From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leon Romanovsky Subject: [PATCH rdma-rc 10/15] IB/uverbs: Hold the uobj write lock after allocate Date: Tue, 13 Feb 2018 12:18:36 +0200 Message-ID: <20180213101841.20101-11-leon@kernel.org> References: <20180213101841.20101-1-leon@kernel.org> Return-path: In-Reply-To: <20180213101841.20101-1-leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Doug Ledford , Jason Gunthorpe Cc: Leon Romanovsky , RDMA mailing list , Alaa Hleihel , Matan Barak , Noa Osherovich List-Id: linux-rdma@vger.kernel.org From: Jason Gunthorpe This clarifies the design intention that time between allocate and commit has the uobj exclusive to the caller. We already guarantee this by delaying publishing the uobj pointer via idr_insert, fd_install, list_add, etc. Additionally holding the usecnt lock during this period provides extra clarity and more protection against future mistakes. Fixes: 3832125624b7 ("IB/core: Add support for idr types") Signed-off-by: Jason Gunthorpe Signed-off-by: Leon Romanovsky --- drivers/infiniband/core/rdma_core.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/core/rdma_core.c b/drivers/infiniband/core/rdma_core.c index 85b5ee4defa4..82afb0cdcca3 100644 --- a/drivers/infiniband/core/rdma_core.c +++ b/drivers/infiniband/core/rdma_core.c @@ -141,7 +141,12 @@ static struct ib_uobject *alloc_uobj(struct ib_ucontext *context, */ uobj->context = context; uobj->type = type; - atomic_set(&uobj->usecnt, 0); + /* + * Allocated objects start out as write locked to deny any other + * syscalls from accessing them until they are commited. See + * rdma_alloc_commit_uobject + */ + atomic_set(&uobj->usecnt, -1); kref_init(&uobj->ref); return uobj; @@ -527,6 +532,10 @@ int rdma_alloc_commit_uobject(struct ib_uobject *uobj) return ret; } + /* matches atomic_set(-1) in alloc_uobj */ + lockdep_check(uobj, true); + atomic_set(&uobj->usecnt, 0); + uobj->type->type_class->alloc_commit(uobj); up_read(&uobj->context->cleanup_rwsem); -- 2.16.1 -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html