In case the the graph tracer (CONFIG_FUNCTION_GRAPH_TRACER) or even the
function tracer (CONFIG_FUNCTION_TRACER) are not set, the latency tracers
do not display proper latency header.

The involved/fixed latency tracers are:
        wakeup_rt
        wakeup
        preemptirqsoff
        preemptoff
        irqsoff

The patch adds proper handling of tracer configuration options for latency
tracers, and displaying correct header info accordingly.

* The current output (for wakeup tracer) with both graph and function
  tracers disabled is:

  # tracer: wakeup
  #
    <idle>-0       0d.h5    1us+:      0:120:R   + [000]     7:  0:R watchdog/0
    <idle>-0       0d.h5    3us+: ttwu_do_activate.clone.1 <-try_to_wake_up
    ...

* The fixed output is:

  # tracer: wakeup
  #
  # wakeup latency trace v1.1.5 on 3.1.0-tip+
  # --------------------------------------------------------------------
  # latency: 55 us, #4/4, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
  #    -----------------
  #    | task: migration/0-6 (uid:0 nice:0 policy:1 rt_prio:99)
  #    -----------------
  #
  #                  _------=> CPU#
  #                 / _-----=> irqs-off
  #                | / _----=> need-resched
  #                || / _---=> hardirq/softirq
  #                ||| / _--=> preempt-depth
  #                |||| /     delay
  #  cmd     pid   ||||| time  |   caller
  #     \   /      |||||  \    |   /
       cat-1129    0d..4    1us :   1129:120:R   + [000]     6:  0:R migration/0
       cat-1129    0d..4    2us+: ttwu_do_activate.clone.1 <-try_to_wake_up

* The current output (for wakeup tracer) with only function
  tracer enabled is:

  # tracer: wakeup
  #
       cat-1140    0d..4    1us+:   1140:120:R   + [000]     6:  0:R migration/0
       cat-1140    0d..4    2us : ttwu_do_activate.clone.1 <-try_to_wake_up

* The fixed output is:
  # tracer: wakeup
  #
  # wakeup latency trace v1.1.5 on 3.1.0-tip+
  # --------------------------------------------------------------------
  # latency: 207 us, #109/109, CPU#1 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2)
  #    -----------------
  #    | task: watchdog/1-12 (uid:0 nice:0 policy:1 rt_prio:99)
  #    -----------------
  #
  #                  _------=> CPU#
  #                 / _-----=> irqs-off
  #                | / _----=> need-resched
  #                || / _---=> hardirq/softirq
  #                ||| / _--=> preempt-depth
  #                |||| /     delay
  #  cmd     pid   ||||| time  |   caller
  #     \   /      |||||  \    |   /
    <idle>-0       1d.h5    1us+:      0:120:R   + [001]    12:  0:R watchdog/1
    <idle>-0       1d.h5    3us : ttwu_do_activate.clone.1 <-try_to_wake_up

Link: http://lkml.kernel.org/r/20111107150849.GE1807@m.brq.redhat.com

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

If the set_ftrace_filter is cleared by writing just whitespace to
it, then the filter hash refcounts will be decremented but not
updated. This causes two bugs:

1) No functions will be enabled for tracing when they all should be

2) If the users clears the set_ftrace_filter twice, it will crash ftrace:

------------[ cut here ]------------
WARNING: at /home/rostedt/work/git/linux-trace.git/kernel/trace/ftrace.c:1384 __ftrace_hash_rec_update.part.27+0x157/0x1a7()
Modules linked in:
Pid: 2330, comm: bash Not tainted 3.1.0-test+ #32
Call Trace:
 [<ffffffff81051828>] warn_slowpath_common+0x83/0x9b
 [<ffffffff8105185a>] warn_slowpath_null+0x1a/0x1c
 [<ffffffff810ba362>] __ftrace_hash_rec_update.part.27+0x157/0x1a7
 [<ffffffff810ba6e8>] ? ftrace_regex_release+0xa7/0x10f
 [<ffffffff8111bdfe>] ? kfree+0xe5/0x115
 [<ffffffff810ba51e>] ftrace_hash_move+0x2e/0x151
 [<ffffffff810ba6fb>] ftrace_regex_release+0xba/0x10f
 [<ffffffff8112e49a>] fput+0xfd/0x1c2
 [<ffffffff8112b54c>] filp_close+0x6d/0x78
 [<ffffffff8113a92d>] sys_dup3+0x197/0x1c1
 [<ffffffff8113a9a6>] sys_dup2+0x4f/0x54
 [<ffffffff8150cac2>] system_call_fastpath+0x16/0x1b
---[ end trace 77a3a7ee73794a02 ]---

Link: http://lkml.kernel.org/r/20111101141420.GA4918@debianReported-by: NRabin Vincent <rabin@rab.in>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

A forced undef of a config value was used for testing and was
accidently left in during the final commit. This causes x86 to
run slower than needed while running function tracing as well
as causes the function graph selftest to fail when DYNMAIC_FTRACE
is not set. This is because the code in MCOUNT expects the ftrace
code to be processed with the config value set that happened to
be forced not set.

The forced config option was left in by:
    commit 6331c28c
    ftrace: Fix dynamic selftest failure on some archs

Link: http://lkml.kernel.org/r/20111102150255.GA6973@debian

Cc: stable@vger.kernel.org
Reported-by: NRabin Vincent <rabin@rab.in>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

The system filter can be used to set multiple event filters that
exist within the system. But currently it displays the last filter
written that does not necessarily correspond to the filters within
the system. The system filter itself is not used to filter any events.
The system filter is just a means to set filters of the events within
it.

Because this causes an ambiguous state when the system filter reads
a filter string but the events within the system have different strings
it is best to just show a boiler plate:

 ### global filter ###
 # Use this to set filters for multiple events.
 # Only events with the given fields will be affected.
 # If no events are modified, an error message will be displayed here.

If an error occurs while writing to the system filter, the system
filter will replace the boiler plate with the error message as it
currently does.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Though not all events have field 'prev_pid', it was allowed to do this:

  # echo 'prev_pid == 100' > events/sched/filter

but commit 75b8e982 (tracing/filter: Swap
entire filter of events) broke it without any reason.

Link: http://lkml.kernel.org/r/4EAF46CF.8040408@cn.fujitsu.comSigned-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

These files were getting <linux/module.h> via an implicit non-obvious
path, but we want to crush those out of existence since they cost
time during compiles of processing thousands of lines of headers
for no reason.  Give them the lightweight header that just contains
the EXPORT_SYMBOL infrastructure.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

Fix a bug introduced by e9dbfae5, which prevents event_subsystem from
ever being released.

Ref_count was added to keep track of subsystem users, not for counting
events.  Subsystem is created with ref_count = 1, so there is no need to
increment it for every event, we have nr_events for that.  Fix this by
touching ref_count only when we actually have a new user -
subsystem_open().

Cc: stable@vger.kernel.org
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>
Link: http://lkml.kernel.org/r/1320052062-7846-1-git-send-email-idryomov@gmail.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

These files are doing things like module_put and try_module_get
so they need to call out the module.h for explicit inclusion,
rather than getting it via <linux/device.h> which we ideally want
to remove the module.h inclusion from.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

The trace_pipe_raw handler holds a cached page from the time the file
is opened to the time it is closed. The cached page is used to handle
the case of the user space buffer being smaller than what was read from
the ring buffer. The left over buffer is held in the cache so that the
next read will continue where the data left off.

After EOF is returned (no more data in the buffer), the index of
the cached page is set to zero. If a user app reads the page again
after EOF, the check in the buffer will see that the cached page
is less than page size and will return the cached page again. This
will cause reading the trace_pipe_raw again after EOF to return
duplicate data, making the output look like the time went backwards
but instead data is just repeated.

The fix is to not reset the index right after all data is read
from the cache, but to reset it after all data is read and more
data exists in the ring buffer.

Cc: stable <stable@kernel.org>
Reported-by: NJeremy Eder <jeder@redhat.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

tracing_enabled option is deprecated.
To start/stop tracing, write to /sys/kernel/debug/tracing/tracing_on
without tracing_enabled. This patch is based on Linux 3.1.0-rc1
Signed-off-by: NGeunsik Lim <geunsik.lim@samsung.com>
Link: http://lkml.kernel.org/r/1313127022-23830-1-git-send-email-leemgs1@gmail.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

When doing intense tracing, the kmalloc inside trace_marker can
introduce side effects to what is being traced.

As trace_marker() is used by userspace to inject data into the
kernel ring buffer, it needs to do so with the least amount
of intrusion to the operations of the kernel or the user space
application.

As the ring buffer is designed to write directly into the buffer
without the need to make a temporary buffer, and userspace already
went through the hassle of knowing how big the write will be,
we can simply pin the userspace pages and write the data directly
into the buffer. This improves the impact of tracing via trace_marker
tremendously!

Thanks to Peter Zijlstra and Thomas Gleixner for pointing out the
use of get_user_pages_fast() and kmap_atomic().
Suggested-by: NThomas Gleixner <tglx@linutronix.de>
Suggested-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

As the function tracer is very intrusive, lots of self checks are
performed on the tracer and if something is found to be strange
it will shut itself down keeping it from corrupting the rest of the
kernel. This shutdown may still allow functions to be traced, as the
tracing only stops new modifications from happening. Trying to stop
the function tracer itself can cause more harm as it requires code
modification.

Although a WARN_ON() is executed, a user may not notice it. To help
the user see that something isn't right with the tracing of the system
a big warning is added to the output of the tracer that lets the user
know that their data may be incomplete.
Reported-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Fix kprobe-tracer not to delete a probe if the probe is in use.
In that case, delete operation will return -EBUSY.

This bug can cause a kernel panic if enabled probes are deleted
during perf record.

(Add some probes on functions)
sh-4.2# perf probe --del probe:\*
sh-4.2# exit
(kernel panic)

This is originally reported on the fedora bugzilla:

 https://bugzilla.redhat.com/show_bug.cgi?id=742383

I've also checked that this problem doesn't happen on
tracepoints when module removing because perf event
locks target module.

$ sudo ./perf record -e xfs:\* -aR sh
sh-4.2# rmmod xfs
ERROR: Module xfs is in use
sh-4.2# exit
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.203 MB perf.data (~8862 samples) ]
Signed-off-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: stable@kernel.org
Link: http://lkml.kernel.org/r/20111004104438.14591.6553.stgit@fedora15Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Do not build kernel/trace/rpm-traces.c if CONFIG_PM_RUNTIME is not
set, which avoids a build failure.

[rjw: Added the changelog and modified the subject slightly.]
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

This patch introduces 3 trace points to prepare for tracing
rpm_idle/rpm_suspend/rpm_resume functions, so we can use these
trace points to replace the current dev_dbg().
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

If irqs are disabled when preemption count reaches zero, the
preemptirqsoff tracer should not flag that as the end.

When interrupts are enabled and preemption count is not zero
the preemptirqsoff correctly continues its tracing.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

When debugging tight race conditions, it can be helpful to have a
synchronized tracing method. Although in most cases the global clock
provides this functionality, if timings is not the issue, it is more
comforting to know that the order of events really happened in a precise
order.

Instead of using a clock, add a "counter" that is simply an incrementing
atomic 64bit counter that orders the events as they are perceived to
happen.

The trace_clock_counter() is added from the attempt by Peter Zijlstra
trying to convert the trace_clock_global() to it. I took Peter's counter
code and made trace_clock_counter() instead, and added it to the choice
of clocks. Just echo counter > /debug/tracing/trace_clock to activate
it.
Requested-by: NThomas Gleixner <tglx@linutronix.de>
Requested-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-By: NValdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

The tracing locks can be taken in atomic context and therefore
cannot be preempted on -rt - annotate it.

In mainline this change documents the low level nature of
the lock - otherwise there's no functional difference. Lockdep
and Sparse checking will work as usual.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The stats file under per_cpu folder provides the number of entries,
overruns and other statistics about the CPU ring buffer. However, the
numbers do not provide any indication of how full the ring buffer is in
bytes compared to the overall size in bytes. Also, it is helpful to know
the rate at which the cpu buffer is filling up.

This patch adds an entry "bytes: " in printed stats for per_cpu ring
buffer which provides the actual bytes consumed in the ring buffer. This
field includes the number of bytes used by recorded events and the
padding bytes added when moving the tail pointer to next page.

It also adds the following time stamps:
"oldest event ts:" - the oldest timestamp in the ring buffer
"now ts:"  - the timestamp at the time of reading

The field "now ts" provides a consistent time snapshot to the userspace
when being read. This is read from the same trace clock used by tracing
event timestamps.

Together, these values provide the rate at which the buffer is filling
up, from the formula:
bytes / (now_ts - oldest_event_ts)
Signed-off-by: NVaibhav Nagarnaik <vnagarnaik@google.com>
Cc: Michael Rubin <mrubin@google.com>
Cc: David Sharp <dhsharp@google.com>
Link: http://lkml.kernel.org/r/1313531179-9323-3-git-send-email-vnagarnaik@google.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

The current file "buffer_size_kb" reports the size of per-cpu buffer and
not the overall memory allocated which could be misleading. A new file
"buffer_total_size_kb" adds up all the enabled CPU buffer sizes and
reports it. This is only a readonly entry.
Signed-off-by: NVaibhav Nagarnaik <vnagarnaik@google.com>
Cc: Michael Rubin <mrubin@google.com>
Cc: David Sharp <dhsharp@google.com>
Link: http://lkml.kernel.org/r/1313531179-9323-2-git-send-email-vnagarnaik@google.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

The self testing for event filters does not really need preemption
disabled as there are no races at the time of testing, but the functions
it calls uses rcu_dereference_sched() which will complain if preemption
is not disabled.

Cc: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Adding automated tests running as late_initcall. Tests are
compiled in with CONFIG_FTRACE_STARTUP_TEST option.

Adding test event "ftrace_test_filter" used to simulate
filter processing during event occurance.

String filters are compiled and tested against several
test events with different values.

Also testing that evaluation of explicit predicates is ommited
due to the lazy filter evaluation.
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1313072754-4620-11-git-send-email-jolsa@redhat.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

Changing filter_match_preds function to use unified predicates tree
processing.
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1313072754-4620-10-git-send-email-jolsa@redhat.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

Changing fold_pred_tree function to use unified predicates tree
processing.
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1313072754-4620-9-git-send-email-jolsa@redhat.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

Changing fold_pred_tree function to use unified predicates tree
processing.
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1313072754-4620-8-git-send-email-jolsa@redhat.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

Changing count_leafs function to use unified predicates tree
processing.
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1313072754-4620-7-git-send-email-jolsa@redhat.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

Adding walk_pred_tree function to be used for walking throught
the filter predicates.

For each predicate the callback function is called, allowing
users to add their own functionality or customize their way
through the filter predicates.

Changing check_pred_tree function to use walk_pred_tree.
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1313072754-4620-6-git-send-email-jolsa@redhat.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

We dont need to perform lookup through the ftrace_events list,
instead we can use the 'tp_event' field.

Each perf_event contains tracepoint event field 'tp_event', which
got initialized during the tracepoint event initialization.
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1313072754-4620-5-git-send-email-jolsa@redhat.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

The field_name was used just for finding event's fields. This way we
don't need to care about field_name allocation/free.
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1313072754-4620-4-git-send-email-jolsa@redhat.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

Making the code cleaner by having one function to fully prepare
the predicate (create_pred), and another to add the predicate to
the filter (filter_add_pred).

As a benefit, this way the dry_run flag stays only inside the
replace_preds function and is not passed deeper.
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1313072754-4620-3-git-send-email-jolsa@redhat.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

Don't dynamically allocate filter_pred struct, use static memory.
This way we can get rid of the code managing the dynamic filter_pred
struct object.

The create_pred function integrates create_logical_pred function.
This way the static predicate memory is returned only from
one place.
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1313072754-4620-2-git-send-email-jolsa@redhat.comSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

Add FLUSH/FUA support to blktrace. As FLUSH precedes WRITE and/or
FUA follows WRITE, use the same 'F' flag for both cases and
distinguish them by their (relative) position. The end results
look like (other flags might be shown also):

 - WRITE:            W
 - WRITE_FLUSH:      FW
 - WRITE_FUA:        WF
 - WRITE_FLUSH_FUA:  FWF

Note that we reuse TC_BARRIER due to lack of bit space of act_mask
so that the older versions of blktrace tools will report flush
requests as barriers from now on.

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: NNamhyung Kim <namhyung@gmail.com>
Reviewed-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

gcc incorrectly states that the variable "fmt" is uninitialized when
CC_OPITMIZE_FOR_SIZE is set.

Instead of just blindly setting fmt to NULL, the code is cleaned up
a little to be a bit easier for humans to follow, as well as gcc
to know the variables are initialized.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: NArun Sharma <asharma@fb.com>
Reviewed-by: NEric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

What was scheduled to be 2.6.41 is now going to be 3.1 .
Signed-off-by: NJesper Juhl <jj@chaosbits.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1107250929370.8080@swampdragon.chaosbits.netSigned-off-by: NIngo Molnar <mingo@elte.hu>

Since the address of a module-local variable can only be
solved after the target module is loaded, the symbol
fetch-argument should be updated when loading target
module.
Signed-off-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lkml.kernel.org/r/20110627072703.6528.75042.stgit@fedora15Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

To support probing module init functions, kprobe-tracer allows
user to define a probe on non-existed function when it is given
with a module name. This also enables user to set a probe on
a function on a specific module, even if a same name (but different)
function is locally defined in another module.

The module name must be in the front of function name and separated
by a ':'. e.g. btrfs:btrfs_init_sysfs
Signed-off-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lkml.kernel.org/r/20110627072656.6528.89970.stgit@fedora15Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Merge redundant enable/disable functions into enable_trace_probe()
and disable_trace_probe().
Signed-off-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: yrl.pp-manager.tt@hitachi.com
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Link: http://lkml.kernel.org/r/20110627072644.6528.26910.stgit@fedora15

[ converted kprobe selftest to use  enable_trace_probe ]
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Enabling function tracer to trace all functions, then load a module and
then disable function tracing will cause ftrace to fail.

This can also happen by enabling function tracing on the command line:

  ftrace=function

and during boot up, modules are loaded, then you disable function tracing
with 'echo nop > current_tracer' you will trigger a bug in ftrace that
will shut itself down.

The reason is, the new ftrace code keeps ref counts of all ftrace_ops that
are registered for tracing. When one or more ftrace_ops are registered,
all the records that represent the functions that the ftrace_ops will
trace have a ref count incremented. If this ref count is not zero,
when the code modification runs, that function will be enabled for tracing.
If the ref count is zero, that function will be disabled from tracing.

To make sure the accounting was working, FTRACE_WARN_ON()s were added
to updating of the ref counts.

If the ref count hits its max (> 2^30 ftrace_ops added), or if
the ref count goes below zero, a FTRACE_WARN_ON() is triggered which
disables all modification of code.

Since it is common for ftrace_ops to trace all functions in the kernel,
instead of creating > 20,000 hash items for the ftrace_ops, the hash
count is just set to zero, and it represents that the ftrace_ops is
to trace all functions. This is where the issues arrise.

If you enable function tracing to trace all functions, and then add
a module, the modules function records do not get the ref count updated.
When the function tracer is disabled, all function records ref counts
are subtracted. Since the modules never had their ref counts incremented,
they go below zero and the FTRACE_WARN_ON() is triggered.

The solution to this is rather simple. When modules are loaded, and
their functions are added to the the ftrace pool, look to see if any
ftrace_ops are registered that trace all functions. And for those,
update the ref count for the module function records.
Reported-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Rename probe_* to trace_probe_* for avoiding namespace
confliction. This also fixes improper names of find_probe_event()
and cleanup_all_probes() to find_trace_probe() and
release_all_trace_probes() respectively.
Signed-off-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20110627072636.6528.60374.stgit@fedora15Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>