scsi: lpfc: Avoid NULL pointer dereference in lpfc_els_abort()

We might have a NULL pring in lpfc_els_abort(), for example on error
recovery path, since queues are destroyed during error recovery
mechanism.

In this case, we should just drop the abort since the queues will be
recreated anyway. This patch just verifies for NULL pointer and stop the
abortion of the queue in case of a NULL pring.

Also, this patch converts return type of lpfc_els_abort() from int to
void, since it's not checked anywhere.
Reported-by: Harsha Thyagaraja <hathyaga@in.ibm.com>
Reported-by: Naresh Bannoth <nbannoth@in.ibm.com>
Tested-by: Raphael Silva <raphasil@linux.vnet.ibm.com>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Acked-by: James Smart  <james.smart@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc_crtn.h

@@ -127,7 +127,7 @@ int lpfc_disc_state_machine(struct lpfc_vport *, struct lpfc_nodelist *, void *,
 void lpfc_do_scr_ns_plogi(struct lpfc_hba *, struct lpfc_vport *);
 int lpfc_check_sparm(struct lpfc_vport *, struct lpfc_nodelist *,
 		     struct serv_parm *, uint32_t, int);
-int lpfc_els_abort(struct lpfc_hba *, struct lpfc_nodelist *);
+void lpfc_els_abort(struct lpfc_hba *, struct lpfc_nodelist *);
 void lpfc_more_plogi(struct lpfc_vport *);
 void lpfc_more_adisc(struct lpfc_vport *);
 void lpfc_end_rscn(struct lpfc_vport *);

drivers/scsi/lpfc/lpfc_nportdisc.c

@@ -206,7 +206,7 @@ lpfc_check_elscmpl_iocb(struct lpfc_hba *phba, struct lpfc_iocbq *cmdiocb,
  * associated with a LPFC_NODELIST entry. This
  * routine effectively results in a "software abort".
  */
-int
+void
 lpfc_els_abort(struct lpfc_hba *phba, struct lpfc_nodelist *ndlp)
 {
 	LIST_HEAD(abort_list);
@@ -215,6 +215,10 @@ lpfc_els_abort(struct lpfc_hba *phba, struct lpfc_nodelist *ndlp)
 
 	pring = lpfc_phba_elsring(phba);
 
+	/* In case of error recovery path, we might have a NULL pring here */
+	if (!pring)
+		return;
+
 	/* Abort outstanding I/O on NPort <nlp_DID> */
 	lpfc_printf_vlog(ndlp->vport, KERN_INFO, LOG_DISCOVERY,
 			 "2819 Abort outstanding I/O on NPort x%x "
@@ -273,7 +277,6 @@ lpfc_els_abort(struct lpfc_hba *phba, struct lpfc_nodelist *ndlp)
 			      IOSTAT_LOCAL_REJECT, IOERR_SLI_ABORTED);
 
 	lpfc_cancel_retry_delay_tmo(phba->pport, ndlp);
-	return 0;
 }
 
 static int