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, 1 deletions

diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index bdfb8dd1050c..1a4a7dd78777 100644
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -228,6 +228,7 @@ print_tickdevice(struct seq_file *m, struct tick_device *td, int cpu)
         SEQ_printf(m, " event_handler:  ");
         print_name_offset(m, dev->event_handler);
         SEQ_printf(m, "\n");
+        SEQ_printf(m, " retries:        %lu\n", dev->retries);
 }
 
 static void timer_list_show_tickdevices(struct seq_file *m)
@@ -257,7 +258,7 @@ static int timer_list_show(struct seq_file *m, void *v)
         u64 now = ktime_to_ns(ktime_get());
         int cpu;
 
-        SEQ_printf(m, "Timer List Version: v0.5\n");
+        SEQ_printf(m, "Timer List Version: v0.6\n");
         SEQ_printf(m, "HRTIMER_MAX_CLOCK_BASES: %d\n", HRTIMER_MAX_CLOCK_BASES);
         SEQ_printf(m, "now at %Ld nsecs\n", (unsigned long long)now);