[PNP]: Disable resources fix

Some PnPBIOSes do not follow the specifications with regard to
disabling devices.  This patch preserves the tag bits, while zeroing
the resource settings.  Previously we would zero the entire buffer.
It has been tested and appears to correct the issue while remaining
compatible with unbroken PnPBIOSes.

drivers/pnp/pnpbios/core.c

@@ -264,19 +264,49 @@ static int pnpbios_set_resources(struct pnp_dev * dev, struct pnp_resource_table
 	return ret;
 }
 
+static void pnpbios_zero_data_stream(struct pnp_bios_node * node)
+{
+	unsigned char * p = (char *)node->data;
+	unsigned char * end = (char *)(node->data + node->size);
+	unsigned int len;
+	int i;
+	while ((char *)p < (char *)end) {
+		if(p[0] & 0x80) { /* large tag */
+			len = (p[2] << 8) | p[1];
+			p += 3;
+		} else {
+			if (((p[0]>>3) & 0x0f) == 0x0f)
+				return;
+			len = p[0] & 0x07;
+			p += 1;
+		}
+		for (i = 0; i < len; i++)
+			p[i] = 0;
+		p += len;
+	}
+	printk(KERN_ERR "PnPBIOS: Resource structure did not contain an end tag.\n");
+}
+
 static int pnpbios_disable_resources(struct pnp_dev *dev)
 {
 	struct pnp_bios_node * node;
+	u8 nodenum = dev->number;
 	int ret;
 
 	/* just in case */
 	if(dev->flags & PNPBIOS_NO_DISABLE || !pnpbios_is_dynamic(dev))
 		return -EPERM;
 
-	/* the value of this will be zero */
 	node = pnpbios_kmalloc(node_info.max_node_size, GFP_KERNEL);
 	if (!node)
 		return -ENOMEM;
+
+	if (pnp_bios_get_dev_node(&nodenum, (char )PNPMODE_DYNAMIC, node)) {
+		kfree(node);
+		return -ENODEV;
+	}
+	pnpbios_zero_data_stream(node);
+
 	ret = pnp_bios_set_dev_node(dev->number, (char)PNPMODE_DYNAMIC, node);
 	kfree(node);
 	if (ret > 0)