Right now all tracers must manage their own trace buffers. This was
to enforce tracers to be independent in case we finally decide to
allow each tracer to have their own trace buffer.

But now we are adding event tracing that writes to the current tracer's
buffer. This adds an interface to allow events to write to the current
tracer buffer without having to manage its own. Since event tracing
has no "tracer", and is just a way to hook into any other tracer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

Add the TRACE_SYSTEM sched for the sched events.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

Add the TRACE_SYSTEM irq for the irq events.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

This patch makes the event files, set_event and available_events
aware of the subsystem.

Now you can enable an entire subsystem with:

  echo 'irq:*' > set_event

Note: the '*' is not needed.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

If a trace point header defines TRACE_SYSTEM, then it will add the
following trace points into that event system.

If include/trace/irq_event_types.h has:

 #define TRACE_SYSTEM irq

at the top and

 #undef TRACE_SYSTEM

at the bottom, then a directory "irq" will be created in the
/debug/tracing/events directory. Inside that directory will contain the
two trace points that are defined in include/trace/irq_event_types.h.

Only adding the above to irq and not to sched, we get:

 # ls /debug/tracing/events/
irq                     sched_process_exit  sched_signal_send  sched_wakeup_new
sched_kthread_stop      sched_process_fork  sched_switch
sched_kthread_stop_ret  sched_process_free  sched_wait_task
sched_migrate_task      sched_process_wait  sched_wakeup

 # ls /debug/tracing/events/irq
irq_handler_entry  irq_handler_exit

If we add #define TRACE_SYSTEM sched to the trace/sched_event_types.h
then the rest of the trace events will be put in a sched directory
within the events directory.

I've been playing with this idea of the subsystem for a while, but
recently Tom Zanussi posted some patches to lkml that included this
method. Tom's approach was clean and got me to finally put some effort
to clean up the event trace points.

Thanks to Tom Zanussi for demonstrating how nice the subsystem
method is.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

Impact: clean up

To further facilitate the ease of adding trace points for developers, this
patch creates include/trace/trace_events.h and
include/trace/trace_event_types.h.

The former file will hold the trace/<type>.h files and the latter will hold
the trace/<type>_event_types.h files.

To create new tracepoints and to have them automatically
appear in the event tracer, a developer makes the trace/<type>.h file
which includes <linux/tracepoint.h> and the trace/<type>_event_types.h file.

The trace/<type>_event_types.h file will hold the TRACE_FORMAT
macros.

Then add the trace/<type>.h file to trace/trace_events.h,
and add the trace/<type>_event_types.h to the trace_event_types.h file.

No need to modify files elsewhere.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

Impact: clean up

kcalloc is a better approach to allocate a NULL array.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

Impact: clean up

Instead of listing the trace options like:

 # cat /debug/tracing/trace_options
print-parent nosym-offset nosym-addr noverbose noraw nohex nobin noblock nostacktrace nosched-tree ftrace_printk noftrace_preempt nobranch annotate nouserstacktrace nosym-userobj

We now list them like:

 # cat /debug/tracing/trace_options
print-parent
nosym-offset
nosym-addr
noverbose
noraw
nohex
nobin
noblock
nostacktrace
nosched-tree
ftrace_printk
noftrace_preempt
nobranch
annotate
nouserstacktrace
nosym-userobj
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

Impact: fix compile warning and clean up

When I first wrote __tracing_open, instead of passing the error
code via the ERR_PTR macros, I lazily used a separate parameter
to hold the return for errors.

When Frederic Weisbecker updated that function, he used the Linux
kernel ERR_PTR for the returns. This caused the parameter return
to possibly not be initialized on error. gcc correctly pointed this
out with a warning.

This patch converts the entire function to use the Linux kernel
ERR_PTR macro methods.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

Impact: fix to possible race conditions

There's some uses of current_tracer that is not protected by the
trace_types_lock. There is a small chance that a sysadmin changes
the tracer while the current_tracer is being referenced.

If the race is hit, it is unlikely to cause any harm since the
tracers are constant and are not freed. But some strang side
effects may occur.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

This patch adds the tracer dependent options dynamically to the
options directory when the tracer is activated. These options are
removed when the tracer is deactivated.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

This patch creates an options directory in the debugfs, that contains
the available tracing options. These files contain 1 or 0, where 1
is the option is enabled and 0 it is disabled.

Simply echoing in 1 will enable the option and 0 will disable it.
This patch only contains the core options, not the tracer options.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

Conflicts:
	kernel/sched_clock.c

If the TSC is constant and non-stop, also set it reliable.

(We will turn this off in DMI quirks for multi-chassis systems)

The performance number on a 16-way Nehalem system running
32 tasks that context-switch between each other is significant:

   sched_clock_stable=0		sched_clock_stable=1
   ....................         ....................
   22.456925 million/sec        24.306972 million/sec   [+8.2%]

lmbench's "lat_ctx -s 0 2" goes from 0.63 microseconds to
0.59 microseconds - a 6.7% increase in context-switching
performance.

Perfstat of 1 million pipe context switches between two tasks:

 Performance counter stats for './pipe-test-1m':

       [before]           [after]
   ............      ............
   37621.421089      36436.848378    task clock ticks     (msecs)

              0                 0    CPU migrations       (events)
        2000274           2000189    context switches     (events)
            194               193    pagefaults           (events)
     8433799643        8171016416    CPU cycles           (events) -3.21%
     8370133368        8180999694    instructions         (events) -2.31%
        4158565           3895941    cache references     (events) -6.74%
          44312             46264    cache misses         (events)

    2349.287976       2279.362465    wall-time            (msecs)  -3.06%

The speedup comes straight from the reduction in the instruction
count. sched_clock_cpu() got simpler and the whole workload thus
executes faster.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Allow CONFIG_HAVE_UNSTABLE_SCHED_CLOCK architectures to still specify
that their sched_clock() implementation is reliable.

This will be used by x86 to switch on a faster sched_clock_cpu()
implementation on certain CPU types.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: implement new tracing timestamp APIs

Add three trace clock variants, with differing scalability/precision
tradeoffs:

 -   local: CPU-local trace clock
 -  medium: scalable global clock with some jitter
 -  global: globally monotonic, serialized clock

Make the ring-buffer use the local trace clock internally.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

make sure we dont execute more complex sched_clock() code in NMI context.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: add new tracepoints

Add them to the generic IRQ code, that way every architecture
gets these new tracepoints, not just x86.

Using Steve's new 'TRACE_FORMAT', I can get function graph
trace as follows using the original two IRQ tracepoints:

 3)               |    handle_IRQ_event() {
 3)               |    /* (irq_handler_entry) irq=28 handler=eth0 */
 3)               |    e1000_intr_msi() {
 3)   2.460 us    |      __napi_schedule();
 3)   9.416 us    |    }
 3)               |    /* (irq_handler_exit) irq=28 handler=eth0 return=handled */
 3) + 22.935 us   |  }
Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: restructure the VFS layout of per CPU trace buffers

The per cpu trace files are all in a single directory:
/debug/tracing/per_cpu. In case of a large number of cpu, the
content of this directory becomes messy so we create now one
directory per cpu inside /debug/tracing/per_cpu which contain
each their own trace_pipe and trace files.

Ie:

 /debug/tracing$ ls -R per_cpu
 per_cpu:
 cpu0  cpu1

 per_cpu/cpu0:
 trace  trace_pipe

 per_cpu/cpu1:
 trace  trace_pipe
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Merge branch 'tip/tracing/ftrace' of ssh://master.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/ftrace

Peter Zijlstra warned that TPPROTO and TPARGS might become something
other than a simple copy of itself. To prevent this from having
side effects in the TRACE_FORMAT macro in tracepoint.h, we add a
PARAMS() macro to be defined as just a wrapper.
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

There's been a bit confusion to whether DEFINE/DECLARE_TRACE_FMT should
be a DEFINE or a DECLARE. Ingo Molnar suggested simply calling it
TRACE_FORMAT.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

Now that several per-cpu files can be read or spliced at the
same, we want the read/splice callbacks for tracing files to be
reentrants.

Until now, a single global mutex (trace_types_lock) serialized
the access to tracing_read_pipe(), tracing_splice_read_pipe(),
and the seq helpers.

Ie: it means that if a user tries to read trace_pipe0 and
trace_pipe1 at the same time, the access to the function
tracing_read_pipe() is contended and one reader must wait for
the other to finish its read call.

The trace_type_lock mutex is mostly here to serialize the access
to the global current tracer (current_trace), which can be
changed concurrently. Although the iter struct keeps a private
pointer to this tracer, its callbacks can be changed by another
function.

The method used here is to not keep anymore private reference to
the tracer inside the iterator but to make a copy of it inside
the iterator. Then it checks on subsequents read calls if the
tracer has changed. This is not costly because the current
tracer is not expected to be changed often, so we use a branch
prediction for that.

Moreover, we add a private mutex to the iterator (there is one
iterator per file descriptor) to serialize the accesses in case
of multiple consumers per file descriptor (which would be a
silly idea from the user). Note that this is not to protect the
ring buffer, since the ring buffer already serializes the
readers accesses. This is to prevent from traces weirdness in
case of concurrent consumers. But these mutexes can be dropped
anyway, that would not result in any crash. Just tell me what
you think about it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: split up tracing output per cpu

Currently, on the tracing debugfs directory, three files are
available to the user to let him extracting the trace output:

- trace is an iterator through the ring-buffer. It's a reader
  but not a consumer It doesn't block when no more traces are
  available.

- trace pretty similar to the former, except that it adds more
  informations such as prempt count, irq flag, ...

- trace_pipe is a reader and a consumer, it will also block
  waiting for traces if necessary (heh, yes it's a pipe).

The traces coming from different cpus are curretly mixed up
inside these files. Sometimes it messes up the informations,
sometimes it's useful, depending on what does the tracer
capture.

The tracing_cpumask file is useful to filter the output and
select only the traces captured a custom defined set of cpus.
But still it is not enough powerful to extract at the same time
one trace buffer per cpu.

So this patch creates a new directory: /debug/tracing/per_cpu/.

Inside this directory, you will now find one trace_pipe file and
one trace file per cpu.

Which means if you have two cpus, you will have:

 trace0
 trace1
 trace_pipe0
 trace_pipe1

And of course, reading these files will have the same effect
than with the usual tracing files, except that you will only see
the traces from the given cpu.

The original all-in-one cpu trace file are still available on
their original place.

Until now, only one consumer was allowed on trace_pipe to avoid
racy consuming on the ring-buffer. Now the approach changed a
bit, you can have only one consumer per cpu.

Which means you are allowed to read concurrently trace_pipe0 and
trace_pipe1 But you can't have two readers on trace_pipe0 or
trace_pipe1.

Following the same logic, if there is one reader on the common
trace_pipe, you can not have at the same time another reader on
trace_pipe0 or in trace_pipe1. Because in trace_pipe is already
a consumer in all cpu buffers in essence.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Merge branch 'tip/tracing/ftrace' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/ftrace

Impact: remove old debug/tracing API

/debug/tracing/latency_trace is an old legacy format we kept from
the old latency tracer. Remove the file for now. If there's any
useful bit missing then we'll propagate any useful output bits into
the /debug/tracing/trace output.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: fix CPU hotplug lockup

bts_hotcpu_handler() is called with irqs disabled, so using mutex_lock()
is a no-no.

All the BTS codepaths here are atomic (they do not schedule), so using
a spinlock is the right solution.

Cc: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

This patch adds the directory /debug/tracing/events/ that will contain
all the registered trace points.

 # ls /debug/tracing/events/
sched_kthread_stop      sched_process_fork  sched_switch
sched_kthread_stop_ret  sched_process_free  sched_wait_task
sched_migrate_task      sched_process_wait  sched_wakeup
sched_process_exit      sched_signal_send   sched_wakeup_new

 # ls /debug/tracing/events/sched_switch/
enable

 # cat /debug/tracing/events/sched_switch/enable
1

 # cat /debug/tracing/set_event
sched_switch
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

This patch changes the trace/sched.h to use the DECLARE_TRACE_FMT
such that they are automatically registered with the event tracer.

And it also adds the tracing sched headers to kernel/trace/events.c
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

This patch creates the event tracing infrastructure of ftrace.
It will create the files:

 /debug/tracing/available_events
 /debug/tracing/set_event

The available_events will list the trace points that have been
registered with the event tracer.

set_events will allow the user to enable or disable an event hook.

example:

 # echo sched_wakeup > /debug/tracing/set_event

Will enable the sched_wakeup event (if it is registered).

 # echo "!sched_wakeup" >> /debug/tracing/set_event

Will disable the sched_wakeup event (and only that event).

 # echo > /debug/tracing/set_event

Will disable all events (notice the '>')

 # cat /debug/tracing/available_events > /debug/tracing/set_event

Will enable all registered event hooks.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

This patch creates a DEFINE_TRACE_FMT to map to DECLARE_TRACE.
This allows for the developers to place format strings and
args in with their tracepoint declaration. A tracer may now
override the DEFINE_TRACE_FMT macro and use it to record
a default format.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

* 'proc-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/adobriyan/proc:
  proc: fix PG_locked reporting in /proc/kpageflags

* 'i2c-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6:
  Add i2c_board_info for RiscPC PCF8583
  i2c: Make sure i2c_algo_bit_data.timeout is HZ-independent
  i2c-dev: Clarify the unit of ioctl I2C_TIMEOUT
  i2c: Timeouts reach -1
  i2c: Fix misplaced parentheses

Merge branch 'firedtv-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6

* 'firedtv-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6:
  firedtv: dvb_frontend_info for FireDTV S2, fix "frequency limits undefined" error
  firedtv: massive refactoring
  firedtv: rename files, variables, functions from firesat to firedtv
  firedtv: Use DEFINE_SPINLOCK
  firedtv: fix registration - adapter number could only be zero
  firedtv: use length_field() of PMT as length
  firedtv: fix returned struct for ca_info
  firedtv: cleanups and minor fixes
  ieee1394: remove superfluous assertions
  ieee1394: inherit ud vendor_id from node vendor_id
  ieee1394: add hpsb_node_read() and hpsb_node_lock()
  ieee1394: use correct barrier types between accesses of nodeid and generation
  firesat: copyrights, rename to firedtv, API conversions, fix remote control input
  firesat: avc resend
  firesat: update isochronous interface, add CI support
  firesat: add DVB-S support for DVB-S2 devices
  firesat: fix DVB-S2 device recognition
  DVB: add firesat driver

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: Fix deadlock in ext4_write_begin() and ext4_da_write_begin()
  ext4: Add fallback for find_group_flex

Add the necessary i2c_board_info structure to fix the lack of PCF8583
RTC on RiscPC.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>

i2c_algo_bit_data.timeout is supposed to be in jiffies, so drivers
should use set this value in terms of HZ.

Ultimately I think this field should be discarded in favor of
i2c_adapter.timeout, but that's left for a future patch.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Lennert Buytenhek <kernel@wantstofly.org>
Acked-by: Len Sorensen <lsorense@csclub.uwaterloo.ca>

The unit in which user-space can set the bus timeout value is jiffies
for historical reasons (back when HZ was always 100.) This is however
not good because user-space doesn't know how long a jiffy lasts. The
timeout value should instead be set in a fixed time unit. Given the
original value of HZ, this unit should be 10 ms, for compatibility.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>

With a postfix decrement these timeouts reach -1 rather than 0, but
after the loop it is tested whether they have become 0.

As pointed out by Jean Delvare, the condition we are waiting for should
also be tested before the timeout. With the current order, you could
exit with a timeout error while the job is actually done.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>