IB/uverbs: Fix unbalanced unlock on error path for rdma_explicit_destroy

BugLink: http://bugs.launchpad.net/bugs/1786352
[ Upstream commit ec6f8401c48a86809237e86878a6fac6b281118f ]

If remove_commit fails then the lock is left locked while the uobj still
exists. Eventually the kernel will deadlock.

lockdep detects this and says:

 test/4221 is leaving the kernel with locks still held!
 1 lock held by test/4221:
  #0:  (&ucontext->cleanup_rwsem){.+.+}, at: [<000000001e5c7523>] rdma_explicit_destroy+0x37/0x120 [ib_uverbs]

Fixes: 4da70da23e9b ("IB/core: Explicitly destroy an object while keeping uobject")
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/infiniband/core/rdma_core.c b/drivers/infiniband/core/rdma_core.c
index 9cb801d1fe5432c918d1dba398b30ca58e8902f1..1984d6cee3e0c886b53939beeeb420fd817d742a 100644 (file)
--- a/drivers/infiniband/core/rdma_core.c
+++ b/drivers/infiniband/core/rdma_core.c
@@ -486,12 +486,13 @@ int rdma_explicit_destroy(struct ib_uobject *uobject)
        ret = uobject->type->type_class->remove_commit(uobject,
                                                       RDMA_REMOVE_DESTROY);
        if (ret)
-               return ret;
+               goto out;
 
        uobject->type = &null_obj_type;
 
+out:
        up_read(&ucontext->cleanup_rwsem);
-       return 0;
+       return ret;
 }
 
 static void alloc_commit_idr_uobject(struct ib_uobject *uobj)