Steven Rostedt 4143c5cb36 ring-buffer: prevent infinite looping on time stamping ... Impact: removal of unnecessary looping The lockless part of the ring buffer allows for reentry into the code from interrupts. A timestamp is taken, a test is preformed and if it detects that an interrupt occurred that did tracing, it tries again. The problem arises if the timestamp code itself causes a trace. The detection will detect this and loop again. The difference between this and an interrupt doing tracing, is that this will fail every time, and cause an infinite loop. Currently, we test if the loop happens 1000 times, and if so, it will produce a warning and disable the ring buffer. The problem with this approach is that it makes it difficult to perform some types of tracing (tracing the timestamp code itself). Each trace entry has a delta timestamp from the previous entry. If a trace entry is reserved but and interrupt occurs and traces before the previous entry is commited, the delta timestamp for that entry will be zero. This actually makes sense in terms of tracing, because the interrupt entry happened before the preempted entry was commited, so one may consider the two happening at the same time. The order is still preserved in the buffer. With this idea, instead of trying to get a new timestamp if an interrupt made it in between the timestamp and the test, the entry could simply make the delta zero and continue. This will prevent interrupts or tracers in the timer code from causing the above loop. Signed-off-by: Steven Rostedt <srostedt@redhat.com>		2008-11-10 21:47:37 -05:00
..
irq	irq: make variable static	2008-10-22 07:37:17 +02:00
power	PM_TEST_SUSPEND should depend on RTC_CLASS, not RTC_LIB	2008-11-01 12:40:38 -07:00
time	Merge branch 'timers/range-hrtimers' into v28-range-hrtimers-for-linus-v2	2008-10-22 09:48:06 +02:00
trace	ring-buffer: prevent infinite looping on time stamping	2008-11-10 21:47:37 -05:00
.gitignore	Update kernel/.gitignore with new auto-generated files	2008-02-09 23:27:01 -08:00
acct.c	tty: Fix abusers of current->sighand->tty	2008-10-13 09:51:42 -07:00
audit_tree.c	[PATCH] get rid of nameidata in audit_tree	2008-10-23 05:12:53 -04:00
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	[PATCH 1/2] audit: move extern declarations to audit.h	2008-04-28 06:28:04 -04:00
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	tty: Fix abusers of current->sighand->tty	2008-10-13 09:51:42 -07:00
backtracetest.c	backtrace: replace timer with tasklet + completions	2008-06-27 18:09:16 +02:00
bounds.c	Add kbuild.h that contains common definitions for kbuild users	2008-04-29 08:06:29 -07:00
capability.c	security: Fix setting of PF_SUPERPRIV by __capable()	2008-08-14 22:59:43 +10:00
cgroup_debug.c	cgroups: fix probable race with put_css_set[_taskexit] and find_css_set	2008-10-20 08:52:38 -07:00
cgroup_freezer.c	freezer_cg: simplify freezer_change_state()	2008-10-30 11:38:45 -07:00
cgroup.c	cgroups: fix invalid cgrp->dentry before cgroup has been completely removed	2008-11-06 15:41:19 -08:00
compat.c	Merge branches 'timers/clocksource', 'timers/hrtimers', 'timers/nohz', 'timers/ntp', 'timers/posixtimers' and 'timers/debug' into v28-timers-for-linus	2008-10-20 13:14:06 +02:00
configs.c	kernel/configs.c: remove useless comments	2008-10-20 08:52:34 -07:00
cpu.c	cpumask: introduce new API, without changing anything	2008-11-06 09:05:33 +01:00
cpuset.c	cpuset: use seq_*mask_* to print masks	2008-10-20 08:52:39 -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-coherent: export dma_[alloc|release]_from_coherent methods	2008-08-22 08:34:53 +02:00
dma.c	kernel/dma.c: remove a CVS keyword	2008-10-16 11:21:30 -07:00
exec_domain.c	proc: move /proc/execdomains to kernel/exec_domain.c	2008-10-23 14:30:41 +04:00
exit.c	Merge branch 'tracing-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2008-10-20 13:35:07 -07:00
extable.c	module: Don't report discarded init pages as kernel text.	2008-01-29 17:13:18 +11:00
fork.c	Merge branch 'timers/range-hrtimers' into v28-range-hrtimers-for-linus-v2	2008-10-22 09:48:06 +02:00
freezer.c	freezer_cg: use thaw_process() in unfreeze_cgroup()	2008-10-30 11:38:45 -07:00
futex_compat.c	futex_compat __user annotation	2008-03-30 14:18:41 -07:00
futex.c	hrtimer: make the futex() system call use the per process slack value	2008-09-11 07:17:00 -07:00
hrtimer.c	Merge branch 'timers/range-hrtimers' into v28-range-hrtimers-for-linus-v2	2008-10-22 09:48:06 +02:00
itimer.c	timers: fix itimer/many thread hang	2008-09-14 16:25:35 +02:00
kallsyms.c	kernel/kallsyms.c: fix double return	2008-10-16 11:21:32 -07:00
Kconfig.freezer	container freezer: implement freezer cgroup subsystem	2008-10-20 08:52:34 -07:00
Kconfig.hz	sched: fix SCHED_HRTICK dependency	2008-07-28 14:37:38 +02:00
Kconfig.preempt	rcu: move PREEMPT_RCU config option back under PREEMPT	2008-03-10 18:01:20 -07:00
kexec.c	kexec: fix crash_save_vmcoreinfo_init build problem	2008-10-20 15:28:50 -07:00
kfifo.c
kgdb.c	kgdb: call touch_softlockup_watchdog on resume	2008-10-06 13:50:59 -05:00
kmod.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus	2008-10-16 12:38:34 -07:00
kprobes.c	make kprobes.c:kretprobe_table_lock() static	2008-10-16 11:21:52 -07:00
ksysfs.c	profiling: dynamically enable readprofile at runtime	2008-10-16 11:21:31 -07:00
kthread.c	Merge branch 'tracing-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2008-10-20 13:35:07 -07:00
latencytop.c	kernel: use non-racy method for proc entries creation	2008-04-29 08:06:22 -07:00
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 irqs on/off ip tracing	2008-10-28 11:19:07 +01:00
Makefile	Merge branch 'tracing/ftrace' into tracing/urgent	2008-10-22 09:08:14 +02:00
marker.c	markers: bit-field is not thread-safe nor smp-safe	2008-10-14 10:38:45 +02:00
module.c	Merge branch 'proc' of git://git.kernel.org/pub/scm/linux/kernel/git/adobriyan/proc	2008-10-23 12:04:37 -07:00
mutex-debug.c	mutex-debug: check mutex magic before owner	2008-05-16 16:53:35 +02:00
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	ftrace: ignore functions that cannot be kprobe-ed	2008-10-14 10:34:22 +02:00
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	Make panic= and panic_on_oops into core_params	2008-10-22 10:00:25 +11:00
params.c	Fix compile warning in kernel/params.c	2008-10-23 12:09:00 -07:00
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	timers: fix itimer/many thread hang, v2	2008-09-23 13:38:44 +02:00
posix-timers.c	Merge branch 'timers/range-hrtimers' into v28-range-hrtimers-for-linus-v2	2008-10-22 09:48:06 +02:00
printk.c	printk: remove unused code from kernel/printk.c	2008-10-23 21:54:29 +02:00
profile.c	kernel/profile: fix profile_init() section mismatch	2008-10-30 11:38:46 -07:00
ptrace.c	make ptrace_untrace() static	2008-10-20 08:52:39 -07:00
rcuclassic.c	rcu: RCU-based detection of stalled CPUs for Classic RCU, fix	2008-10-03 10:41:00 +02:00
rcupdate.c	rcupdate: fix bug of rcu_barrier*()	2008-10-21 15:59:53 +02:00
rcupreempt_trace.c	rcu: trace fix possible mem-leak	2008-08-15 17:54:40 +02:00
rcupreempt.c	byteorder: remove direct includes of linux/byteorder/swab[b].h	2008-10-20 08:52:40 -07:00
rcutorture.c	byteorder: remove direct includes of linux/byteorder/swab[b].h	2008-10-20 12:51:53 -07:00
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	reserve_region_with_split: Fix GFP_KERNEL usage under spinlock	2008-11-01 09:53:58 -07:00
rtmutex_common.h	Don't operate with pid_t in rtmutex tester	2008-02-08 09:22:41 -08:00
rtmutex-debug.c	Don't operate with pid_t in rtmutex tester	2008-02-08 09:22:41 -08:00
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	hrtimer: convert kernel/* to the new hrtimer apis	2008-09-05 21:35:13 -07:00
rtmutex.h
rwsem.c	sched: mark rwsem functions as __sched for wchan/profiling	2007-12-18 15:21:13 +01:00
sched_clock.c	sched_clock: prevent scd->clock from moving backwards	2008-10-10 11:17:04 +02:00
sched_cpupri.c	sched: use a 2-d bitmap for searching lowest-pri CPU	2008-06-06 15:19:28 +02:00
sched_cpupri.h	sched: fix the cpuprio count really	2008-06-06 15:19:44 +02:00
sched_debug.c	sched: change sched_debug's mode to 0444	2008-10-30 11:37:57 +01:00
sched_fair.c	sched: fix buddies for group scheduling	2008-11-05 10:30:15 +01:00
sched_features.h	sched: backward looking buddy	2008-11-05 10:30:14 +01:00
sched_idletask.c	sched: add CONFIG_SMP consistency	2008-10-22 10:01:52 +02:00
sched_rt.c	Merge commit 'v2.6.28-rc1' into sched/urgent	2008-10-24 12:48:46 +02:00
sched_stats.h	Merge branch 'proc' of git://git.kernel.org/pub/scm/linux/kernel/git/adobriyan/proc	2008-10-23 12:04:37 -07:00
sched.c	sched: fix memory leak in a failure path	2008-11-07 08:29:58 +01:00
seccomp.c
semaphore.c	semaphore: __down_common: use signal_pending_state()	2008-08-05 14:33:47 -07:00
signal.c	'kill sig -1' must only apply to caller's namespace	2008-10-30 11:38:46 -07:00
smp.c	generic-ipi: fix the smp_mb() placement	2008-11-06 08:41:56 +01:00
softirq.c	Merge branches 'timers/clocksource', 'timers/hrtimers', 'timers/nohz', 'timers/ntp', 'timers/posixtimers' and 'timers/debug' into v28-timers-for-linus	2008-10-20 13:14:06 +02:00
softlockup.c	Make the taint flags reliable	2008-10-16 11:21:31 -07:00
spinlock.c	lockdep: spin_lock_nest_lock(), checkpatch fixes	2008-08-13 13:56:51 +02:00
srcu.c	make srcu_readers_active() static	2008-02-06 10:41:02 -08:00
stacktrace.c	stacktrace: fix modular build, export print_stack_trace and save_stack_trace	2008-06-30 09:20:55 +02:00
stop_machine.c	Revert "Call init_workqueues before pre smp initcalls."	2008-10-25 19:53:38 -07:00
sys_ni.c	Configure out AIO support	2008-10-16 11:21:51 -07:00
sys.c	Merge branch 'timers/range-hrtimers' into v28-range-hrtimers-for-linus-v2	2008-10-22 09:48:06 +02:00
sysctl_check.c	sysctl: check for bogus modes	2008-07-25 10:53:45 -07:00
sysctl.c	Merge commit 'v2.6.28-rc2' into tracing/urgent	2008-10-27 10:50:54 +01:00
taskstats.c	taskstats: remove initialization of static per-cpu variable	2008-07-25 10:53:47 -07:00
test_kprobes.c	kprobes: kretprobe user entry-handler	2008-02-06 10:41:11 -08:00
time.c	select: add a timespec_add_safe() function	2008-09-05 21:34:57 -07:00
timeconst.pl	Make constants in kernel/timeconst.h fixed 64 bits	2008-05-02 16:18:42 -07:00
timer.c	Add round_jiffies_up and related routines	2008-11-06 08:42:48 +01:00
tracepoint.c	tracepoint: check if the probe has been registered	2008-10-27 16:45:46 +01:00
tsacct.c	task IO accounting: move all IO statistics in struct task_io_accounting	2008-07-27 16:12:28 -07:00
uid16.c	asmlinkage_protect replaces prevent_tail_call	2008-04-10 17:28:26 -07:00
user_namespace.c	removed unused #include <linux/version.h>'s	2008-08-23 12:14:12 -07:00
user.c	sched: rt-bandwidth for user grouping interface	2008-08-19 13:10:09 +02:00
utsname_sysctl.c	sysctl: simplify ->strategy	2008-10-16 11:21:47 -07:00
utsname.c	removed unused #include <linux/version.h>'s	2008-08-23 12:14:12 -07:00
wait.c	wait: kill is_sync_wait()	2008-10-16 11:21:31 -07:00
workqueue.c	cpumask: introduce new API, without changing anything	2008-11-06 09:05:33 +01:00