[PATCH] Fix timeout overflow with jiffies
Ingo Molnar [Fri, 16 Feb 2007 09:27:29 +0000 (01:27 -0800)]
Prevent timeout overflow if timer ticks are behind jiffies (due to high
softirq load or due to dyntick), by limiting the valid timeout range to
MAX_LONG/2.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/jiffies.h

index 9243cef..c080f61 100644 (file)
@@ -142,13 +142,13 @@ static inline u64 get_jiffies_64(void)
  *
  * And some not so obvious.
  *
- * Note that we don't want to return MAX_LONG, because
+ * Note that we don't want to return LONG_MAX, because
  * for various timeout reasons we often end up having
  * to wait "jiffies+1" in order to guarantee that we wait
  * at _least_ "jiffies" - so "jiffies+1" had better still
  * be positive.
  */
-#define MAX_JIFFY_OFFSET ((~0UL >> 1)-1)
+#define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1)
 
 /*
  * We want to do realistic conversions of time so we need to use the same