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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: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Jason Gunthorpe 2018-07-25 21:40:15 -06:00
parent 7452a3c745
commit 1e857e65d4
1 changed files with 26 additions and 11 deletions
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37
drivers/infiniband/core/rdma_core.c
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@ -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,