bnxt_en: Do not treat DSN (Digital Serial Number) read failure as fatal.

DSN read can fail, for example on a kdump kernel without PCIe extended
config space support.  If DSN read fails, don't set the
BNXT_FLAG_DSN_VALID flag and continue loading.  Check the flag
to see if the stored DSN is valid before using it.  Only VF reps
creation should fail without valid DSN.

Fixes: 03213a99 ("bnxt: move bp->switch_id initialization to PF probe")
Reported-by: Marc Smith <msmith626@gmail.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -11373,7 +11373,7 @@ int bnxt_get_port_parent_id(struct net_device *dev,
 		return -EOPNOTSUPP;
 
 	/* The PF and it's VF-reps only support the switchdev framework */
-	if (!BNXT_PF(bp))
+	if (!BNXT_PF(bp) || !(bp->flags & BNXT_FLAG_DSN_VALID))
 		return -EOPNOTSUPP;
 
 	ppid->id_len = sizeof(bp->switch_id);
@@ -11746,6 +11746,7 @@ static int bnxt_pcie_dsn_get(struct bnxt *bp, u8 dsn[])
 	put_unaligned_le32(dw, &dsn[0]);
 	pci_read_config_dword(pdev, pos + 4, &dw);
 	put_unaligned_le32(dw, &dsn[4]);
+	bp->flags |= BNXT_FLAG_DSN_VALID;
 	return 0;
 }
 
@@ -11857,9 +11858,7 @@ static int bnxt_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	if (BNXT_PF(bp)) {
 		/* Read the adapter's DSN to use as the eswitch switch_id */
-		rc = bnxt_pcie_dsn_get(bp, bp->switch_id);
-		if (rc)
-			goto init_err_pci_clean;
+		bnxt_pcie_dsn_get(bp, bp->switch_id);
 	}
 
 	/* MTU range: 60 - FW defined max */

drivers/net/ethernet/broadcom/bnxt/bnxt.h

@@ -1532,6 +1532,7 @@ struct bnxt {
 	#define BNXT_FLAG_NO_AGG_RINGS	0x20000
 	#define BNXT_FLAG_RX_PAGE_MODE	0x40000
 	#define BNXT_FLAG_MULTI_HOST	0x100000
+	#define BNXT_FLAG_DSN_VALID	0x200000
 	#define BNXT_FLAG_DOUBLE_DB	0x400000
 	#define BNXT_FLAG_CHIP_NITRO_A0	0x1000000
 	#define BNXT_FLAG_DIM		0x2000000

drivers/net/ethernet/broadcom/bnxt/bnxt_vfr.c

@@ -398,6 +398,9 @@ static int bnxt_vf_reps_create(struct bnxt *bp)
 	struct net_device *dev;
 	int rc, i;
 
+	if (!(bp->flags & BNXT_FLAG_DSN_VALID))
+		return -ENODEV;
+
 	bp->vf_reps = kcalloc(num_vfs, sizeof(vf_rep), GFP_KERNEL);
 	if (!bp->vf_reps)
 		return -ENOMEM;