scsi: lpfc: Fix lpfc_nodelist leak when processing unsolicited event

In order to create or activate a new node, lpfc_els_unsol_buffer() invokes
lpfc_nlp_init() or lpfc_enable_node() or lpfc_nlp_get(), all of them will
return a reference of the specified lpfc_nodelist object to "ndlp" with
increased refcnt.

When lpfc_els_unsol_buffer() returns, local variable "ndlp" becomes
invalid, so the refcount should be decreased to keep refcount balanced.

The reference counting issue happens in one exception handling path of
lpfc_els_unsol_buffer(). When "ndlp" in DEV_LOSS, the function forgets to
decrease the refcnt increased by lpfc_nlp_init() or lpfc_enable_node() or
lpfc_nlp_get(), causing a refcnt leak.

Fix this issue by calling lpfc_nlp_put() when "ndlp" in DEV_LOSS.

Link: https://lore.kernel.org/r/1590416184-52592-1-git-send-email-xiyuyang19@fudan.edu.cnReviewed-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc_els.c

@@ -8508,6 +8508,8 @@ lpfc_els_unsol_buffer(struct lpfc_hba *phba, struct lpfc_sli_ring *pring,
 	spin_lock_irq(shost->host_lock);
 	if (ndlp->nlp_flag & NLP_IN_DEV_LOSS) {
 		spin_unlock_irq(shost->host_lock);
+		if (newnode)
+			lpfc_nlp_put(ndlp);
 		goto dropit;
 	}
 	spin_unlock_irq(shost->host_lock);