x86: corruption check: run the corruption checks from a work queue

Impact: change the implementation of the debug feature

the periodic corruption checks are better off run from a work queue; there's
nothing time critical about them and this way the amount of
interrupt-context work is reduced.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/check.c

 #include <linux/module.h>
 #include <linux/sched.h>
-
+#include <linux/kthread.h>
+#include <linux/workqueue.h>
 #include <asm/e820.h>
 #include <asm/proto.h>
 
@@ -108,13 +109,14 @@ void __init setup_bios_corruption_check(void)
 	update_e820();
 }
 
-static struct timer_list periodic_check_timer;
 
 void check_for_bios_corruption(void)
 {
 	int i;
 	int corruption = 0;
 
+	printk("dot\n");
+
 	if (!memory_corruption_check)
 		return;
 
@@ -135,24 +137,29 @@ void check_for_bios_corruption(void)
 	WARN(corruption, KERN_ERR "Memory corruption detected in low memory\n");
 }
 
-static void periodic_check_for_corruption(unsigned long data)
+static void check_corruption(struct work_struct *dummy);
+static DECLARE_DELAYED_WORK(bios_check_work, check_corruption);
+
+static void check_corruption(struct work_struct *dummy)
 {
 	check_for_bios_corruption();
-	mod_timer(&periodic_check_timer,
-		round_jiffies(jiffies + corruption_check_period*HZ));
+	schedule_delayed_work(&bios_check_work,
+		round_jiffies_relative(corruption_check_period*HZ)); 
 }
 
-void start_periodic_check_for_corruption(void)
+static int start_periodic_check_for_corruption(void)
 {
 	if (!memory_corruption_check || corruption_check_period == 0)
-		return;
+		return 0;
 
 	printk(KERN_INFO "Scanning for low memory corruption every %d seconds\n",
 	       corruption_check_period);
 
-	init_timer(&periodic_check_timer);
-	periodic_check_timer.function = &periodic_check_for_corruption;
-	periodic_check_for_corruption(0);
+	/* First time we run the checks right away */
+	schedule_delayed_work(&bios_check_work, 0);
+	return 0;
 }
+
+module_init(start_periodic_check_for_corruption);
 #endif
 

arch/x86/mm/init_32.c

@@ -970,8 +970,6 @@ void __init mem_init(void)
 	int codesize, reservedpages, datasize, initsize;
 	int tmp;
 
-	start_periodic_check_for_corruption();
-
 #ifdef CONFIG_FLATMEM
 	BUG_ON(!mem_map);
 #endif

arch/x86/mm/init_64.c

@@ -879,8 +879,6 @@ void __init mem_init(void)
 {
 	long codesize, reservedpages, datasize, initsize;
 
-	start_periodic_check_for_corruption();
-
 	pci_iommu_alloc();
 
 	/* clear_bss() already clear the empty_zero_page */