trace_seq_reserve() allows a caller to reserve space in a trace_seq and
write directly into it. This makes it easier to export binary data to
userspace via the tracing interface, by simply filling in a struct.
Signed-off-by: NEduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

 "Because when we call ftrace_free_rec we change the rec->ip to point to the
  next record in the chain. Something is very wrong if rec->ip >= s &&
  rec->ip < e and the record is already free."

 "Note, use FTRACE_WARN_ON() macro. This way it shuts down ftrace if it is
  hit and helps to avoid further damage later."
                   -- Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NZhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Empty lines separate cpus stat. After previous
fix(trace_stat: keep original order) applied, the empty lines
are displayed at incorrect position.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: NSteven Rostedt <srostedt@redhat.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49C9F266.2060706@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: make trace_stat files show items with the original order

trace_stat tracer reverse the items, it makes the output
looks a little ugly.

Example, when we read trace_stat/workqueues, we get cpu#7's stat.
at first, and then cpu#6... cpu#0.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: NSteven Rostedt <srostedt@redhat.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49C9F23F.5040307@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: Fix incorrect way using seq_file's API

Use SEQ_START_TOKEN instead of calling ->stat_headers()
int seq_operation->start().
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: NSteven Rostedt <srostedt@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
LKML-Reference: <49C9EAE5.5070202@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

struct dyn_ftrace::ip has different usages in his lifecycle,
we use union for it. And also for struct dyn_ftrace::flags.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49C871BE.3080405@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix PID output under namespaces

When current namespace is not the global namespace,
pid read from set_ftrace_pid is no correct.

 # ~/newpid_namespace_run bash
 # echo $$
 1
 # echo 1 > set_ftrace_pid
 # cat set_ftrace_pid
 3756

Since we write virtual PID to set_ftrace_pid, we need get
virtual PID when we read it.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49C84D65.9050606@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: give user a choice to show times spent while sleeping

The user may want to see the time a function spent sleeping.
This patch adds the trace option "sleep-time" to allow that.
The "sleep-time" option is default on.

 echo sleep-time > /debug/tracing/trace_options

produces:

 ------------------------------------------
 2)  avahi-d-3428  =>    <idle>-0
 ------------------------------------------

 2)               |      finish_task_switch() {
 2)   0.621 us    |        _spin_unlock_irq();
 2)   2.202 us    |      }
 2) ! 1002.197 us |    }
 2) ! 1003.521 us |  }

where as,

 echo nosleep-time > /debug/tracing/trace_options

produces:

 0)    <idle>-0    =>  yum-upd-3416
 ------------------------------------------

 0)               |              finish_task_switch() {
 0)   0.643 us    |                _spin_unlock_irq();
 0)   2.342 us    |              }
 0) + 41.302 us   |            }
 0) + 42.453 us   |          }
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: more accurate timings

The current method of function graph tracing does not take into
account the time spent when a task is not running. This shows functions
that call schedule have increased costs:

 3) + 18.664 us   |      }
 ------------------------------------------
 3)    <idle>-0    =>  kblockd-123
 ------------------------------------------

 3)               |      finish_task_switch() {
 3)   1.441 us    |        _spin_unlock_irq();
 3)   3.966 us    |      }
 3) ! 2959.433 us |    }
 3) ! 2961.465 us |  }

This patch uses the tracepoint in the scheduling context switch to
account for time that has elapsed while a task is scheduled out.
Now we see:

 ------------------------------------------
 3)    <idle>-0    =>  edac-po-1067
 ------------------------------------------

 3)               |      finish_task_switch() {
 3)   0.685 us    |        _spin_unlock_irq();
 3)   2.331 us    |      }
 3) + 41.439 us   |    }
 3) + 42.663 us   |  }
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: prevent crash due to multiple function graph tracers

The function graph tracer can currently only handle a single tracer
being registered. If another tracer registers with the function
graph tracer it can crash the system.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

This patch move the timestamp from happening in the arch specific
code into the general code. This allows for better control by the tracer
to time manipulation.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

If the function profiler does not have any items recorded and one were
to cat the function stat file, the kernel would take a BUG with a NULL
pointer dereference.

Looking further into this, I found that returning NULL from stat_start
did not stop the stat logic, and would later call stat_next. This breaks
from the way seq_file works, so I looked into fixing the stat code.

This is where I noticed that the last next_entry is never freed.
It is allocated, and if the stat_next returns NULL, the code breaks out
of the loop, unlocks the mutex and exits. We never link the next_entry
nor do we free it. Thus it is a real memory leak.

This patch rearranges the code a bit to not only fix the memory leak,
but also to act more like seq_file where nothing is printed if there
is nothing to print. That is, stat_start returns NULL.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

commit 40ada30f ("tracing: clean up menu"),
despite the "clean up" in its purpose, introduced a behavioural
change for Kconfig symbols: we no longer able to select tracing
support on PPC32 (because IRQFLAGS_SUPPORT isn't yet implemented).

The IRQFLAGS_SUPPORT is not mandatory for most tracers, tracing core
has a special case for platforms w/o irqflags (which, by the way, has
become useless as of the commit above).

Though according to Ingo Molnar, there was periodic build failures on
weird, unmaintained architectures that had no irqflags-tracing support
and hence didn't know the raw_irqs_save/restore primitives. Thus we'd
better not enable irqflags-less tracing for all architectures.

This patch restores the old behaviour for PPC32, and thus brings the
tracing back. Other architectures can either add themselves to the
exception list or (better) implement TRACE_IRQFLAGS_SUPPORT.
Signed-off-by: NAnton Vorontsov <avorontsov@ru.mvista.com>
Acked-b: Steven Rostedt <rostedt@goodmis.org>
Cc: linuxppc-dev@ozlabs.org
LKML-Reference: <20090323220724.GA9851@oksana.dev.rtsoft.ru>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix a crash with ftrace={nop,boot} parameter

If the nop or initcall tracers are launched as boot tracers,
they will attempt to create their option directory and files.
But these tracers are registered very early and then assigned
as "boot tracers" very early if asked to.

Since they do this before debugfs has been registered (core initcall),
a crash is triggered.

Another early tracers could also come later. So we fix it by
checking if debugfs is initialized before creating the root
tracing directory.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237759847-21025-3-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup.

This patch fixes the following sparse warnings:

 kernel/trace/trace.c:385:9: warning: symbol 'trace_seq_to_buffer' was
 not declared. Should it be static?

 kernel/trace/trace_clock.c:29:13: warning: symbol 'trace_clock_local'
 was not declared. Should it be static?

 kernel/trace/trace_clock.c:54:13: warning: symbol 'trace_clock' was not
 declared. Should it be static?

 kernel/trace/trace_clock.c:74:13: warning: symbol 'trace_clock_global'
 was not declared. Should it be static?
Signed-off-by: NDmitri Vorobiev <dmitri.vorobiev@movial.com>
LKML-Reference: <1237741871-5827-4-git-send-email-dmitri.vorobiev@movial.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Instead of using ftrace_dump_on_oops, it's far more convenient
to have the trace leading up to a self-test failure available
in /debug/tracing/trace.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237694675-23509-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: detect tracing related hangs

Sometimes, with some configs, the function graph tracer can make
the timer interrupt too much slow, hanging the kernel in an endless
loop of timer interrupts servicing.

As suggested by Ingo, this patch brings a watchdog which stops the
selftest after a defined number of functions traced, definitely
disabling this tracer.

For those who want to debug the cause of the function graph trace
hang, you can pass the ftrace_dump_on_oops kernel parameter to dump
the traces after this hang detection.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237694675-23509-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: remove a section warning

CONFIG_DEBUG_SECTION_MISMATCH raises the following warning on -tip:

  WARNING: kernel/trace/built-in.o(.text+0x5bc5): Section mismatch in
  reference from the function ring_buffer_alloc() to the function
  .cpuinit.text:rb_cpu_notify()
  The function ring_buffer_alloc() references
  the function __cpuinit rb_cpu_notify().

This is actually harmless. The code in the ring buffer don't build
rb_cpu_notify and other cpu hotplug stuffs when !CONFIG_HOTPLUG_CPU
so we have no risk to reference freed memory here (it would even
be harmless if we unconditionally build it because register_cpu_notifier
would do nothing when !CONFIG_HOTPLUG_CPU.

But since ring_buffer_alloc() can be called everytime, we don't want it
to be annotated with __cpuinit so we drop the __cpuinit from
rb_cpu_notify.

This is not a waste of memory because it is only defined and used on
CONFIG_HOTPLUG_CPU.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237606416-22268-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: build fix on SH !CONFIG_MMU

Stephen Rothwell reported this linux-next build failure on the SH
architecture:

  kernel/built-in.o: In function `disable_all_kprobes':
  kernel/kprobes.c:1382: undefined reference to `text_mutex'
  [...]

And observed:

| Introduced by commit 4460fdad ("tracing,
| Text Edit Lock - kprobes architecture independent support") from the
| tracing tree.  text_mutex is defined in mm/memory.c which is only built
| if CONFIG_MMU is defined, which is not true for sh allmodconfig.

Move this lock to kernel/extable.c (which is already home to various
kernel text related routines), which file is always built-in.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
LKML-Reference: <20090320110602.86351a91.sfr@canb.auug.org.au>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: new tracing infrastructure feature

Provide infrastructure to generate software perf counter events
from tracepoints.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090319194233.557364871@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: widen user-space visibe event IDs to all events

Previously only TRACE_EVENT events got ids, because only they
generated raw output which needs to be demuxed from the trace.

In order to provide a unique ID for each event, register everybody,
regardless.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090319194233.464914218@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Since not every event has a format file to read the id from,
expose it explicitly in a separate file.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090319194233.372534033@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

With the added TRACE_EVENT macro, the events no longer appear in
the function graph tracer. This was because the function graph
did not know how to display the entries. The graph tracer was
only aware of its own entries and the printk entries.

By using the event call back feature, the graph tracer can now display
the events.

 # echo irq > /debug/tracing/set_event

Which can show:

 0)               |          handle_IRQ_event() {
 0)               |            /* irq_handler_entry: irq=48 handler=eth0 */
 0)               |            e1000_intr() {
 0)   0.926 us    |              __napi_schedule();
 0)   3.888 us    |            }
 0)               |            /* irq_handler_exit: irq=48 return=handled */
 0)   0.655 us    |            runqueue_is_locked();
 0)               |            __wake_up() {
 0)   0.831 us    |              _spin_lock_irqsave();

The irq entry and exit events show up as comments.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

The function depth in trace_printk was to facilitate the function
graph output. Now that the function graph calculates the depth within
the trace output, we no longer need to record the depth when the
trace_printk is called.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Currently, the function graph tracer depends on the trace_printk
to record the depth. All the information is already there in the trace
to calculate function depth, with the exception of having the printk
be the first item. But as soon as a entry or exit is reached, then
we know the depth.

This patch changes the iter->private data from recording a per cpu
last_pid, to a structure that holds both the last_pid and the current
depth. This data is used to determine the function depth for the
printks.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

This patch makes print_printk_msg_only and print_bprintk_msg_only
global for other functions to use. It also renames them by adding
a "trace_" to the beginning to avoid namespace collisions.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: fix warning with irqsoff tracer

The ring buffer allocates its buffers on pre-smp time (early_initcall).
It means that, at first, only the boot cpu buffer is allocated and
the ring-buffer cpumask only has the boot cpu set (cpu_online_mask).

Later, the secondary cpu will show up and the ring-buffer will be notified
about this event: the appropriate buffer will be allocated and the cpumask
will be updated.

Unfortunately, if !CONFIG_CPU_HOTPLUG, the ring-buffer will not be
notified about the secondary cpus, meaning that the cpumask will have
only the cpu boot set, and only one cpu buffer allocated.

We fix that by using cpu_possible_mask if !CONFIG_CPU_HOTPLUG.

This patch fixes the following warning with irqsoff tracer running:

[  169.317794] WARNING: at kernel/trace/trace.c:466 update_max_tr_single+0xcc/0xf3()
[  169.318002] Hardware name: AMILO Li 2727
[  169.318002] Modules linked in:
[  169.318002] Pid: 5624, comm: bash Not tainted 2.6.29-rc8-tip-02636-g6aafa6c #11
[  169.318002] Call Trace:
[  169.318002]  [<ffffffff81036182>] warn_slowpath+0xea/0x13d
[  169.318002]  [<ffffffff8100b9d6>] ? ftrace_call+0x5/0x2b
[  169.318002]  [<ffffffff8100b9d6>] ? ftrace_call+0x5/0x2b
[  169.318002]  [<ffffffff8100b9d1>] ? ftrace_call+0x0/0x2b
[  169.318002]  [<ffffffff8101ef10>] ? ftrace_modify_code+0xa9/0x108
[  169.318002]  [<ffffffff8106e27f>] ? trace_hardirqs_off+0x25/0x27
[  169.318002]  [<ffffffff8149afe7>] ? _spin_unlock_irqrestore+0x1f/0x2d
[  169.318002]  [<ffffffff81064f52>] ? ring_buffer_reset_cpu+0xf6/0xfb
[  169.318002]  [<ffffffff8106637c>] ? ring_buffer_reset+0x36/0x48
[  169.318002]  [<ffffffff8106aeda>] update_max_tr_single+0xcc/0xf3
[  169.318002]  [<ffffffff8100bc17>] ? sysret_check+0x22/0x5d
[  169.318002]  [<ffffffff8106e3ea>] stop_critical_timing+0x142/0x204
[  169.318002]  [<ffffffff8106e4cf>] trace_hardirqs_on_caller+0x23/0x25
[  169.318002]  [<ffffffff8149ac28>] trace_hardirqs_on_thunk+0x3a/0x3c
[  169.318002]  [<ffffffff8100bc17>] ? sysret_check+0x22/0x5d
[  169.318002] ---[ end trace db76cbf775a750cf ]---

Because this tracer may try to swap two cpu ring buffers for an
unregistered cpu on the ring buffer.

This patch might also fix a fair loss of traces due to unallocated buffers
for secondary cpus.
Reported-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-b: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237470453-5427-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: clean up

The prologue of the function graph entry, return and comments all
start out pretty much the same. Each of these duplicate code and
do so slightly differently.

This patch consolidates the printing of the pid, absolute time,
cpu and proc (and for entry, the interrupt).
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Zero-sized tracepoint sections can occur if tracing is enabled but
no tracepoint is defined. Do not emit a warning in that case.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
LKML-Reference: <1237394936.3132.1.camel@localhost.localdomain>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Change this crash:

 BUG: unable to handle kernel NULL pointer dereference at (null)
 IP: [<ffffffff8107d4de>] tracepoint_update_probe_range+0x1f/0x9b
 PGD 13d5fb067 PUD 13d688067 PMD 0
 Oops: 0000 [#1] SMP

To a more debuggable WARN_ONCE().
Signed-off-by: NJaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237394936.3132.1.camel@localhost.localdomain>
[ moved the check outside the lock and added a WARN_ON(). ]
Signed-off-by: NIngo Molnar <mingo@elte.hu>

There is currently no easy way to clear the trace buffer. Currently
the only way is to change the current tracer.

This patch lets the user clear the trace buffer by simply writing
into the trace files.

 echo > /debug/tracing/trace

or to clear a single cpu (i.e. for CPU 1):

 echo > /debug/tracing/per_cpu/cpu1/trace
Requested-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Fix locking imbalance in kretprobes:

=====================================
[ BUG: bad unlock balance detected! ]
-------------------------------------
kthreadd/2 is trying to release lock (&rp->lock) at:
[<c06b3080>] pre_handler_kretprobe+0xea/0xf4
but there are no more locks to release!

other info that might help us debug this:
1 lock held by kthreadd/2:
 #0:  (rcu_read_lock){..--}, at: [<c06b2b24>] __atomic_notifier_call_chain+0x0/0x5a

stack backtrace:
Pid: 2, comm: kthreadd Not tainted 2.6.29-rc8 #1
Call Trace:
 [<c06ae498>] ? printk+0xf/0x17
 [<c06b3080>] ? pre_handler_kretprobe+0xea/0xf4
 [<c044ce6c>] print_unlock_inbalance_bug+0xc3/0xce
 [<c0444d4b>] ? clocksource_read+0x7/0xa
 [<c04450a4>] ? getnstimeofday+0x5f/0xf6
 [<c044a9ca>] ? register_lock_class+0x17/0x293
 [<c044b72c>] ? mark_lock+0x1e/0x30b
 [<c0448956>] ? tick_dev_program_event+0x4a/0xbc
 [<c0498100>] ? __slab_alloc+0xa5/0x415
 [<c06b2fbe>] ? pre_handler_kretprobe+0x28/0xf4
 [<c06b3080>] ? pre_handler_kretprobe+0xea/0xf4
 [<c044cf1b>] lock_release_non_nested+0xa4/0x1a5
 [<c06b3080>] ? pre_handler_kretprobe+0xea/0xf4
 [<c044d15d>] lock_release+0x141/0x166
 [<c06b07dd>] _spin_unlock_irqrestore+0x19/0x50
 [<c06b3080>] pre_handler_kretprobe+0xea/0xf4
 [<c06b20b5>] kprobe_exceptions_notify+0x1c9/0x43e
 [<c06b2b02>] notifier_call_chain+0x26/0x48
 [<c06b2b5b>] __atomic_notifier_call_chain+0x37/0x5a
 [<c06b2b24>] ? __atomic_notifier_call_chain+0x0/0x5a
 [<c06b2b8a>] atomic_notifier_call_chain+0xc/0xe
 [<c0442d0d>] notify_die+0x2d/0x2f
 [<c06b0f9c>] do_int3+0x1f/0x71
 [<c06b0e84>] int3+0x2c/0x34
 [<c042d476>] ? do_fork+0x1/0x288
 [<c040221b>] ? kernel_thread+0x71/0x79
 [<c043ed1b>] ? kthread+0x0/0x60
 [<c043ed1b>] ? kthread+0x0/0x60
 [<c04040b8>] ? kernel_thread_helper+0x0/0x10
 [<c043ec7f>] kthreadd+0xac/0x148
 [<c043ebd3>] ? kthreadd+0x0/0x148
 [<c04040bf>] kernel_thread_helper+0x7/0x10
Signed-off-by: NAnanth N Mavinakayanahalli <ananth@in.ibm.com>
Tested-by: NBharata B Rao <bharata@linux.vnet.ibm.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@kernel.org> [2.6.29.x, 2.6.28.x, 2.6.27.x]
LKML-Reference: <20090318113621.GB4129@in.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix a selftest warning

In some cases, it's possible to see the following warning on irqsoff
tracer selftest:

[    4.640003] Testing tracer irqsoff: <4>------------[ cut here ]------------
[    4.653562] WARNING: at kernel/trace/trace.c:458 update_max_tr_single+0x9a/0xc4()
[    4.660000] Hardware name: System Product Name
[    4.660000] Modules linked in:
[    4.660000] Pid: 301, comm: kstop/1 Not tainted 2.6.29-rc8-tip #35837
[    4.660000] Call Trace:
[    4.660000]  [<4014b588>] warn_slowpath+0x79/0x8f
[    4.660000]  [<402d6949>] ? put_dec+0x64/0x6b
[    4.660000]  [<40162b56>] ? getnstimeofday+0x58/0xdd
[    4.660000]  [<40162210>] ? clocksource_read+0x3/0xf
[    4.660000]  [<4015eb44>] ? ktime_set+0x8/0x34
[    4.660000]  [<4014101a>] ? balance_runtime+0x8/0x56
[    4.660000]  [<405f6f11>] ? _spin_lock+0x3/0x10
[    4.660000]  [<4011f643>] ? ftrace_call+0x5/0x8
[    4.660000]  [<4015d0f1>] ? task_cputime_zero+0x3/0x27
[    4.660000]  [<40190ee7>] ? cpupri_set+0x90/0xcb
[    4.660000]  [<405f7208>] ? _spin_lock_irqsave+0x22/0x34
[    4.660000]  [<40190f12>] ? cpupri_set+0xbb/0xcb
[    4.660000]  [<405f7151>] ? _spin_unlock_irqrestore+0x23/0x35
[    4.660000]  [<4018493f>] ? ring_buffer_reset_cpu+0x27/0x51
[    4.660000]  [<405f7208>] ? _spin_lock_irqsave+0x22/0x34
[    4.660000]  [<40184962>] ? ring_buffer_reset_cpu+0x4a/0x51
[    4.660000]  [<405f7151>] ? _spin_unlock_irqrestore+0x23/0x35
[    4.660000]  [<4018cc29>] ? trace_hardirqs_off+0x1a/0x1c
[    4.660000]  [<405f7151>] ? _spin_unlock_irqrestore+0x23/0x35
[    4.660000]  [<40184962>] ? ring_buffer_reset_cpu+0x4a/0x51
[    4.660000]  [<401850f3>] ? cpumask_next+0x15/0x18
[    4.660000]  [<4018a41f>] update_max_tr_single+0x9a/0xc4
[    4.660000]  [<4014e5fe>] ? exit_notify+0x16/0xf2
[    4.660000]  [<4018cd13>] check_critical_timing+0xcc/0x11e
[    4.660000]  [<4014e5fe>] ? exit_notify+0x16/0xf2
[    4.660000]  [<4014e5fe>] ? exit_notify+0x16/0xf2
[    4.660000]  [<4018cdf1>] stop_critical_timing+0x8c/0x9f
[    4.660000]  [<4014e5c4>] ? forget_original_parent+0xac/0xd0
[    4.660000]  [<4018ce3a>] trace_hardirqs_on+0x1a/0x1c
[    4.660000]  [<4014e5c4>] forget_original_parent+0xac/0xd0
[    4.660000]  [<4014e5fe>] exit_notify+0x16/0xf2
[    4.660000]  [<4014e8a5>] do_exit+0x1cb/0x225
[    4.660000]  [<4015c72b>] ? kthread+0x0/0x69
[    4.660000]  [<4011f61d>] kernel_thread_helper+0xd/0x10
[    4.660000] ---[ end trace a7919e7f17c0a725 ]---
[    4.660164] .. no entries found ..FAILED!

During the selftest of irqsoff tracer, we do that:

	/* disable interrupts for a bit */
	local_irq_disable();
	udelay(100);
	local_irq_enable();
	/* stop the tracing. */
	tracing_stop();
	/* check both trace buffers */
	ret = trace_test_buffer(tr, NULL);

If a callsite performs a new max delay with irqs off just after
tracing_stop, update_max_tr_single() -> ring_buffer_swap_cpu()
will be called with the buffers disabled by tracing_stop(), hence
the warning, then ring_buffer_swap_cpu() return -EAGAIN and
update_max_tr_single() complains.

Fix it by also stopping the tracer before stopping the tracing globally.
A similar situation can happen with preemptoff and preemptirqsoff tracers
where we apply the same fix.
Reported-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237325938-5240-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix command line to pid mapping

map_cmdline_to_pid[] is checked in trace_save_cmdline(), but never
updated. This results in stale pid to command line mappings and the
tracer output will associate the wrong comm string.
Signed-off-by: NCarsten Emde <Carsten.Emde@osadl.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: prevent stale command line output

In case there is no valid command line mapping for a pid
trace_find_cmdline() returns without updating the comm buffer. The
trace dump keeps the previous entry which results in confusing trace
output:

     <idle>-0     [000]   280.702056 ....
     <idle>-23456 [000]   280.702080 ....

Update the comm buffer with "<...>" when no mapping is found.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

The command line recorder uses (unsigned) -1 to mark non mapped
entries in the pid to command line maps. The validity check is
completely unintuitive: idx >= SAVED_CMDLINES

There is no need for such casting games. Use a constant to mark
unmapped entries and check for that constant to make the code readable
and understandable.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: prevent overwrite of command line entries

When the tracer is stopped the command line recording continues to
record. The check for tracing_is_on() is not sufficient here as the
ringbuffer status is not affected by setting
debug/tracing/tracing_enabled to 0. On a non idle system this can
result in the loss of the command line information for the stopped
trace, which makes the trace harder to read and analyse.

Check tracer_enabled to allow further recording.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The start/stop methods of a tracer should be able to be executed
in all contexts. This patch converts the power tracer to do so.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

The stopping and starting of a tracer should be light weight and
be able to be called in all contexts. The sched_switch grabbed
mutexes in the start/stop functions. This patch changes it to a
simple variable, on/off.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: feature to allow better serialized clock

This patch adds an option called "global-clock" that will allow
the tracer to switch to a slower but more accurate (across CPUs)
clock.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>