scsi: lpfc: devloss timeout race condition caused null pointer reference

A race condition between the context of devloss timeout handler and I/O
completion caused devloss timeout handler de-referencing pointer that had
been released.

Added the check in lpfc_sli_validate_fcp_iocb() on LPFC_IO_ON_TXCMPLQ to
capture the race condition of I/O completion and devloss timeout handler
attemption for aborting the I/O. Also, added check on lpfc_cmd->rdata
pointer before de-referenceing lpfc_cmd->rdata->pnode.

Also, added protection in lpfc_sli_abort_iocb() routine on driver performed
FCP I/O FLUSHING already under way before proceeding to aborting I/Os.

Signed-off-by: Dick Kennedy <[e-mail]>
Signed-off-by: James Smart <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/lpfc/lpfc_scsi.c

···
 	int err;
 
 	rdata = lpfc_rport_data_from_scsi_device(cmnd->device);
+
+	/* sanity check on references */
+	if (unlikely(!rdata) || unlikely(!rport))
+		goto out_fail_command;
+
 	err = fc_remote_port_chkready(rport);
 	if (err) {
 		cmnd->result = err;

drivers/scsi/lpfc/lpfc_sli.c

···
 	struct lpfc_scsi_buf *lpfc_cmd;
 	int rc = 1;
 
-	if (!(iocbq->iocb_flag &  LPFC_IO_FCP))
+	if (iocbq->vport != vport)
 		return rc;
 
-	if (iocbq->vport != vport)
+	if (!(iocbq->iocb_flag &  LPFC_IO_FCP) ||
+	    !(iocbq->iocb_flag & LPFC_IO_ON_TXCMPLQ))
 		return rc;
 
 	lpfc_cmd = container_of(iocbq, struct lpfc_scsi_buf, cur_iocbq);
···
 
 	switch (ctx_cmd) {
 	case LPFC_CTX_LUN:
-		if ((lpfc_cmd->rdata->pnode) &&
+		if ((lpfc_cmd->rdata) && (lpfc_cmd->rdata->pnode) &&
 		    (lpfc_cmd->rdata->pnode->nlp_sid == tgt_id) &&
 		    (scsilun_to_int(&lpfc_cmd->fcp_cmnd->fcp_lun) == lun_id))
 			rc = 0;
 		break;
 	case LPFC_CTX_TGT:
-		if ((lpfc_cmd->rdata->pnode) &&
+		if ((lpfc_cmd->rdata) && (lpfc_cmd->rdata->pnode) &&
 		    (lpfc_cmd->rdata->pnode->nlp_sid == tgt_id))
 			rc = 0;
 		break;
···
 	IOCB_t *cmd = NULL;
 	int errcnt = 0, ret_val = 0;
 	int i;
+
+	/* all I/Os are in process of being flushed */
+	if (phba->hba_flag & HBA_FCP_IOQ_FLUSH)
+		return errcnt;
 
 	for (i = 1; i <= phba->sli.last_iotag; i++) {
 		iocbq = phba->sli.iocbq_lookup[i];