IB/mthca: Add missed mthca_unmap_user_db() for mthca_create_srq()

commit 117942c upstream.

Fix a user triggerable leak on the system call failure path.

Cc: stable@vger.kernel.org
Fixes: ec34a92 ("[PATCH] IB/mthca: Add SRQ implementation")
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://patch.msgid.link/2-v1-83e918d69e73+a9-rdma_udata_rc_jgg@nvidia.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: jgunthorpe

drivers/infiniband/hw/mthca/mthca_provider.c

@@ -428,6 +428,8 @@ static int mthca_create_srq(struct ib_srq *ibsrq,
 
 	if (context && ib_copy_to_udata(udata, &srq->srqn, sizeof(__u32))) {
 		mthca_free_srq(to_mdev(ibsrq->device), srq);
+		mthca_unmap_user_db(to_mdev(ibsrq->device), &context->uar,
+				    context->db_tab, ucmd.db_index);
 		return -EFAULT;
 	}
 
@@ -436,6 +438,7 @@ static int mthca_create_srq(struct ib_srq *ibsrq,
 
 static int mthca_destroy_srq(struct ib_srq *srq, struct ib_udata *udata)
 {
+	mthca_free_srq(to_mdev(srq->device), to_msrq(srq));
 	if (udata) {
 		struct mthca_ucontext *context =
 			rdma_udata_to_drv_context(
@@ -446,8 +449,6 @@ static int mthca_destroy_srq(struct ib_srq *srq, struct ib_udata *udata)
 		mthca_unmap_user_db(to_mdev(srq->device), &context->uar,
 				    context->db_tab, to_msrq(srq)->db_index);
 	}
-
-	mthca_free_srq(to_mdev(srq->device), to_msrq(srq));
 	return 0;
 }