From 1e857e65d4bb76738d3fb3b15ce9b73a0ce550f8 Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Wed, 25 Jul 2018 21:40:15 -0600 Subject: [PATCH] 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 --- drivers/infiniband/core/rdma_core.c | 37 ++++++++++++++++++++--------- 1 file changed, 26 insertions(+), 11 deletions(-) diff --git a/drivers/infiniband/core/rdma_core.c b/drivers/infiniband/core/rdma_core.c index 81d668abe18e..95a8110f186f 100644 --- a/drivers/infiniband/core/rdma_core.c +++ b/drivers/infiniband/core/rdma_core.c @@ -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,