linux/kernel/time
Thomas Gleixner 746976a301 NTP: remove clock_was_set() call to prevent deadlock
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/2007/7/3/103

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 <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-03 13:54:27 -07:00
..
clockevents.c [PATCH] clockevents: remove bad designed sysfs support for now 2007-03-26 14:07:23 -07:00
clocksource.c clocksource: fix lock order in the resume path 2007-05-15 08:54:00 -07:00
jiffies.c [PATCH] fix jiffies clocksource inittime 2007-04-04 21:12:47 -07:00
Kconfig [PATCH] hrtimers: add high resolution timer support 2007-02-16 08:13:59 -08:00
Makefile Move timekeeping code to timekeeping.c 2007-05-08 11:15:06 -07:00
ntp.c NTP: remove clock_was_set() call to prevent deadlock 2007-07-03 13:54:27 -07:00
tick-broadcast.c Ignore bogus ACPI info for offline CPUs 2007-05-23 20:14:11 -07:00
tick-common.c highres/dyntick: prevent xtime lock contention 2007-05-08 11:15:10 -07:00
tick-internal.h highres/dyntick: prevent xtime lock contention 2007-05-08 11:15:10 -07:00
tick-oneshot.c [PATCH] clockevents: Fix suspend/resume to disk hangs 2007-03-16 19:35:25 -07:00
tick-sched.c NOHZ: prevent multiplication overflow - stop timer for huge timeouts 2007-05-29 18:11:10 -07:00
timekeeping.c timekeeping fix patch got mis-applied 2007-05-14 12:13:11 -07:00
timer_list.c Fix printk format warnings in timer_list.c 2007-05-09 12:30:50 -07:00
timer_stats.c timer stats: speedups 2007-06-01 08:18:30 -07:00