timers: Fix endless looping between cascade() and internal_add_timer()
Adding two (or more) timers with large values for "expires" (they have
to reside within tv5 in the same list) leads to endless looping
between cascade() and internal_add_timer() in case CONFIG_BASE_SMALL
is one and jiffies are crossing the value 1 << 18. The bug was
introduced between 2.6.11 and 2.6.12 (and survived for quite some
time).
This patch ensures that when cascade() is called timers within tv5 are
not added endlessly to their own list again, instead they are added to
the next lower tv level tv4 (as expected).
Change-Id: Ia4e9b79767a4d255f676ecbb739b537bbe7033af
Signed-off-by: Christian Hildner <christian.hildner@siemens.com>
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Link: http://lkml.kernel.org/r/98673C87CB31274881CFFE0B65ECC87B0F5FC1963E@DEFTHW99EA4MSX.ww902.siemens.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
diff --git a/kernel/timer.c b/kernel/timer.c
index 24c5d20..ef5ec26 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -63,6 +63,7 @@
#define TVR_SIZE (1 << TVR_BITS)
#define TVN_MASK (TVN_SIZE - 1)
#define TVR_MASK (TVR_SIZE - 1)
+#define MAX_TVAL ((unsigned long)((1ULL << (TVR_BITS + 4*TVN_BITS)) - 1))
struct tvec {
struct list_head vec[TVN_SIZE];
@@ -356,11 +357,12 @@
vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
} else {
int i;
- /* If the timeout is larger than 0xffffffff on 64-bit
- * architectures then we use the maximum timeout:
+ /* If the timeout is larger than MAX_TVAL (on 64-bit
+ * architectures or with CONFIG_BASE_SMALL=1) then we
+ * use the maximum timeout.
*/
- if (idx > 0xffffffffUL) {
- idx = 0xffffffffUL;
+ if (idx > MAX_TVAL) {
+ idx = MAX_TVAL;
expires = idx + base->timer_jiffies;
}
i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
