[PATCH 45/59] qla2xxx: Fix a race condition between aborting and completing a SCSI command

[Bart Van Assche <bvanassche@xxxxxxx>]

Instead of allocating a struct srb dynamically from inside .queuecommand(),
set qla2xxx_driver_template.cmd_size such that struct scsi_cmnd and struct
srb are contiguous. Do not call QLA_QPAIR_MARK_BUSY() /
QLA_QPAIR_MARK_NOT_BUSY() for SRBs associated with SCSI commands. That is
safe because scsi_remove_host() is called before queue pairs are deleted
and scsi_remove_host() waits for all outstanding SCSI commands to finish.

Cc: Himanshu Madhani <hmadhani@xxxxxxxxxxx>
Cc: Giridhar Malavali <gmalavali@xxxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
 drivers/scsi/qla2xxx/qla_def.h |  1 -
 drivers/scsi/qla2xxx/qla_os.c  | 46 +++++++---------------------------
 2 files changed, 9 insertions(+), 38 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_def.h b/drivers/scsi/qla2xxx/qla_def.h
index 65d79bcb7ccf..3ffe7661a25b 100644
--- a/drivers/scsi/qla2xxx/qla_def.h
+++ b/drivers/scsi/qla2xxx/qla_def.h
@@ -630,7 +630,6 @@ typedef struct srb {
 } srb_t;
 
 #define GET_CMD_SP(sp) (sp->u.scmd.cmd)
-#define SET_CMD_SP(sp, cmd) (sp->u.scmd.cmd = cmd)
 #define GET_CMD_CTX_SP(sp) (sp->u.scmd.ctx)
 
 #define GET_CMD_SENSE_LEN(sp) \
diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
index 0b7d4092ea31..835572d7d71a 100644
--- a/drivers/scsi/qla2xxx/qla_os.c
+++ b/drivers/scsi/qla2xxx/qla_os.c
@@ -713,7 +713,6 @@ void qla2x00_sp_compl(srb_t *sp, int res)
 	cmd->scsi_done(cmd);
 	if (comp)
 		complete(comp);
-	qla2x00_rel_sp(sp);
 }
 
 void qla2xxx_qpair_sp_free_dma(srb_t *sp)
@@ -814,7 +813,6 @@ void qla2xxx_qpair_sp_compl(srb_t *sp, int res)
 	cmd->scsi_done(cmd);
 	if (comp)
 		complete(comp);
-	qla2xxx_rel_qpair_sp(sp->qpair, sp);
 }
 
 static int
@@ -908,9 +906,8 @@ qla2xxx_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 	else
 		goto qc24_target_busy;
 
-	sp = qla2x00_get_sp(vha, fcport, GFP_ATOMIC);
-	if (!sp)
-		goto qc24_host_busy;
+	sp = scsi_cmd_priv(cmd);
+	qla2xxx_init_sp(sp, vha, vha->hw->base_qpair, fcport);
 
 	sp->u.scmd.cmd = cmd;
 	sp->type = SRB_SCSI_CMD;
@@ -931,9 +928,6 @@ qla2xxx_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 qc24_host_busy_free_sp:
 	sp->free(sp);
 
-qc24_host_busy:
-	return SCSI_MLQUEUE_HOST_BUSY;
-
 qc24_target_busy:
 	return SCSI_MLQUEUE_TARGET_BUSY;
 
@@ -994,9 +988,8 @@ qla2xxx_mqueuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd,
 	else
 		goto qc24_target_busy;
 
-	sp = qla2xxx_get_qpair_sp(vha, qpair, fcport, GFP_ATOMIC);
-	if (!sp)
-		goto qc24_host_busy;
+	sp = scsi_cmd_priv(cmd);
+	qla2xxx_init_sp(sp, vha, qpair, fcport);
 
 	sp->u.scmd.cmd = cmd;
 	sp->type = SRB_SCSI_CMD;
@@ -1020,9 +1013,6 @@ qla2xxx_mqueuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd,
 qc24_host_busy_free_sp:
 	sp->free(sp);
 
-qc24_host_busy:
-	return SCSI_MLQUEUE_HOST_BUSY;
-
 qc24_target_busy:
 	return SCSI_MLQUEUE_TARGET_BUSY;
 
@@ -1257,10 +1247,8 @@ qla2xxx_eh_abort(struct scsi_cmnd *cmd)
 	int ret;
 	unsigned int id;
 	uint64_t lun;
-	unsigned long flags;
 	int rval;
 	struct qla_hw_data *ha = vha->hw;
-	struct qla_qpair *qpair;
 
 	if (qla2x00_isp_reg_stat(ha)) {
 		ql_log(ql_log_info, vha, 0x8042,
@@ -1272,32 +1260,14 @@ qla2xxx_eh_abort(struct scsi_cmnd *cmd)
 	if (ret != 0)
 		return ret;
 
-	sp = (srb_t *) CMD_SP(cmd);
-	if (!sp)
-		return SUCCESS;
-
-	qpair = sp->qpair;
-	if (!qpair)
-		return SUCCESS;
+	sp = scsi_cmd_priv(cmd);
 
 	if (sp->fcport && sp->fcport->deleted)
 		return SUCCESS;
 
-	spin_lock_irqsave(qpair->qp_lock_ptr, flags);
-	if (sp->type != SRB_SCSI_CMD || GET_CMD_SP(sp) != cmd) {
-		/* there's a chance an interrupt could clear
-		   the ptr as part of done & free */
-		spin_unlock_irqrestore(qpair->qp_lock_ptr, flags);
-		return SUCCESS;
-	}
-
-	/* Get a reference to the sp and drop the lock. */
-	if (sp_get(sp)){
-		/* ref_count is already 0 */
-		spin_unlock_irqrestore(qpair->qp_lock_ptr, flags);
+	/* Return if the command has already finished. */
+	if (sp_get(sp))
 		return SUCCESS;
-	}
-	spin_unlock_irqrestore(qpair->qp_lock_ptr, flags);
 
 	id = cmd->device->id;
 	lun = cmd->device->lun;
@@ -1325,6 +1295,7 @@ qla2xxx_eh_abort(struct scsi_cmnd *cmd)
 		uint32_t ratov = ha->r_a_tov/10;
 		uint32_t ratov_j = msecs_to_jiffies(4 * ratov * 1000);
 
+		WARN_ON_ONCE(sp->comp);
 		sp->comp = &comp;
 		if (!wait_for_completion_timeout(&comp, ratov_j)) {
 			ql_dbg(ql_dbg_taskm, vha, 0xffff,
@@ -7151,6 +7122,7 @@ struct scsi_host_template qla2xxx_driver_template = {
 
 	.supported_mode		= MODE_INITIATOR,
 	.track_queue_depth	= 1,
+	.cmd_size		= sizeof(srb_t),
 };
 
 static const struct pci_error_handlers qla2xxx_err_handler = {
-- 
2.22.0.770.g0f2c4a37fd-goog