smb: server: make use of rdma_destroy_qp()

The qp is created by rdma_create_qp() as t->cm_id->qp
and t->qp is just a shortcut.

rdma_destroy_qp() also calls ib_destroy_qp(cm_id->qp) internally,
but it is protected by a mutex, clears the cm_id and also calls
trace_cm_qp_destroy().

This should make the tracing more useful as both
rdma_create_qp() and rdma_destroy_qp() are traces and it makes
the code look more sane as functions from the same layer are used
for the specific qp object.

trace-cmd stream -e rdma_cma:cm_qp_create -e rdma_cma:cm_qp_destroy
shows this now while doing a mount and unmount from a client:

  <...>-80   [002] 378.514182: cm_qp_create:  cm.id=1 src=172.31.9.167:5445 dst=172.31.9.166:37113 tos=0 pd.id=0 qp_type=RC send_wr=867 recv_wr=255 qp_num=1 rc=0
  <...>-6283 [001] 381.686172: cm_qp_destroy: cm.id=1 src=172.31.9.167:5445 dst=172.31.9.166:37113 tos=0 qp_num=1

Before we only saw the first line.

Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Steve French <stfrench@microsoft.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Hyunchul Lee <hyc.lee@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: linux-cifs@vger.kernel.org
Fixes: 0626e66 ("cifsd: add server handler for central processing and tranport layers")
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Tom Talpey <tom@talpey.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: metze-samba

fs/smb/server/transport_rdma.c

@@ -433,7 +433,8 @@ static void free_transport(struct smb_direct_transport *t)
 	if (t->qp) {
 		ib_drain_qp(t->qp);
 		ib_mr_pool_destroy(t->qp, &t->qp->rdma_mrs);
-		ib_destroy_qp(t->qp);
+		t->qp = NULL;
+		rdma_destroy_qp(t->cm_id);
 	}
 
 	ksmbd_debug(RDMA, "drain the reassembly queue\n");
@@ -1940,8 +1941,8 @@ static int smb_direct_create_qpair(struct smb_direct_transport *t,
 	return 0;
 err:
 	if (t->qp) {
-		ib_destroy_qp(t->qp);
 		t->qp = NULL;
+		rdma_destroy_qp(t->cm_id);
 	}
 	if (t->recv_cq) {
 		ib_destroy_cq(t->recv_cq);