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authorHildner, Christian <christian.hildner@siemens.com>2012-10-08 17:49:03 +0400
committerThomas Gleixner <tglx@linutronix.de>2012-10-09 23:27:14 +0400
commit26cff4e2aa4d666dc6a120ea34336b5057e3e187 (patch)
treebe3f9c189519e4e42bb825d15adefb4d238a7214 /kernel
parentdb8c246937713e60b7628661ccc187eeb81f2bae (diff)
downloadlinux-26cff4e2aa4d666dc6a120ea34336b5057e3e187.tar.xz
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). 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
Diffstat (limited to 'kernel')
-rw-r--r--kernel/timer.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/kernel/timer.c b/kernel/timer.c
index d5de1b2292aa..367d00858482 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -63,6 +63,7 @@ EXPORT_SYMBOL(jiffies_64);
#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];
@@ -359,11 +360,12 @@ __internal_add_timer(struct tvec_base *base, struct timer_list *timer)
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;