linux-kernel - Re: [for-next PATCH v2 1/2] RDMA/rxe: Remove unnecessary mr testing

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Message-ID: <58522e46-9d45-53f3-9a19-351cc58c88e9@fujitsu.com>
Date:   Mon, 24 Oct 2022 11:26:37 +0800
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
Subject: Re: [for-next PATCH v2 1/2] RDMA/rxe: Remove unnecessary mr testing

Just noticed i didn't post [2/2] successfully, will sent it in next version.



On 21/10/2022 15:52, Li Zhijian wrote:
> Before the testing, we already passed it to rxe_mr_copy() where mr could
> be dereferenced. so this checking is not exactly correct.
>
> I tried to figure out the details how/when mr could be NULL, but failed
> at last. Add a WARN_ON(!mr) to that path to tell us more when it
> happends.
>
> Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
> ---
>   drivers/infiniband/sw/rxe/rxe_resp.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
> index ed5a09e86417..218c14fb07c6 100644
> --- a/drivers/infiniband/sw/rxe/rxe_resp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_resp.c
> @@ -778,6 +778,7 @@ static enum resp_states read_reply(struct rxe_qp *qp,
>   	if (res->state == rdatm_res_state_new) {
>   		if (!res->replay) {
>   			mr = qp->resp.mr;
> +			WARN_ON(!mr);
>   			qp->resp.mr = NULL;
>   		} else {
>   			mr = rxe_recheck_mr(qp, res->read.rkey);
> @@ -811,8 +812,7 @@ 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;