Re: [PATCH 2/4] qla2xxx: Simplify the code for aborting SCSI commands

[Himanshu Madhani <hmadhani@marvell.com>]

On 12/9/19, 12:02 PM, "linux-scsi-owner@vger.kernel.org on behalf of Bart Van Assche" <linux-scsi-owner@vger.kernel.org on behalf of bvanassche@acm.org> wrote:

    Since the SCSI core does not reuse the tag of the SCSI command that is
    being aborted by .eh_abort() before .eh_abort() has finished it is not
    necessary to check from inside that callback whether or not the SCSI command
    has already completed. Instead, rely on the firmware to return an error code
    when attempting to abort a command that has already completed. Additionally,
    rely on the firmware to return an error code when attempting to abort an
    already aborted command.
    
    In qla2x00_abort_srb(), use blk_mq_request_started() instead of
    sp->completed and sp->aborted.
    
    This patch eliminates several race conditions triggered by the removed member
    variables.
    
    Cc: Quinn Tran <qutran@marvell.com>
    Cc: Martin Wilck <mwilck@suse.com>
    Cc: Daniel Wagner <dwagner@suse.de>
    Cc: Roman Bolshakov <r.bolshakov@yadro.com>
    Signed-off-by: Bart Van Assche <bvanassche@acm.org>
    ---
     drivers/scsi/qla2xxx/qla_def.h |  3 ---
     drivers/scsi/qla2xxx/qla_isr.c |  5 -----
     drivers/scsi/qla2xxx/qla_os.c  | 15 ++-------------
     3 files changed, 2 insertions(+), 21 deletions(-)
    
    diff --git a/drivers/scsi/qla2xxx/qla_def.h b/drivers/scsi/qla2xxx/qla_def.h
    index 460f443f6471..ab7424318ee8 100644
    --- a/drivers/scsi/qla2xxx/qla_def.h
    +++ b/drivers/scsi/qla2xxx/qla_def.h
    @@ -597,9 +597,6 @@ typedef struct srb {
     	struct fc_port *fcport;
     	struct scsi_qla_host *vha;
     	unsigned int start_timer:1;
    -	unsigned int abort:1;
    -	unsigned int aborted:1;
    -	unsigned int completed:1;
     
     	uint32_t handle;
     	uint16_t flags;
    diff --git a/drivers/scsi/qla2xxx/qla_isr.c b/drivers/scsi/qla2xxx/qla_isr.c
    index 2601d7673c37..721a8d83e350 100644
    --- a/drivers/scsi/qla2xxx/qla_isr.c
    +++ b/drivers/scsi/qla2xxx/qla_isr.c
    @@ -2487,11 +2487,6 @@ qla2x00_status_entry(scsi_qla_host_t *vha, struct rsp_que *rsp, void *pkt)
     		return;
     	}
     
    -	if (sp->abort)
    -		sp->aborted = 1;
    -	else
    -		sp->completed = 1;
    -
     	if (sp->cmd_type != TYPE_SRB) {
     		req->outstanding_cmds[handle] = NULL;
     		ql_dbg(ql_dbg_io, vha, 0x3015,
    diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
    index 145ea93206f0..2231d99d311b 100644
    --- a/drivers/scsi/qla2xxx/qla_os.c
    +++ b/drivers/scsi/qla2xxx/qla_os.c
    @@ -1253,17 +1253,6 @@ qla2xxx_eh_abort(struct scsi_cmnd *cmd)
     		return SUCCESS;
     
     	spin_lock_irqsave(qpair->qp_lock_ptr, flags);
    -	if (sp->completed) {
    -		spin_unlock_irqrestore(qpair->qp_lock_ptr, flags);
    -		return SUCCESS;
    -	}
    -
    -	if (sp->abort || sp->aborted) {
    -		spin_unlock_irqrestore(qpair->qp_lock_ptr, flags);
    -		return FAILED;
    -	}
    -
    -	sp->abort = 1;
     	sp->comp = &comp;
     	spin_unlock_irqrestore(qpair->qp_lock_ptr, flags);
     
    @@ -1696,6 +1685,7 @@ static void qla2x00_abort_srb(struct qla_qpair *qp, srb_t *sp, const int res,
     	DECLARE_COMPLETION_ONSTACK(comp);
     	scsi_qla_host_t *vha = qp->vha;
     	struct qla_hw_data *ha = vha->hw;
    +	struct scsi_cmnd *cmd = GET_CMD_SP(sp);
     	int rval;
     	bool ret_cmd;
     	uint32_t ratov_j;
    @@ -1717,7 +1707,6 @@ static void qla2x00_abort_srb(struct qla_qpair *qp, srb_t *sp, const int res,
     		}
     
     		sp->comp = &comp;
    -		sp->abort =  1;
     		spin_unlock_irqrestore(qp->qp_lock_ptr, *flags);
     
     		rval = ha->isp_ops->abort_command(sp);
    @@ -1741,7 +1730,7 @@ static void qla2x00_abort_srb(struct qla_qpair *qp, srb_t *sp, const int res,
     		}
     
     		spin_lock_irqsave(qp->qp_lock_ptr, *flags);
    -		if (ret_cmd && (!sp->completed || !sp->aborted))
    +		if (ret_cmd && blk_mq_request_started(cmd->request))
     			sp->done(sp, res);
     	} else {
     		sp->done(sp, res);
    
Acked-By: Himanshu Madhani <hmadhani@marvell.com>