linux-kernel - Re: [PATCH v2] qla2xxx: Protect access to qpair members with qpair->qp

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Date:   Wed, 28 Jun 2017 16:33:16 +0000
From:   "Madhani, Himanshu" <Himanshu.Madhani@...ium.com>
To:     Johannes Thumshirn <jthumshirn@...e.de>
CC:     "Martin K . Petersen" <martin.petersen@...cle.com>,
        Linux SCSI Mailinglist <linux-scsi@...r.kernel.org>,
        Linux Kernel Mailinglist <linux-kernel@...r.kernel.org>,
        Dept-Eng QLA2xxx Upstream <qla2xxx-upstream@...ium.com>,
        Hannes Reinecke <hare@...e.de>,
        John Garry <john.garry@...wei.com>
Subject: Re: [PATCH v2] qla2xxx: Protect access to qpair members with
 qpair->qp_lock


> On Jun 23, 2017, at 12:10 AM, Johannes Thumshirn <jthumshirn@...e.de> wrote:
> 
> In qla2xx_start_scsi_mq() and qla2xx_dif_start_scsi_mq() we grab the
> qpair->qp_lock but do access members of the qpair before having the lock.
> Re-order the locking sequence to have all read and write access to qpair
> members under the qpair->qp_lock.
> 
> Signed-off-by: Johannes Thumshirn <jthumshirn@...e.de>
> ---
> drivers/scsi/qla2xxx/qla_iocb.c | 23 +++++++++++++----------
> 1 file changed, 13 insertions(+), 10 deletions(-)
> 
> Changes to v1:
> * Use __qla2x00_marker() instead of qla2x00_marker which is fit to be called
>  with the qp_lock held (John)
> * Don't protect qpair->online and qpair->difdix_supported as it's not
>  needed (Hannes)
> 
> diff --git a/drivers/scsi/qla2xxx/qla_iocb.c b/drivers/scsi/qla2xxx/qla_iocb.c
> index 8404f17f3c6c..c64036ddd365 100644
> --- a/drivers/scsi/qla2xxx/qla_iocb.c
> +++ b/drivers/scsi/qla2xxx/qla_iocb.c
> @@ -1770,6 +1770,9 @@ qla2xxx_start_scsi_mq(srb_t *sp)
> 	struct qla_hw_data *ha = vha->hw;
> 	struct qla_qpair *qpair = sp->qpair;
> 
> +	/* Acquire qpair specific lock */
> +	spin_lock_irqsave(&qpair->qp_lock, flags);
> +
> 	/* Setup qpair pointers */
> 	rsp = qpair->rsp;
> 	req = qpair->req;
> @@ -1779,15 +1782,14 @@ qla2xxx_start_scsi_mq(srb_t *sp)
> 
> 	/* Send marker if required */
> 	if (vha->marker_needed != 0) {
> -		if (qla2x00_marker(vha, req, rsp, 0, 0, MK_SYNC_ALL) !=
> -		    QLA_SUCCESS)
> +		if (__qla2x00_marker(vha, req, rsp, 0, 0, MK_SYNC_ALL) !=
> +		    QLA_SUCCESS) {
> +			spin_unlock_irqrestore(&qpair->qp_lock, flags);
> 			return QLA_FUNCTION_FAILED;
> +		}
> 		vha->marker_needed = 0;
> 	}
> 
> -	/* Acquire qpair specific lock */
> -	spin_lock_irqsave(&qpair->qp_lock, flags);
> -
> 	/* Check for room in outstanding command list. */
> 	handle = req->current_outstanding_cmd;
> 	for (index = 1; index < req->num_outstanding_cmds; index++) {
> @@ -1942,6 +1944,8 @@ qla2xxx_dif_start_scsi_mq(srb_t *sp)
> 			return qla2xxx_start_scsi_mq(sp);
> 	}
> 
> +	spin_lock_irqsave(&qpair->qp_lock, flags);
> +
> 	/* Setup qpair pointers */
> 	rsp = qpair->rsp;
> 	req = qpair->req;
> @@ -1951,15 +1955,14 @@ qla2xxx_dif_start_scsi_mq(srb_t *sp)
> 
> 	/* Send marker if required */
> 	if (vha->marker_needed != 0) {
> -		if (qla2x00_marker(vha, req, rsp, 0, 0, MK_SYNC_ALL) !=
> -		    QLA_SUCCESS)
> +		if (__qla2x00_marker(vha, req, rsp, 0, 0, MK_SYNC_ALL) !=
> +		    QLA_SUCCESS) {
> +			spin_unlock_irqrestore(&qpair->qp_lock, flags);
> 			return QLA_FUNCTION_FAILED;
> +		}
> 		vha->marker_needed = 0;
> 	}
> 
> -	/* Acquire ring specific lock */
> -	spin_lock_irqsave(&qpair->qp_lock, flags);
> -
> 	/* Check for room in outstanding command list. */
> 	handle = req->current_outstanding_cmd;
> 	for (index = 1; index < req->num_outstanding_cmds; index++) {
> -- 
> 2.12.3
> 

Looks Good. 

Acked-By: Himanshu Madhani <himanshu.madhani@...ium.com>