x86: Don't check for BIOS corruption in first 64K when there's no need to

Due to commit 781c5a67f152c17c3e4a9ed9647f8c0be6ea5ae9 it is
likely that the number of areas to scan for BIOS corruption is 0
 -- especially when the first 64K is already reserved
(X86_RESERVE_LOW is 64K by default).

If that's the case then don't set up the scan.

Signed-off-by: Naga Chumbalkar <nagananda.chumbalkar@hp.com>
Cc: <stable@kernel.org>
LKML-Reference: <20110225202838.2229.71011.sendpatchset@nchumbalkar.americas.hpqcorp.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/check.c

@@ -106,8 +106,8 @@ void __init setup_bios_corruption_check(void)
 		addr += size;
 	}
 
-	printk(KERN_INFO "Scanning %d areas for low memory corruption\n",
-	       num_scan_areas);
+	if (num_scan_areas)
+		printk(KERN_INFO "Scanning %d areas for low memory corruption\n", num_scan_areas);
 }
 
 
@@ -143,12 +143,12 @@ static void check_corruption(struct work_struct *dummy)
 {
 	check_for_bios_corruption();
 	schedule_delayed_work(&bios_check_work,
-		round_jiffies_relative(corruption_check_period*HZ)); 
+		round_jiffies_relative(corruption_check_period*HZ));
 }
 
 static int start_periodic_check_for_corruption(void)
 {
-	if (!memory_corruption_check || corruption_check_period == 0)
+	if (!num_scan_areas || !memory_corruption_check || corruption_check_period == 0)
 		return 0;
 
 	printk(KERN_INFO "Scanning for low memory corruption every %d seconds\n",