linux-kernel - [PATCH for-next v3 1/2] RDMA/rxe: Remove unnecessary mr testing

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Date:   Mon, 24 Oct 2022 03:31:54 +0000
From:   Li Zhijian <lizhijian@...itsu.com>
To:     <zyjzyj2000@...il.com>, <jgg@...pe.ca>, <leon@...nel.org>,
        <linux-rdma@...r.kernel.org>
CC:     <linux-kernel@...r.kernel.org>, Li Zhijian <lizhijian@...itsu.com>,
        "Bob Pearson" <rpearsonhpe@...il.com>
Subject: [PATCH for-next v3 1/2] RDMA/rxe: Remove unnecessary mr testing

Before the testing, we already passed it to rxe_mr_copy() where mr could
be dereferenced. so this checking is not needed.

The only way that mr is NULL is when it reaches below line 780 with
 'qp->resp.mr = NULL', which is not possible in Bob's explanation[1].

 778         if (res->state == rdatm_res_state_new) {
 779                 if (!res->replay) {
 780                         mr = qp->resp.mr;
 781                         qp->resp.mr = NULL;
 782                 } else {

[1] https://lore.kernel.org/lkml/30ff25c4-ce66-eac4-eaa2-64c0db203a19@gmail.com/

CC: Bob Pearson <rpearsonhpe@...il.com>
Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
---
V3: remove WARN_ON # Yanjun and Bob
---
 drivers/infiniband/sw/rxe/rxe_resp.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
index ed5a09e86417..b02639cf8cba 100644
--- a/drivers/infiniband/sw/rxe/rxe_resp.c
+++ b/drivers/infiniband/sw/rxe/rxe_resp.c
@@ -811,8 +811,7 @@ static enum resp_states read_reply(struct rxe_qp *qp,
 
 	rxe_mr_copy(mr, res->read.va, payload_addr(&ack_pkt),
 		    payload, RXE_FROM_MR_OBJ);
-	if (mr)
-		rxe_put(mr);
+	rxe_put(mr);
 
 	if (bth_pad(&ack_pkt)) {
 		u8 *pad = payload_addr(&ack_pkt) + payload;
-- 
1.8.3.1