scsi: lpfc: Fix panic if driver unloaded when port is offline

System crashes when the lpfc module is unloaded after making the port
offline

The nvme queue pointers were freed during port offline, but were later
accessed in pci remove path.

Validate the pointers in pci remove path before accessing them.
Signed-off-by: NDick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: NJames Smart <james.smart@broadcom.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc_nvme.c

@@ -2970,7 +2970,7 @@ lpfc_nvme_wait_for_io_drain(struct lpfc_hba *phba)
 	struct lpfc_sli_ring  *pring;
 	u32 i, wait_cnt = 0;
 
-	if (phba->sli_rev < LPFC_SLI_REV4)
+	if (phba->sli_rev < LPFC_SLI_REV4 || !phba->sli4_hba.nvme_wq)
 		return;
 
 	/* Cycle through all NVME rings and make sure all outstanding
@@ -2979,6 +2979,9 @@ lpfc_nvme_wait_for_io_drain(struct lpfc_hba *phba)
 	for (i = 0; i < phba->cfg_nvme_io_channel; i++) {
 		pring = phba->sli4_hba.nvme_wq[i]->pring;
 
+		if (!pring)
+			continue;
+
 		/* Retrieve everything on the txcmplq */
 		while (!list_empty(&pring->txcmplq)) {
 			msleep(LPFC_XRI_EXCH_BUSY_WAIT_T1);