sysctl: add proc_do_large_bitmap

[safe/jmp/linux-2.6] / kernel / time / clocksource.c

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 08adacb..1f5dde6 100644 (file)
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -343,7 +343,19 @@ static void clocksource_resume_watchdog(void)
 {
        unsigned long flags;
 
-       spin_lock_irqsave(&watchdog_lock, flags);
+       /*
+        * We use trylock here to avoid a potential dead lock when
+        * kgdb calls this code after the kernel has been stopped with
+        * watchdog_lock held. When watchdog_lock is held we just
+        * return and accept, that the watchdog might trigger and mark
+        * the monitored clock source (usually TSC) unstable.
+        *
+        * This does not affect the other caller clocksource_resume()
+        * because at this point the kernel is UP, interrupts are
+        * disabled and nothing can hold watchdog_lock.
+        */
+       if (!spin_trylock_irqsave(&watchdog_lock, flags))
+               return;
        clocksource_reset_watchdog();
        spin_unlock_irqrestore(&watchdog_lock, flags);
 }
@@ -441,6 +453,18 @@ static inline int clocksource_watchdog_kthread(void *data) { return 0; }
 #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */
 
 /**
+ * clocksource_suspend - suspend the clocksource(s)
+ */
+void clocksource_suspend(void)
+{
+       struct clocksource *cs;
+
+       list_for_each_entry_reverse(cs, &clocksource_list, list)
+               if (cs->suspend)
+                       cs->suspend(cs);
+}
+
+/**
  * clocksource_resume - resume the clocksource(s)
  */
 void clocksource_resume(void)
@@ -458,8 +482,8 @@ void clocksource_resume(void)
  * clocksource_touch_watchdog - Update watchdog
  *
  * Update the watchdog after exception contexts such as kgdb so as not
- * to incorrectly trip the watchdog.
- *
+ * to incorrectly trip the watchdog. This might fail when the kernel
+ * was stopped in code which holds watchdog_lock.
  */
 void clocksource_touch_watchdog(void)
 {
@@ -568,6 +592,10 @@ static inline void clocksource_select(void) { }
  */
 static int __init clocksource_done_booting(void)
 {
+       mutex_lock(&clocksource_mutex);
+       curr_clocksource = clocksource_default_clock();
+       mutex_unlock(&clocksource_mutex);
+
        finished_booting = 1;
 
        /*