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Frederic Weisbecker c85a17e226 tracing/urgent: fix unbalanced ftrace_start_up 
Perfcounter reports the following stats for a wide system
profiling:

 #
 # (2364 samples)
 #
 # Overhead  Symbol
 # ........  ......
 #
    15.40%  [k] mwait_idle_with_hints
     8.29%  [k] read_hpet
     5.75%  [k] ftrace_caller
     3.60%  [k] ftrace_call
     [...]

This snapshot has been taken while neither the function tracer nor
the function graph tracer was running.
With dynamic ftrace, such results show a wrong ftrace behaviour
because all calls to ftrace_caller or ftrace_graph_caller (the patched
calls to mcount) are supposed to be patched into nop if none of those
tracers are running.

The problem occurs after the first run of the function tracer. Once we
launch it a second time, the callsites will never be nopped back,
unless you set custom filters.
For example it happens during the self tests at boot time.
The function tracer selftest runs, and then the dynamic tracing is
tested too. After that, the callsites are left un-nopped.

This is because the reset callback of the function tracer tries to
unregister two ftrace callbacks in once: the common function tracer
and the function tracer with stack backtrace, regardless of which
one is currently in use.
It then creates an unbalance on ftrace_start_up value which is expected
to be zero when the last ftrace callback is unregistered. When it
reaches zero, the FTRACE_DISABLE_CALLS is set on the next ftrace
command, triggering the patching into nop. But since it becomes
unbalanced, ie becomes lower than zero, if the kernel functions
are patched again (as in every further function tracer runs), they
won't ever be nopped back.

Note that ftrace_call and ftrace_graph_call are still patched back
to ftrace_stub in the off case, but not the callers of ftrace_call
and ftrace_graph_caller. It means that the tracing is well deactivated
but we waste a useless call into every kernel function.

This patch just unregisters the right ftrace_ops for the function
tracer on its reset callback and ignores the other one which is
not registered, fixing the unbalance. The problem also happens
is .30

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: stable@kernel.org
 		2009-06-20 06:28:46 +02:00
..
irq irq: slab alloc for default irq_affinity 2009-06-12 13:50:23 +03:00
power Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-06-14 13:46:25 -07:00
time Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 2009-06-11 09:01:14 +03:00
trace tracing/urgent: fix unbalanced ftrace_start_up 2009-06-20 06:28:46 +02:00
.gitignore
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Kconfig.freezer container freezer: implement freezer cgroup subsystem 2008-10-20 08:52:34 -07:00
Kconfig.hz
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Kconfig.preempt rcu: provide RCU options on non-preempt architectures too 2008-12-25 09:31:28 +01:00
Makefile Merge branch 'linus' into perfcounters/core 2009-06-11 17:55:42 +02:00
acct.c [CVE-2009-0029] System call wrappers part 04 2009-01-14 14:15:19 +01:00
async.c async: Fix lack of boot-time console due to insufficient synchronization 2009-06-08 12:31:53 -07:00
audit.c Audit: remove spaces from audit_log_d_path 2009-04-05 13:49:04 -04:00
audit.h fixing audit rule ordering mess, part 1 2009-01-04 15:14:41 -05:00
audit_tree.c Switch collect_mounts() to struct path 2009-06-11 21:36:01 -04:00
auditfilter.c inotify: use GFP_NOFS in kernel_event() to work around a lockdep false-positive 2009-05-06 16:36:09 -07:00
auditsc.c Audit: remove spaces from audit_log_d_path 2009-04-05 13:49:04 -04:00
backtracetest.c
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bounds.c
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capability.c [CVE-2009-0029] System call wrappers part 04 2009-01-14 14:15:19 +01:00
cgroup.c Push BKL down into ->remount_fs() 2009-06-11 21:36:11 -04:00
cgroup_debug.c debug cgroup: remove unneeded cgroup_lock 2009-04-02 19:04:54 -07:00
cgroup_freezer.c freezer_cg: disable writing freezer.state of root cgroup 2008-11-12 17:17:16 -08:00
compat.c signals: implement sys_rt_tgsigqueueinfo 2009-04-30 19:24:24 +02:00
configs.c kernel/configs.c: remove useless comments 2008-10-20 08:52:34 -07:00
cpu.c cpumask: use set_cpu_active in init/main.c 2009-03-30 22:05:12 +10:30
cpuset.c x86: remove some alloc_bootmem_cpumask_var calling 2009-06-11 19:27:07 +03:00
cred-internals.h CRED: Inaugurate COW credentials 2008-11-14 10:39:23 +11:00
cred.c CRED: Rename cred_exec_mutex to reflect that it's a guard against ptrace 2009-05-11 08:15:36 +10:00
delayacct.c schedstat: consolidate per-task cpu runtime stats 2008-12-18 13:54:01 +01:00
dma-coherent.c dma-coherent: Restore dma_alloc_from_coherent() large alloc fall back policy. 2009-01-21 18:51:53 +09:00
dma.c kernel/dma.c: remove a CVS keyword 2008-10-16 11:21:30 -07:00
exec_domain.c Get rid of indirect include of fs_struct.h 2009-03-31 23:00:27 -04:00
exit.c Merge branch 'perfcounters-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-06-11 14:01:07 -07:00
extable.c Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-04-05 11:04:19 -07:00
fork.c Merge branch 'linus' into perfcounters/core 2009-06-11 17:55:42 +02:00
freezer.c freezer_cg: use thaw_process() in unfreeze_cgroup() 2008-10-30 11:38:45 -07:00
futex.c futex: fix restart in wait_requeue_pi 2009-05-20 10:34:32 +02:00
futex_compat.c CRED: Use RCU to access another task's creds and to release a task's own creds 2008-11-14 10:39:19 +11:00
hrtimer.c hrtimer: fix rq->lock inversion (again) 2009-03-31 14:52:52 +02:00
hung_task.c softlockup: ensure the task has been switched out once 2009-02-11 11:04:16 +01:00
itimer.c timers: split process wide cpu clocks/timers 2009-02-05 13:04:33 +01:00
kallsyms.c kernel/kallsyms.c: replace deprecated __initcall with device_initcall and fix whitespace 2009-06-09 22:37:52 +02:00
kexec.c PM core: rename suspend and resume functions 2009-06-12 21:32:31 +02:00
kfifo.c
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kgdb.c sysrq, intel_fb: fix sysrq g collision 2009-05-15 07:56:24 -05:00
kmod.c kmod: Release sub_info on cred allocation failure. 2009-05-26 12:11:19 -07:00
kprobes.c kprobes: fix to use text_mutex around arm/disarm kprobe 2009-05-08 16:23:48 -07:00
ksysfs.c kernel/ksysfs.c:fix dependence on CONFIG_NET 2009-01-06 10:44:31 -08:00
kthread.c tracing/events: move trace point headers into include/trace/events 2009-04-14 22:05:43 -04:00
latencytop.c sched, latencytop: incorporate review feedback from Andrew Morton 2009-02-11 10:18:04 +01:00
lockdep.c Merge branch 'linus' into tracing/core 2009-05-07 11:17:34 +02:00
lockdep_internals.h lockdep: increase MAX_LOCKDEP_ENTRIES and MAX_LOCKDEP_CHAINS 2009-05-12 19:59:52 +02:00
lockdep_proc.c lockstat: warn about disabled lock debugging 2009-02-14 23:28:28 +01:00
lockdep_states.h lockdep: move state bit definitions around 2009-02-14 23:27:59 +01:00
marker.c markers/tracpoints: fix non-modular build 2008-11-16 09:52:03 +01:00
module.c module: trim exception table on init free. 2009-06-12 21:47:04 +09:30
mutex-debug.c mutex: implement adaptive spinning 2009-01-14 18:09:02 +01:00
mutex-debug.h mutex: implement adaptive spinning 2009-01-14 18:09:02 +01:00
mutex.c Merge branch 'linus' into perfcounters/core 2009-06-11 17:55:42 +02:00
mutex.h mutex: implement adaptive spinning 2009-01-14 18:09:02 +01:00
notifier.c Merge commit 'v2.6.28-rc6' into core/debug 2008-11-26 08:22:50 +01:00
ns_cgroup.c cgroups: relax ns_can_attach checks to allow attaching to grandchild cgroups 2009-04-02 19:04:53 -07:00
nsproxy.c User namespaces: set of cleanups (v2) 2008-11-24 18:57:41 -05:00
panic.c Fix caller information for warn_slowpath_null 2009-05-16 13:41:28 -07:00
params.c module_param: allow 'bool' module_params to be bool, not just int. 2009-06-12 21:46:58 +09:30
perf_counter.c perf_counter: Add forward/backward attribute ABI compatibility 2009-06-12 14:28:52 +02:00
pid.c pids: refactor vnr/nr_ns helpers to make them safe 2009-04-02 19:05:02 -07:00
pid_namespace.c signals: zap_pid_ns_process() should use force_sig() 2009-04-02 19:04:58 -07:00
pm_qos_params.c
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posix-cpu-timers.c kernel/posix-cpu-timers.c: fix sparse warning 2009-04-30 08:08:31 +02:00
posix-timers.c [CVE-2009-0029] System call wrappers part 05 2009-01-14 14:15:20 +01:00
printk.c Merge branch 'printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-04-05 10:23:25 -07:00
profile.c x86: remove some alloc_bootmem_cpumask_var calling 2009-06-11 19:27:07 +03:00
ptrace.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6 2009-06-11 10:01:41 -07:00
rcuclassic.c kmemtrace, rcu: fix linux/rcutree.h and linux/rcuclassic.h dependencies 2009-04-03 12:23:02 +02:00
rcupdate.c RCU: Don't try and predeclare inline funcs as it upsets some versions of gcc 2009-04-15 13:55:14 -07:00
rcupreempt.c rcu: rcu_sched_grace_period(): kill the bogus flush_signals() 2009-05-05 20:28:05 +02:00
rcupreempt_trace.c "Tree RCU": scalable classic RCU implementation 2008-12-18 21:56:04 +01:00
rcutorture.c cpumask: convert rcutorture.c 2009-03-30 22:05:16 +10:30
rcutree.c rcu: Add __rcu_pending tracing to hierarchical RCU 2009-04-14 11:33:43 +02:00
rcutree.h kmemtrace, rcu: fix rcu_tree_trace.c data structure dependencies 2009-04-03 12:23:03 +02:00
rcutree_trace.c rcu: Add __rcu_pending tracing to hierarchical RCU 2009-04-14 11:33:43 +02:00
relay.c Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-04-05 11:04:19 -07:00
res_counter.c memcg: memory cgroup resource counters for hierarchy 2009-01-08 08:31:05 -08:00
resource.c Remove 'recurse into child resources' logic from 'reserve_region_with_split()' 2009-04-18 21:44:24 -07:00
rtmutex-debug.c
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rtmutex-debug.h
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rtmutex-tester.c
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rtmutex.c trivial: fix ETIMEOUT -> ETIMEDOUT typos 2009-06-12 18:01:50 +02:00
rtmutex.h
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rtmutex_common.h rt_mutex: add proxy lock routines 2009-04-06 11:14:02 +02:00
rwsem.c
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sched.c sched: export kick_process 2009-06-12 22:27:01 +09:30
sched_clock.c sched: Fix fallback sched_clock()'s offset when using jiffies 2009-05-09 10:08:19 +02:00
sched_cpupri.c sched: use slab in cpupri_init() 2009-06-11 19:27:12 +03:00
sched_cpupri.h cpumask: remove cpumask_t from core 2009-03-30 22:05:17 +10:30
sched_debug.c sched: remove unused fields from struct rq 2009-03-24 23:16:51 +01:00
sched_fair.c sched: remove redundant hierarchy walk in check_preempt_wakeup 2009-04-09 08:19:08 +02:00
sched_features.h Merge branch 'locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-03-30 17:17:35 -07:00
sched_idletask.c sched, timers: move calc_load() to scheduler 2009-05-15 15:32:45 +02:00
sched_rt.c cpumask: alloc zeroed cpumask for static cpumask_var_ts 2009-06-09 22:30:27 +09:30
sched_stats.h sched: remove unused fields from struct rq 2009-03-24 23:16:51 +01:00
seccomp.c x86-64: seccomp: fix 32/64 syscall hole 2009-03-02 15:41:30 -08:00
semaphore.c
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signal.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6 2009-06-11 10:01:41 -07:00
slow-work.c slow_work_thread() should do the exclusive wait 2009-06-11 11:26:38 -07:00
smp.c cpumask: alloc zeroed cpumask for static cpumask_var_ts 2009-06-09 22:30:27 +09:30
softirq.c Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-06-10 19:53:40 -07:00
softlockup.c softlockup: decouple hung tasks check from softlockup detection 2009-01-16 14:06:04 +01:00
spinlock.c Allow rwlocks to re-enable interrupts 2009-04-02 19:05:11 -07:00
srcu.c
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stacktrace.c stacktrace: provide save_stack_trace_tsk() weak alias 2008-12-25 11:44:43 +01:00
stop_machine.c cpumask: remove cpumask_t from core 2009-03-30 22:05:17 +10:30
sys.c Merge branch 'linus' into perfcounters/core 2009-04-29 14:47:05 +02:00
sys_ni.c Merge commit 'v2.6.29-rc2' into perfcounters/core 2009-01-21 16:37:27 +01:00
sysctl.c Merge branch 'perfcounters-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-06-11 14:01:07 -07:00
sysctl_check.c net: add ARP notify option for devices 2009-02-01 01:04:33 -08:00
taskstats.c cpumask: convert rest of files in kernel/ 2009-01-01 10:12:28 +10:30
test_kprobes.c kprobes: add tests for register_kprobes 2009-01-06 15:59:20 -08:00
time.c [CVE-2009-0029] System call wrappers part 01 2009-01-14 14:15:18 +01:00
timeconst.pl
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timer.c Merge branch 'linus' into x86/mce3 2009-06-11 23:31:52 +02:00
tracepoint.c tracepoints: dont update zero-sized tracepoint sections 2009-03-18 19:55:00 +01:00
tsacct.c Fix fixpoint divide exception in acct_update_integrals 2009-03-09 08:13:35 -07:00
uid16.c [CVE-2009-0029] System call wrappers part 19 2009-01-14 14:15:26 +01:00
up.c smp_call_function_single(): be slightly less stupid, fix #2 2009-01-12 16:04:37 +01:00
user.c Merge branch 'master' into next 2009-03-24 10:52:46 +11:00
user_namespace.c Fix recursive lock in free_uid()/free_user_ns() 2009-02-27 16:26:21 -08:00
utsname.c
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utsname_sysctl.c proc_sysctl: use CONFIG_PROC_SYSCTL around ipc and utsname proc_handlers 2009-04-02 19:05:01 -07:00
wait.c wait: don't use __wake_up_common() 2009-04-14 17:17:16 +02:00
workqueue.c ftrace, workqueuetrace: make workqueue tracepoints use TRACE_EVENT macro 2009-06-02 01:10:40 +02:00