David Fries 6ffc787a44 system timer: fix crash in <100Hz system timer ... The kernel has a divide by zero crash when trying to run the system timer less than 100Hz. The problem is x/(HZ/USER_HZ) and related. Now x*(USER_HZ/HZ) will be used if HZ<USER_HZ. I'm running the Linux kernel under qemu and went to run a slower system timer to take less CPU (and battery) on the host. I found that the kernel paniced under emulation because of a divide by zero in three places. Here is the patch. The base git was updated today 01-05-2008. I went for a 20Hz system time by adding config HZ_20 etc to kernel/Kconfig.hz. With this patch I verified the system timer by looking at /proc/interrupts. [akpm@linux-foundation.org: partially clean up the macro maze] Signed-off-by: David Fries <david@fries.net> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2008-02-06 10:41:10 -08:00
..
irq	genirq: stackdump after the "Trying to free already-free IRQ" message	2008-01-30 13:33:24 +01:00
power	kernel/power/disk.c: make code static	2008-02-05 09:44:22 -08:00
time	time: fix sysfs_show_{available,current}_clocksources() buffer overflow problem	2008-02-06 10:41:03 -08:00
.gitignore
acct.c	acct: real_parent ppid	2008-01-07 14:55:37 -08:00
audit.c	[AUDIT] ratelimit printk messages audit	2008-02-01 14:25:04 -05:00
audit.h	[PATCH] audit: watching subtrees	2007-10-21 02:37:45 -04:00
audit_tree.c	[PATCH] audit: watching subtrees	2007-10-21 02:37:45 -04:00
auditfilter.c	[AUDIT] make audit=0 really stop audit messages	2008-02-01 14:24:33 -05:00
auditsc.c	[AUDIT] create context if auditing was ever enabled	2008-02-01 14:24:45 -05:00
backtracetest.c	x86: add a simple backtrace test module	2008-01-30 13:33:08 +01:00
capability.c	Add 64-bit capability support to the kernel	2008-02-05 09:44:20 -08:00
cgroup.c	Improve cgroup printks	2007-11-14 18:45:37 -08:00
cgroup_debug.c	Task Control Groups: simple task cgroup debug info subsystem	2007-10-19 11:53:36 -07:00
compat.c	Merge ssh://master.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-hrt	2007-10-18 15:12:41 -07:00
configs.c	use simple_read_from_buffer in kernel/	2007-05-09 12:30:49 -07:00
cpu.c	cpu-hotplug: replace per-subsystem mutexes with get_online_cpus()	2008-01-25 21:08:02 +01:00
cpuset.c	cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()	2008-01-25 21:08:02 +01:00
delayacct.c	Add scaled time to taskstats based process accounting	2007-10-18 14:37:28 -07:00
dma.c	whitespace fixes: DMA channel allocator	2007-10-18 14:37:24 -07:00
exec_domain.c	whitespace fixes: execution domains	2007-10-18 14:37:26 -07:00
exit.c	do_wait: remove one "else if" branch	2008-02-06 10:41:04 -08:00
extable.c	module: Don't report discarded init pages as kernel text.	2008-01-29 17:13:18 +11:00
fork.c	idle_regs() must be __cpuinit	2008-02-06 10:41:08 -08:00
futex.c	futex: Add bitset conditional wait/wakeup functionality	2008-02-01 17:45:14 +01:00
futex_compat.c	futex: Add bitset conditional wait/wakeup functionality	2008-02-01 17:45:14 +01:00
hrtimer.c	timerfd: new timerfd API	2008-02-05 09:44:07 -08:00
itimer.c	whitespace fixes: interval timers	2007-10-18 14:37:26 -07:00
kallsyms.c	remove support for un-needed _extratext section	2008-02-06 10:41:01 -08:00
Kconfig.hz	sched: high-res preemption tick	2008-01-25 21:08:29 +01:00
Kconfig.preempt	sched: remove the !PREEMPT_BKL code	2008-01-25 21:08:33 +01:00
kexec.c	vmcoreinfo: add the array length of "free_list" for filtering free pages	2008-01-08 16:10:36 -08:00
kfifo.c	is_power_of_2: kernel/kfifo.c	2007-07-16 09:05:50 -07:00
kmod.c	Fix unbalanced helper_lock in kernel/kmod.c	2008-01-17 15:38:59 -08:00
kprobes.c	x86: kprobes: add kprobes smoke tests that run on boot	2008-01-30 13:32:53 +01:00
ksysfs.c	Kobject: convert remaining kobject_unregister() to kobject_put()	2008-01-24 20:40:40 -08:00
kthread.c	sched: fix, always create kernel threads with normal priority	2008-01-25 21:08:33 +01:00
latencytop.c	sched: latencytop support	2008-01-25 21:08:34 +01:00
lockdep.c	softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks	2008-01-25 21:08:02 +01:00
lockdep_internals.h
lockdep_proc.c	lockdep: Avoid /proc/lockdep & lock_stat infinite output	2007-10-11 22:11:11 +02:00
Makefile	latency.c: use QoS infrastructure	2008-02-05 09:44:22 -08:00
marker.c	Linux Kernel Markers: fix marker mutex not taken upon module load	2007-11-14 18:45:40 -08:00
module.c	x86/non-x86: percpu, node ids, apic ids x86.git fixup	2008-01-30 13:33:32 +01:00
mutex-debug.c
mutex-debug.h
mutex.c	Add mutex_lock_killable	2007-12-06 17:37:59 -05:00
mutex.h
notifier.c	kernel/notifier.c should #include <linux/reboot.h>	2008-02-06 10:41:02 -08:00
ns_cgroup.c	cgroups: implement namespace tracking subsystem	2007-10-19 11:53:37 -07:00
nsproxy.c	pid namespaces: allow cloning of new namespace	2007-10-19 11:53:39 -07:00
panic.c	debug: add the end-of-trace marker and the module list to	2008-01-30 13:32:50 +01:00
params.c	kernel/params.c: remove sparse-warning (different signedness)	2008-02-06 10:41:08 -08:00
pid.c	pidns: Place under CONFIG_EXPERIMENTAL	2007-11-14 18:45:43 -08:00
pm_qos_params.c	pm qos infrastructure and interface	2008-02-05 09:44:22 -08:00
posix-cpu-timers.c	sched: rt-watchdog: fix .rlim_max = RLIM_INFINITY	2008-01-25 21:08:32 +01:00
posix-timers.c	timerfd: new timerfd API	2008-02-05 09:44:07 -08:00
printk.c	printk.c: use unsigned ints instead of longs for logbuf index	2008-02-06 10:41:04 -08:00
profile.c	debug: clean up kernel/profile.c	2008-01-25 21:08:33 +01:00
ptrace.c	kernel/ptrace.c should #include <linux/syscalls.h>	2008-02-06 10:41:02 -08:00
rcuclassic.c	Preempt-RCU: implementation	2008-01-25 21:08:24 +01:00
rcupdate.c	Preempt-RCU: fix rcu_barrier for preemptive environment.	2008-01-25 21:08:24 +01:00
rcupreempt.c	Preempt-RCU: CPU Hotplug handling	2008-01-25 21:08:25 +01:00
rcupreempt_trace.c	Preempt-RCU: implementation	2008-01-25 21:08:24 +01:00
rcutorture.c	cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()	2008-01-25 21:08:02 +01:00
relay.c	relay: nopage	2008-02-06 10:41:07 -08:00
resource.c	Add IORESOUCE_BUSY flag for System RAM	2007-11-14 18:45:39 -08:00
rtmutex-debug.c	Use helpers to obtain task pid in printks	2007-10-19 11:53:43 -07:00
rtmutex-debug.h
rtmutex-tester.c	Driver core: change sysdev classes to use dynamic kobject names	2008-01-24 20:40:40 -08:00
rtmutex.c	Use helpers to obtain task pid in printks	2007-10-19 11:53:43 -07:00
rtmutex.h
rtmutex_common.h	FUTEX: Tidy up the code	2007-07-16 09:05:49 -07:00
rwsem.c	sched: mark rwsem functions as __sched for wchan/profiling	2007-12-18 15:21:13 +01:00
sched.c	Merge branch 'task_killable' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc	2008-02-01 11:45:47 +11:00
sched_debug.c	sched: keep total / count stats in addition to the max for	2008-01-25 21:08:35 +01:00
sched_fair.c	sched: let +nice tasks have smaller impact	2008-01-31 22:45:22 +01:00
sched_idletask.c	sched: high-res preemption tick	2008-01-25 21:08:29 +01:00
sched_rt.c	sched: fix goto retry in pick_next_task_rt()	2008-01-25 21:08:34 +01:00
sched_stats.h	sched: clean up kernel/sched_stat.h	2007-11-28 15:52:56 +01:00
seccomp.c	make seccomp zerocost in schedule	2007-07-16 09:05:50 -07:00
signal.c	Add arch_ptrace_stop	2008-02-06 10:41:07 -08:00
softirq.c	time: track accurate idle time with tick_sched.idle_sleeptime	2008-01-30 13:30:04 +01:00
softlockup.c	debug: softlockup looping fix	2008-02-02 14:27:45 +11:00
spinlock.c	spinlock: lockbreak cleanup	2008-01-30 13:31:20 +01:00
srcu.c	make srcu_readers_active() static	2008-02-06 10:41:02 -08:00
stacktrace.c
stop_machine.c	stopmachine: semaphore to mutex	2008-02-06 10:41:08 -08:00
sys.c	kernel/sys.c: get rid of expensive divides in groups_sort()	2008-02-06 10:41:09 -08:00
sys_ni.c	timerfd: new timerfd API	2008-02-05 09:44:07 -08:00
sysctl.c	get rid of NR_OPEN and introduce a sysctl_nr_open	2008-02-06 10:41:06 -08:00
sysctl_check.c	capabilities: introduce per-process capability bounding set	2008-02-05 09:44:20 -08:00
taskstats.c	kernel/taskstats.c: fix bogus nlmsg_free()	2007-11-14 18:45:44 -08:00
test_kprobes.c	x86: kprobes: add kprobes smoke tests that run on boot	2008-01-30 13:32:53 +01:00
time.c	system timer: fix crash in <100Hz system timer	2008-02-06 10:41:10 -08:00
timer.c	taskstats scaled time cleanup	2008-02-06 10:41:00 -08:00
tsacct.c	Add scaled time to taskstats based process accounting	2007-10-18 14:37:28 -07:00
uid16.c	header cleaning: don't include smp_lock.h when not used	2007-05-08 11:15:07 -07:00
user.c	uids: merge multiple error paths in alloc_uid() into one	2008-01-25 21:08:26 +01:00
user_namespace.c	Fix user namespace exiting OOPs	2007-09-19 11:24:18 -07:00
utsname.c	Fix UTS corruption during clone(CLONE_NEWUTS)	2007-09-19 11:24:17 -07:00
utsname_sysctl.c	Isolate the UTS namespace's domainname and hostname back	2007-11-29 09:24:53 -08:00
wait.c	wait: Use TASK_NORMAL	2007-12-06 17:34:36 -05:00
workqueue.c	cpu-hotplug: replace per-subsystem mutexes with get_online_cpus()	2008-01-25 21:08:02 +01:00