clockevents: Sanitize min_delta_ns adjustment and prevent overflows

The current logic which handles clock events programming failures can
increase min_delta_ns unlimited and even can cause overflows.

Sanitize it by:
 - prevent zero increase when min_delta_ns == 1
 - limiting min_delta_ns to a jiffie
 - bail out if the jiffie limit is hit
 - add retries stats for /proc/timer_list so we can gather data

Reported-by: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index 0cf725bdd2a1..fc53492b6ad7 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -73,6 +73,7 @@ enum clock_event_nofitiers {
  * @list:               list head for the management code
  * @mode:               operating mode assigned by the management code
  * @next_event:         local storage for the next event in oneshot mode
+ * @retries:            number of forced programming retries
  */
 struct clock_event_device {
         const char              *name;
@@ -93,6 +94,7 @@ struct clock_event_device {
         struct list_head        list;
         enum clock_event_mode   mode;
         ktime_t                 next_event;
+        unsigned long           retries;
 };
 
 /*