The clock_was_set() call in seconds_overflow() which happens only when
leap seconds are inserted / deleted is wrong in two aspects:
1. it results in a call to on_each_cpu() with interrupts disabled
2. it is potential deadlock source vs. call_lock in smp_call_function()
The only possible side effect of the removal might be, that an absolute
CLOCK_REALTIME timer fires 1 second too late, in the rare case of leap
second deletion and an absolute CLOCK_REALTIME timer which expires in
the affected time frame. It will never fire too early.
This was probably observed by the reporter of a June 30th -> July 1st
hang: http://lkml.org/lkml/2007/7/3/
A similar problem was observed by Dave Jones, who provided a screen shot
with a lockdep back trace, which allowed to analyse the problem.
Signed-off-by: Thomas Gleixner <[email protected]>
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -122,7 +122,6 @@ void second_overflow(void)
*/
time_interpolator_update(-NSEC_PER_SEC);
time_state = TIME_OOP;
- clock_was_set();
printk(KERN_NOTICE "Clock: inserting leap second "
"23:59:60 UTC\n");
}
@@ -137,7 +136,6 @@ void second_overflow(void)
*/
time_interpolator_update(NSEC_PER_SEC);
time_state = TIME_WAIT;
- clock_was_set();
printk(KERN_NOTICE "Clock: deleting leap second "
"23:59:59 UTC\n");
}
-
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