Preston_PLB/kernel-aes67
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
4ff4b9e19a
kernel-aes67/kernel
History
Maciej W. Rozycki 4ff4b9e19a ntp: fix calculation of the next jiffie to trigger RTC sync 
We have a bug in the calculation of the next jiffie to trigger the RTC
synchronisation.  The aim here is to run sync_cmos_clock() as close as
possible to the middle of a second.  Which means we want this function to
be called less than or equal to half a jiffie away from when now.tv_nsec
equals 5e8 (500000000).

If this is not the case for a given call to the function, for this purpose
instead of updating the RTC we calculate the offset in nanoseconds to the
next point in time where now.tv_nsec will be equal 5e8.  The calculated
offset is then converted to jiffies as these are the unit used by the
timer.

Hovewer timespec_to_jiffies() used here uses a ceil()-type rounding mode,
where the resulting value is rounded up.  As a result the range of
now.tv_nsec when the timer will trigger is from 5e8 to 5e8 + TICK_NSEC
rather than the desired 5e8 - TICK_NSEC / 2 to 5e8 + TICK_NSEC / 2.

As a result if for example sync_cmos_clock() happens to be called at the
time when now.tv_nsec is between 5e8 + TICK_NSEC / 2 and 5e8 to 5e8 +
TICK_NSEC, it will simply be rescheduled HZ jiffies later, falling in the
same range of now.tv_nsec again.  Similarly for cases offsetted by an
integer multiple of TICK_NSEC.

This change addresses the problem by subtracting TICK_NSEC / 2 from the
nanosecond offset to the next point in time where now.tv_nsec will be
equal 5e8, effectively shifting the following rounding in
timespec_to_jiffies() so that it produces a rounded-to-nearest result.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-06 15:31:48 +02:00
..
irq genirq: switch /proc/irq/*/smp_affinity et al to seqfiles 2008-08-12 16:07:30 -07:00
power ftrace: disable tracing for hibernation 2008-08-28 12:27:39 -07:00
time ntp: fix calculation of the next jiffie to trigger RTC sync 2008-09-06 15:31:48 +02:00
trace Merge branch 'linus' into cpus4096 2008-07-28 23:32:00 +02:00
.gitignore
acct.c bsdacct: fix and add comments around acct_process() 2008-07-25 10:53:47 -07:00
audit_tree.c
audit.c [PATCH] Fix the bug of using AUDIT_STATUS_RATE_LIMIT when set fail, no error output. 2008-08-01 12:15:16 -04:00
audit.h
auditfilter.c Re: [PATCH] the loginuid field should be output in all AUDIT_CONFIG_CHANGE audit messages 2008-08-01 12:15:03 -04:00
auditsc.c [PATCH] audit: Moved variable declaration to beginning of function 2008-09-01 23:06:45 -04:00
backtracetest.c
bounds.c
capability.c security: Fix setting of PF_SUPERPRIV by __capable() 2008-08-14 22:59:43 +10:00
cgroup_debug.c
cgroup.c cgroup: uninline cgroup_has_css_refs() 2008-07-30 09:41:44 -07:00
compat.c
configs.c
cpu.c cpu hotplug: s390 doesn't support additional_cpus anymore. 2008-08-12 16:07:28 -07:00
cpuset.c cpuset: clean up cpuset hierarchy traversal code 2008-07-30 09:41:44 -07:00
delayacct.c per-task-delay-accounting: update taskstats for memory reclaim delay 2008-07-25 10:53:47 -07:00
dma-coherent.c DMA: make dma-coherent.c documentation kdoc-friendly 2008-08-07 06:52:01 -07:00
dma.c
exec_domain.c [PATCH] kill altroot 2008-07-26 20:53:20 -04:00
exit.c pid_ns: (BUG 11391) change ->child_reaper when init->group_leader exits 2008-09-02 19:21:38 -07:00
extable.c
fork.c mmu-notifiers: core 2008-07-28 16:30:21 -07:00
futex_compat.c
futex.c
hrtimer.c Merge branch 'generic-ipi' into generic-ipi-for-linus 2008-07-15 21:55:59 +02:00
itimer.c
kallsyms.c kallsyms: fix potential overflow in binary search 2008-07-25 10:53:27 -07:00
Kconfig.hz sched: fix SCHED_HRTICK dependency 2008-07-28 14:37:38 +02:00
Kconfig.preempt
kexec.c kexec: use a mutex for locking rather than xchg() 2008-08-15 08:35:43 -07:00
kfifo.c
kgdb.c kgdb: fix gdb serial thread queries 2008-08-01 08:39:35 -05:00
kmod.c call_usermodehelper(): increase reliability 2008-07-25 10:53:28 -07:00
kprobes.c kprobes: remove redundant config check 2008-07-25 10:53:30 -07:00
ksysfs.c
kthread.c tracehook: wait_task_inactive 2008-07-26 12:00:09 -07:00
latencytop.c
lockdep_internals.h lockdep: build fix 2008-08-13 12:55:10 +02:00
lockdep_proc.c lockstat: fix numerical output rounding error 2008-08-26 10:37:46 +02:00
lockdep.c lockdep: fix invalid list_del_rcu in zap_class 2008-08-27 08:40:36 +02:00
Makefile Merge branch 'linus' into core/generic-dma-coherent 2008-07-29 00:07:55 +02:00
marker.c markers: fix markers read barrier for multiple probes 2008-07-30 09:41:45 -07:00
module.c [module] Don't let gcc inline load_module() 2008-08-25 11:10:26 -07:00
mutex-debug.c
mutex-debug.h
mutex.c locking: fix mutex @key parameter kernel-doc notation 2008-07-28 18:12:36 +02:00
mutex.h
notifier.c
ns_cgroup.c cgroup_clone: use pid of newly created task for new cgroup 2008-07-25 10:53:37 -07:00
nsproxy.c removed unused #include <linux/version.h>'s 2008-08-23 12:14:12 -07:00
panic.c Add a WARN() macro; this is WARN_ON() + printk arguments 2008-07-25 10:53:29 -07:00
params.c
pid_namespace.c pid_ns: (BUG 11391) change ->child_reaper when init->group_leader exits 2008-09-02 19:21:38 -07:00
pid.c pidns: remove now unused find_pid function. 2008-07-25 10:53:45 -07:00
pm_qos_params.c pm_qos_requirement might sleep 2008-09-02 19:21:40 -07:00
posix-cpu-timers.c
posix-timers.c Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2008-08-11 16:46:11 -07:00
printk.c printk: fix comment for printk ratelimiting 2008-07-30 09:41:45 -07:00
profile.c build kernel/profile.o only when requested 2008-07-25 10:53:27 -07:00
ptrace.c security: Fix setting of PF_SUPERPRIV by __capable() 2008-08-14 22:59:43 +10:00
rcuclassic.c stop_machine: Wean existing callers off stop_machine_run() 2008-07-28 12:16:31 +10:00
rcupdate.c rcu: fix synchronize_rcu() so that kernel-doc works 2008-08-21 09:31:44 +02:00
rcupreempt_trace.c
rcupreempt.c Merge branch 'linus' into cpus4096 2008-07-16 00:29:07 +02:00
rcutorture.c
relay.c relay: fix "full buffer with exactly full last subbuffer" accounting problem 2008-08-05 14:33:46 -07:00
res_counter.c cgroup files: convert res_counter_write() to be a cgroups write_string() handler 2008-07-25 10:53:36 -07:00
resource.c kernel/resource.c: fix new kernel-doc warning 2008-09-02 10:47:30 -07:00
rtmutex_common.h
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c sysdev: Pass the attribute to the low level sysdev show/store function 2008-07-21 21:55:02 -07:00
rtmutex.c
rtmutex.h
rwsem.c
sched_clock.c sched_clock: fix cpu_clock() 2008-08-25 17:39:57 +02:00
sched_cpupri.c
sched_cpupri.h
sched_debug.c
sched_fair.c sched: fix mysql+oltp regression 2008-08-11 14:49:29 +02:00
sched_features.h sched: enable LB_BIAS by default 2008-08-21 08:18:02 +02:00
sched_idletask.c
sched_rt.c sched: rt-bandwidth accounting fix 2008-08-28 13:42:38 +02:00
sched_stats.h
sched.c Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2008-08-16 17:15:32 -07:00
seccomp.c
semaphore.c semaphore: __down_common: use signal_pending_state() 2008-08-05 14:33:47 -07:00
signal.c tracehook: fix SA_NOCLDWAIT 2008-08-19 20:37:07 -07:00
smp.c smp: have smp_call_function_single() detect invalid CPUs 2008-08-25 17:45:48 -07:00
softirq.c Full conversion to early_initcall() interface, remove old interface 2008-07-26 12:00:04 -07:00
softlockup.c softlockup: minor cleanup, don't check task->state twice 2008-09-02 10:49:51 -07:00
spinlock.c lockdep: spin_lock_nest_lock(), checkpatch fixes 2008-08-13 13:56:51 +02:00
srcu.c
stacktrace.c
stop_machine.c stop_machine: remove unused variable 2008-08-12 17:52:55 +10:00
sys_ni.c signalfd: fix undefined reference to `compat_sys_signalfd4' when !CONFIG_SIGNALFD 2008-07-25 11:35:41 -07:00
sys.c fix setpriority(PRIO_PGRP) thread iterator breakage 2008-08-20 15:40:32 -07:00
sysctl_check.c sysctl: check for bogus modes 2008-07-25 10:53:45 -07:00
sysctl.c lost sysctl fix 2008-07-27 09:45:34 -07:00
taskstats.c taskstats: remove initialization of static per-cpu variable 2008-07-25 10:53:47 -07:00
test_kprobes.c
time.c
timeconst.pl
timer.c Merge branch 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm 2008-07-14 16:06:58 -07:00
tsacct.c task IO accounting: move all IO statistics in struct task_io_accounting 2008-07-27 16:12:28 -07:00
uid16.c
user_namespace.c removed unused #include <linux/version.h>'s 2008-08-23 12:14:12 -07:00
user.c
utsname_sysctl.c removed unused #include <linux/version.h>'s 2008-08-23 12:14:12 -07:00
utsname.c removed unused #include <linux/version.h>'s 2008-08-23 12:14:12 -07:00
wait.c
workqueue.c Merge branch 'core/locking' into core/urgent 2008-08-12 00:11:49 +02:00