Re: [PATCH 4/4] RDMA/bnxt_re: synchronize the qp-handle table array

[Zhu Yanjun <yanjun.zhu@linux.dev>]

在 2024/9/12 2:29, Selvin Xavier 写道:
> There is a race between the CREQ tasklet and destroy
> qp when accessing the qp-handle table. There is
> a chance of reading a valid qp-handle in the
> CREQ tasklet handler while the QP is already moving
> ahead with the destruction.
> 
> Fixing this race by implementing a table-lock to
> synchronize the access.
> 
> Fixes: f218d67ef004 ("RDMA/bnxt_re: Allow posting when QPs are in error")
> Fixes: 84cf229f4001 ("RDMA/bnxt_re: Fix the qp table indexing")
> Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
> Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
> ---
>   drivers/infiniband/hw/bnxt_re/qplib_fp.c   |  5 +++++
>   drivers/infiniband/hw/bnxt_re/qplib_rcfw.c | 12 ++++++++----
>   drivers/infiniband/hw/bnxt_re/qplib_rcfw.h |  2 ++
>   3 files changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/infiniband/hw/bnxt_re/qplib_fp.c b/drivers/infiniband/hw/bnxt_re/qplib_fp.c
> index 42e98e5..5d36216 100644
> --- a/drivers/infiniband/hw/bnxt_re/qplib_fp.c
> +++ b/drivers/infiniband/hw/bnxt_re/qplib_fp.c
> @@ -1524,12 +1524,15 @@ int bnxt_qplib_destroy_qp(struct bnxt_qplib_res *res,
>   	struct creq_destroy_qp_resp resp = {};
>   	struct bnxt_qplib_cmdqmsg msg = {};
>   	struct cmdq_destroy_qp req = {};
> +	unsigned long flags;
>   	u32 tbl_indx;
>   	int rc;
>   
> +	spin_lock_irqsave(&rcfw->tbl_lock, flags);

Because the race occurs between tasklets, spin_lock_bh is enough to this?

Zhu Yanjun

>   	tbl_indx = map_qp_id_to_tbl_indx(qp->id, rcfw);
>   	rcfw->qp_tbl[tbl_indx].qp_id = BNXT_QPLIB_QP_ID_INVALID;
>   	rcfw->qp_tbl[tbl_indx].qp_handle = NULL;
> +	spin_unlock_irqrestore(&rcfw->tbl_lock, flags);
>   
>   	bnxt_qplib_rcfw_cmd_prep((struct cmdq_base *)&req,
>   				 CMDQ_BASE_OPCODE_DESTROY_QP,
> @@ -1540,8 +1543,10 @@ int bnxt_qplib_destroy_qp(struct bnxt_qplib_res *res,
>   				sizeof(resp), 0);
>   	rc = bnxt_qplib_rcfw_send_message(rcfw, &msg);
>   	if (rc) {
> +		spin_lock_irqsave(&rcfw->tbl_lock, flags);
>   		rcfw->qp_tbl[tbl_indx].qp_id = qp->id;
>   		rcfw->qp_tbl[tbl_indx].qp_handle = qp;
> +		spin_unlock_irqrestore(&rcfw->tbl_lock, flags);
>   		return rc;
>   	}
>   
> diff --git a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c
> index 3ffaef0c..993c356 100644
> --- a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c
> +++ b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c
> @@ -637,17 +637,21 @@ static int bnxt_qplib_process_qp_event(struct bnxt_qplib_rcfw *rcfw,
>   	case CREQ_QP_EVENT_EVENT_QP_ERROR_NOTIFICATION:
>   		err_event = (struct creq_qp_error_notification *)qp_event;
>   		qp_id = le32_to_cpu(err_event->xid);
> +		spin_lock(&rcfw->tbl_lock);
>   		tbl_indx = map_qp_id_to_tbl_indx(qp_id, rcfw);
>   		qp = rcfw->qp_tbl[tbl_indx].qp_handle;
> +		if (!qp) {
> +			spin_unlock(&rcfw->tbl_lock);
> +			break;
> +		}
> +		bnxt_qplib_mark_qp_error(qp);
> +		rc = rcfw->creq.aeq_handler(rcfw, qp_event, qp);
> +		spin_unlock(&rcfw->tbl_lock);
>   		dev_dbg(&pdev->dev, "Received QP error notification\n");
>   		dev_dbg(&pdev->dev,
>   			"qpid 0x%x, req_err=0x%x, resp_err=0x%x\n",
>   			qp_id, err_event->req_err_state_reason,
>   			err_event->res_err_state_reason);
> -		if (!qp)
> -			break;
> -		bnxt_qplib_mark_qp_error(qp);
> -		rc = rcfw->creq.aeq_handler(rcfw, qp_event, qp);
>   		break;
>   	default:
>   		/*
> diff --git a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.h b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.h
> index 45996e6..07779ae 100644
> --- a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.h
> +++ b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.h
> @@ -224,6 +224,8 @@ struct bnxt_qplib_rcfw {
>   	struct bnxt_qplib_crsqe		*crsqe_tbl;
>   	int qp_tbl_size;
>   	struct bnxt_qplib_qp_node *qp_tbl;
> +	/* To synchronize the qp-handle hash table */
> +	spinlock_t			tbl_lock;
>   	u64 oos_prev;
>   	u32 init_oos_stats;
>   	u32 cmdq_depth;