sfc: Read VPD with pci_vpd_alloc()

Use pci_vpd_alloc() to dynamically allocate a properly sized buffer and
read the full VPD data into it.

This avoids having to allocate a buffer on the stack, and we don't have to
make any assumptions on VPD size and location of information in VPD.

Link: https://lore.kernel.org/r/e58f1e40-c043-0266-9a0f-e5a7f3f6883c@gmail.com
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/net/ethernet/sfc/efx.c

@@ -900,21 +900,18 @@ static void efx_pci_remove(struct pci_dev *pci_dev)
 
 /* NIC VPD information
  * Called during probe to display the part number of the
- * installed NIC.  VPD is potentially very large but this should
- * always appear within the first 512 bytes.
+ * installed NIC.
  */
-#define SFC_VPD_LEN 512
 static void efx_probe_vpd_strings(struct efx_nic *efx)
 {
 	struct pci_dev *dev = efx->pci_dev;
-	char vpd_data[SFC_VPD_LEN];
-	ssize_t vpd_size;
 	int ro_start, ro_size, i, j;
+	unsigned int vpd_size;
+	u8 *vpd_data;
 
-	/* Get the vpd data from the device */
-	vpd_size = pci_read_vpd(dev, 0, sizeof(vpd_data), vpd_data);
-	if (vpd_size <= 0) {
-		netif_err(efx, drv, efx->net_dev, "Unable to read VPD\n");
+	vpd_data = pci_vpd_alloc(dev, &vpd_size);
+	if (IS_ERR(vpd_data)) {
+		pci_warn(dev, "Unable to read VPD\n");
 		return;
 	}
 
@@ -922,7 +919,7 @@ static void efx_probe_vpd_strings(struct efx_nic *efx)
 	ro_start = pci_vpd_find_tag(vpd_data, vpd_size, PCI_VPD_LRDT_RO_DATA);
 	if (ro_start < 0) {
 		netif_err(efx, drv, efx->net_dev, "VPD Read-only not found\n");
-		return;
+		goto out;
 	}
 
 	ro_size = pci_vpd_lrdt_size(&vpd_data[ro_start]);
@@ -935,14 +932,14 @@ static void efx_probe_vpd_strings(struct efx_nic *efx)
 	i = pci_vpd_find_info_keyword(vpd_data, i, j, "PN");
 	if (i < 0) {
 		netif_err(efx, drv, efx->net_dev, "Part number not found\n");
-		return;
+		goto out;
 	}
 
 	j = pci_vpd_info_field_size(&vpd_data[i]);
 	i += PCI_VPD_INFO_FLD_HDR_SIZE;
 	if (i + j > vpd_size) {
 		netif_err(efx, drv, efx->net_dev, "Incomplete part number\n");
-		return;
+		goto out;
 	}
 
 	netif_info(efx, drv, efx->net_dev,
@@ -953,21 +950,23 @@ static void efx_probe_vpd_strings(struct efx_nic *efx)
 	i = pci_vpd_find_info_keyword(vpd_data, i, j, "SN");
 	if (i < 0) {
 		netif_err(efx, drv, efx->net_dev, "Serial number not found\n");
-		return;
+		goto out;
 	}
 
 	j = pci_vpd_info_field_size(&vpd_data[i]);
 	i += PCI_VPD_INFO_FLD_HDR_SIZE;
 	if (i + j > vpd_size) {
 		netif_err(efx, drv, efx->net_dev, "Incomplete serial number\n");
-		return;
+		goto out;
 	}
 
 	efx->vpd_sn = kmalloc(j + 1, GFP_KERNEL);
 	if (!efx->vpd_sn)
-		return;
+		goto out;
 
 	snprintf(efx->vpd_sn, j + 1, "%s", &vpd_data[i]);
+out:
+	kfree(vpd_data);
 }