static int uverbs_destroy_uobject(struct ib_uobject *uobj, 
	unsigned long flags;

	int ret;



	lockdep_assert_held(&ufile->hw_destroy_rwsem);

	assert_uverbs_usecnt(uobj, UVERBS_LOOKUP_WRITE);



	if (uobj->object) {
@@ -515,7 +515,22 @@ static struct ib_uobject *alloc_begin_fd_uobject(const struct uverbs_obj_type *t 
struct ib_uobject *rdma_alloc_begin_uobject(const struct uverbs_obj_type *type,

					    struct ib_uverbs_file *ufile)

{

	return type->type_class->alloc_begin(type, ufile);

	struct ib_uobject *ret;



	/*

	 * The hw_destroy_rwsem is held across the entire object creation and

	 * released during rdma_alloc_commit_uobject or

	 * rdma_alloc_abort_uobject

	 */

	if (!down_read_trylock(&ufile->hw_destroy_rwsem))

		return ERR_PTR(-EIO);



	ret = type->type_class->alloc_begin(type, ufile);

	if (IS_ERR(ret)) {

		up_read(&ufile->hw_destroy_rwsem);

		return ret;

	}

	return ret;

}



static void alloc_abort_idr_uobject(struct ib_uobject *uobj)
@@ -637,17 +652,11 @@ int __must_check rdma_alloc_commit_uobject(struct ib_uobject *uobj) 
	struct ib_uverbs_file *ufile = uobj->ufile;

	int ret;



	/* Cleanup is running. Calling this should have been impossible */

	if (!down_read_trylock(&ufile->hw_destroy_rwsem)) {

		WARN(true, "ib_uverbs: Cleanup is running while allocating an uobject\n");

		uverbs_destroy_uobject(uobj, RDMA_REMOVE_ABORT);

		return -EINVAL;

	}



	/* alloc_commit consumes the uobj kref */

	ret = uobj->type->type_class->alloc_commit(uobj);

	if (ret) {

		uverbs_destroy_uobject(uobj, RDMA_REMOVE_ABORT);

		up_read(&ufile->hw_destroy_rwsem);

		return ret;

	}
@@ -660,6 +669,7 @@ int __must_check rdma_alloc_commit_uobject(struct ib_uobject *uobj) 
	/* matches atomic_set(-1) in alloc_uobj */

	atomic_set(&uobj->usecnt, 0);



	/* Matches the down_read in rdma_alloc_begin_uobject */

	up_read(&ufile->hw_destroy_rwsem);



	return 0;
@@ -671,8 +681,13 @@ int __must_check rdma_alloc_commit_uobject(struct ib_uobject *uobj) 
 */

void rdma_alloc_abort_uobject(struct ib_uobject *uobj)

{

	struct ib_uverbs_file *ufile = uobj->ufile;



	uobj->object = NULL;

	uverbs_destroy_uobject(uobj, RDMA_REMOVE_ABORT);



	/* Matches the down_read in rdma_alloc_begin_uobject */

	up_read(&ufile->hw_destroy_rwsem);

}



static void lookup_put_idr_uobject(struct ib_uobject *uobj,