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

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Date:   Mon, 24 Oct 2022 09:10:15 -0500
From:   Bob Pearson <rpearsonhpe@...il.com>
To:     Li Zhijian <lizhijian@...itsu.com>, zyjzyj2000@...il.com,
        jgg@...pe.ca, leon@...nel.org, linux-rdma@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH for-next v3 1/2] RDMA/rxe: Remove unnecessary mr testing

On 10/23/22 22:31, Li Zhijian wrote:
> 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;

Reviewed-by: Bob Pearson <rpearsonhpe@...il.com>