[PATCH v2 2/6] qla2xxx: Simplify the code for aborting SCSI commands

[Bart Van Assche <bvanassche@acm.org>]

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.

Acked-by: Himanshu Madhani <hmadhani@marvell.com>
Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Cc: Quinn Tran <qutran@marvell.com>
Cc: Martin Wilck <mwilck@suse.com>
Cc: Daniel Wagner <dwagner@suse.de>
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  | 27 ++++++++++++++-------------
 3 files changed, 14 insertions(+), 21 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_def.h b/drivers/scsi/qla2xxx/qla_def.h
index ed32e9715794..c5a067f45005 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 e7bad0bfffda..0c9bfe77ba8a 100644
--- a/drivers/scsi/qla2xxx/qla_isr.c
+++ b/drivers/scsi/qla2xxx/qla_isr.c
@@ -2504,11 +2504,6 @@ 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 79387ac8936f..a34f27b2d602 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);
 
@@ -1688,6 +1677,10 @@ qla2x00_loop_reset(scsi_qla_host_t *vha)
 	return QLA_SUCCESS;
 }
 
+/*
+ * The caller must ensure that no completion interrupts will happen
+ * while this function is in progress.
+ */
 static void qla2x00_abort_srb(struct qla_qpair *qp, srb_t *sp, const int res,
 			      unsigned long *flags)
 	__releases(qp->qp_lock_ptr)
@@ -1696,6 +1689,7 @@ 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 +1711,6 @@ 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);
@@ -1741,13 +1734,17 @@ 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);
 	}
 }
 
+/*
+ * The caller must ensure that no completion interrupts will happen
+ * while this function is in progress.
+ */
 static void
 __qla2x00_abort_all_cmds(struct qla_qpair *qp, int res)
 {
@@ -1794,6 +1791,10 @@ __qla2x00_abort_all_cmds(struct qla_qpair *qp, int res)
 	spin_unlock_irqrestore(qp->qp_lock_ptr, flags);
 }
 
+/*
+ * The caller must ensure that no completion interrupts will happen
+ * while this function is in progress.
+ */
 void
 qla2x00_abort_all_cmds(scsi_qla_host_t *vha, int res)
 {