Consecutive seq_puts calls with literal strings can be merged to a
single call. This reduces the size of the generated code, and can also
lead to slight .rodata reduction (because of fewer nul and padding
bytes). It should also shave a off a few clock cycles.

Link: http://lkml.kernel.org/r/1415479332-25944-3-git-send-email-linux@rasmusvillemoes.dkSigned-off-by: NRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Using seq_printf to print a simple string or a single character is a
lot more expensive than it needs to be, since seq_puts and seq_putc
exist.

These patches do

  seq_printf(m, s) -> seq_puts(m, s)
  seq_printf(m, "%s", s) -> seq_puts(m, s)
  seq_printf(m, "%c", c) -> seq_putc(m, c)

Subsequent patches will simplify further.

Link: http://lkml.kernel.org/r/1415479332-25944-2-git-send-email-linux@rasmusvillemoes.dkSigned-off-by: NRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

According to the documentation, adding "traceoff_on_warning" to the boot
command line should be enough to enable the feature. But right now it is
necessary to specify "traceoff_on_warning=". Along with fixing that, also
verify if the value passed, if any, is either "0" or "off".

Link: http://lkml.kernel.org/r/20141112231400.GL12281@uudg.orgSigned-off-by: NLuis Claudio R. Goncalves <lgoncalv@redhat.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Expose the new NMI safe accessor to clock monotonic to the tracer.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

The "uptime" trace clock added in:

    commit 8aacf017
    tracing: Add "uptime" trace clock that uses jiffies

has wraparound problems when the system has been up more
than 1 hour 11 minutes and 34 seconds. It converts jiffies
to nanoseconds using:
        (u64)jiffies_to_usecs(jiffy) * 1000ULL
but since jiffies_to_usecs() only returns a 32-bit value, it
truncates at 2^32 microseconds.  An additional problem on 32-bit
systems is that the argument is "unsigned long", so fixing the
return value only helps until 2^32 jiffies (49.7 days on a HZ=1000
system).

Avoid these problems by using jiffies_64 as our basis, and
not converting to nanoseconds (we do convert to clock_t because
user facing API must not be dependent on internal kernel
HZ values).

Link: http://lkml.kernel.org/p/99d63c5bfe9b320a3b428d773825a37095bf6a51.1405708254.git.tony.luck@intel.com

Cc: stable@vger.kernel.org # 3.10+
Fixes: 8aacf017 "tracing: Add "uptime" trace clock that uses jiffies"
Signed-off-by: NTony Luck <tony.luck@intel.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Currently, tracing_thresh works only if we specify it before selecting
function_graph tracer. If we do the opposite, tracing_thresh will change
it's value, but it will not be applied.
To fix it, we add update_thresh callback which is called whenever
tracing_thresh is updated and for function_graph tracer we register
handler which reinitializes tracer depending on tracing_thresh.

Link: http://lkml.kernel.org/p/20140718111727.GA3206@stfomichev-desktop.yandex.netSigned-off-by: NStanislav Fomichev <stfomichev@yandex-team.ru>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

The TRACE_ITER_PRINTK check in __trace_puts/__trace_bputs is missing,
so add it, to be consistent with __trace_printk/__trace_bprintk.
Those functions are all called by the same function: trace_printk().

Link: http://lkml.kernel.org/p/51E7A7D6.8090900@huawei.com

Cc: stable@vger.kernel.org # 3.11+
Signed-off-by: Nzhangwei(Jovi) <jovi.zhangwei@huawei.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Currently trace option stacktrace is not applicable for
trace_printk with constant string argument, the reason is
in __trace_puts/__trace_bputs ftrace_trace_stack is missing.

In contrast, when using trace_printk with non constant string
argument(will call into __trace_printk/__trace_bprintk), then
trace option stacktrace is workable, this inconstant result
will confuses users a lot.

Link: http://lkml.kernel.org/p/51E7A7C9.9040401@huawei.com

Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Nzhangwei(Jovi) <jovi.zhangwei@huawei.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Disabling reading and writing to the trace file should not be able to
disable all function tracing callbacks. There's other users today
(like kprobes and perf). Reading a trace file should not stop those
from happening.

Cc: stable@vger.kernel.org # 3.0+
Reviewed-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

It was missing the description of set_graph_notrace file.  Add it.

Link: http://lkml.kernel.org/p/1402590233-22321-5-git-send-email-namhyung@kernel.orgSigned-off-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

This fixes checkpatch warning:

"WARNING: debugfs_remove(NULL) is safe this check is probably not required"
Link: http://lkml.kernel.org/p/1403802871-8599-1-git-send-email-fabf@skynet.beSigned-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

The trace_seq_*() functions are a nice utility that allows users to manipulate
buffers with printf() like formats. It has its own trace_seq.h header in
include/linux and should be in its own file. Being tied with trace_output.c
is rather awkward.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

The freeing of an instance, if max data is configured, there will be
per cpu data structures created. But these are not freed when the instance
is deleted, which causes a memory leak.

A new helper function is added that frees the individual buffers within a
trace array, instead of duplicating the code. This way changes made for one
are applied to the other (normal buffer vs max buffer).

Link: http://lkml.kernel.org/r/87k38pbake.fsf@sejong.aot.lge.comReported-by: NNamhyung Kim <namhyung@gmail.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

The recent addition of saved_cmdlines_size file had some remaining
(minor - mostly coding style) issues.  Fix them by passing pointer
name to sizeof() and using scnprintf().

Link: http://lkml.kernel.org/p/1402384295-23680-1-git-send-email-namhyung@kernel.org

Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

The per_cpu buffers are created one per possible CPU. But these do
not mean that those CPUs are online, nor do they even exist.

With the addition of the ring buffer polling, it assumes that the
caller polls on an existing buffer. But this is not the case if
the user reads trace_pipe from a CPU that does not exist, and this
causes the kernel to crash.

Simple fix is to check the cpu against buffer bitmask against to see
if the buffer was allocated or not and return -ENODEV if it is
not.

More updates were done to pass the -ENODEV back up to userspace.

Link: http://lkml.kernel.org/r/5393DB61.6060707@oracle.comReported-by: NSasha Levin <sasha.levin@oracle.com>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

When an instance is created, it also gets a snapshot ring buffer
allocated (with minimum of pages). But when it is deleted the snapshot
buffer is not. There was a helper function added to match the allocation
of these ring buffers to a way to free them, but it wasn't used by
the deletion of an instance. Using that helper function solves this
memory leak.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Yoshihiro Yunomae reported that the ring buffer data for a trace
instance does not get properly cleaned up when it fails. He proposed
a patch that manually cleaned the data up and addad a bunch of labels.
The labels are not needed because all trace array is allocated with
a kzalloc which initializes it to 0 and all kfree()s can take a NULL
pointer and will ignore it.

Adding a new helper function free_trace_buffers() that can also take
null buffers to free the buffers that were allocated by
allocate_trace_buffers().

Link: http://lkml.kernel.org/r/20140605223522.32311.31664.stgit@yunodevelReported-by: NYoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Introduce saved_cmdlines_size file for changing the number of saved pid-comms.
saved_cmdlines currently stores 128 command names using SAVED_CMDLINES, but
'no-existing processes' names are often lost in saved_cmdlines when we
read the trace data. So, by introducing saved_cmdlines_size file, we can
now change the 128 command names saved to something much larger if needed.

When we write a value to saved_cmdlines_size, the number of the value will
be stored in pid-comm list:

	# echo 1024 > /sys/kernel/debug/tracing/saved_cmdlines_size

Here, 1024 command names can be stored. The default number is 128 and the maximum
number is PID_MAX_DEFAULT (=32768 if CONFIG_BASE_SMALL is not set). So, if we
want to avoid losing any command names, we need to set 32768 to
saved_cmdlines_size.

We can read the maximum number of the list:

	# cat /sys/kernel/debug/tracing/saved_cmdlines_size
	128

Link: http://lkml.kernel.org/p/20140605012427.22115.16173.stgit@yunodevelSigned-off-by: NYoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

If allocation of the max_buffer fails on boot up, the error path will
free both per_cpu data structures from the buffers. With the new redesign
of the code, those structures are freed if allocations failed. That is,
the helper function that allocates the buffers will free the per cpu data
on failure. No need to do it again. In fact, the second free will cause
a bug as the code can not handle a double free.

Link: http://lkml.kernel.org/p/20140603042803.27308.30956.stgit@yunodevelSigned-off-by: NYoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

With the conversion of the saved_cmdlines output to use seq_read, there
is now a race between accessing the values of the saved_cmdlines and
the writing to them. The trace_cmdline_lock needs to be taken at
the start and stop of the seq calls.

A new __trace_find_cmdline() call is created to allow for the look up
to happen without taking the lock.

Fixes: 42584c81 tracing: Have saved_cmdlines use the seq_read infrastructure
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

In order to prevent the saved cmdline cache from being filled when
tracing is not active, the comms are only recorded after a trace event
is recorded.

The problem is, a comm can fail to be recorded if the trace_cmdline_lock
is held. That lock is taken via a trylock to allow it to happen from
any context (including NMI). If the lock fails to be taken, the comm
is skipped. No big deal, as we will try again later.

But! Because of the code that was added to only record after an event,
we may not try again later as the recording is made as a oneshot per
event per CPU.

Only disable the recording of the comm if the comm is actually recorded.

Fixes: 7ffbd48d "tracing: Cache comms only after an event occurred"
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Current tracing_saved_cmdlines_read() implementation is naive; It allocates
a large buffer, constructs output data to that buffer for each read
operation, and then copies a portion of the buffer to the user space
buffer. This has several issues such as slow memory allocation, high
CPU usage, and even corruption of the output data.

The seq_read infrastructure is made to handle this type of work.
By converting it to use seq_read() the code becomes smaller, simplified,
as well as correct.

Link: http://lkml.kernel.org/p/20140220084431.3839.51793.stgit@yunodevelSigned-off-by: NHidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: NYoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

trace_printk() is used to debug fast paths within the kernel. Places
that gets called in any context (interrupt or NMI) or thousands of
times a second. Something you do not want to do with a printk().

In order to make it completely lockless as it needs a temporary buffer
to handle some of the string formatting, a page is created per cpu for
every context (four per cpu; normal, softirq, irq, NMI).

Since trace_printk() should only be used for debugging purposes,
there's no reason to waste memory on these buffers on a production
system. That means, trace_printk() should never be used unless a
developer is debugging their kernel. There's macro magic to allocate
the buffers if trace_printk() is used anywhere in the kernel.

To help enforce that trace_printk() isn't used outside of development,
when it is used, a nasty banner is displayed on bootup (or when a module
is loaded that uses trace_printk() and the kernel core does not).

Here's the banner:

 **********************************************************
 **   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **
 **                                                      **
 ** trace_printk() being used. Allocating extra memory.  **
 **                                                      **
 ** This means that this is a DEBUG kernel and it is     **
 ** unsafe for produciton use.                           **
 **                                                      **
 ** If you see this message and you are not debugging    **
 ** the kernel, report this immediately to your vendor!  **
 **                                                      **
 **   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **
 **********************************************************

That should hopefully keep developers from trying to sneak in a
trace_printk() or two.

Link: http://lkml.kernel.org/p/20140528131440.2283213c@gandalf.local.homeSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

Replace uses of &__get_cpu_var for address calculation with this_cpu_ptr.

Link: http://lkml.kernel.org/p/alpine.DEB.2.10.1404291415560.18364@gentwo.orgAcked-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Now that the ring buffer has a built in way to wake up readers
when there's data, using irq_work such that it is safe to do it
in any context. But it was still using the old "poor man's"
wait polling that checks every 1/10 of a second to see if it
should wake up a waiter. This makes the latency for a wake up
excruciatingly long. No need to do that anymore.

Completely remove the different wait_poll types from the tracers
and have them all use the default one now.
Reported-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

When reading from trace_pipe, if tracing is off but nothing was read
it should block. If something is read and tracing is off, then EOF
is returned. If tracing is on and there's nothing to read, it will block.

But because the check of whether tracing is off and something was read
is done after the block on the pipe, it is hit or miss if the EOF is
returned or not leading to inconsistent behavior.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

This patch adds static to the following functions:
-cycle_t buffer_ftrace_now
-void free_snapshot
-int trace_selftest_startup_dynamic_tracing

Link: http://lkml.kernel.org/p/20140417214442.d7abc7c0b0e4b90e7fedecc9@skynet.beSigned-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

In preparation for having tracers enabled in instances, the max_lock
should be unique as updating the max for one tracer is a separate
operation than updating it for another tracer using a different max.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

In preparation for letting the latency tracers be used by instances,
remove the global tracing_max_latency variable and add a max_latency
field to the trace_array that the latency tracers will now use.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Instead of having a list of global functions that are called,
as only one global function is allow to be enabled at a time, there's
no reason to have a list.

Instead, simply have all the users of the global ops, use the global ops
directly, instead of registering their own ftrace_ops. Just switch what
function is used before enabling the function tracer.

This removes a lot of code as well as the complexity involved with it.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

that commit has fixed only the parts of that mess in fs/splice.c itself;
there had been more in several other ->splice_read() instances...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The debugfs tracing README file lists all the function triggers except for
dump and cpudump. These should be added too.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

all pipe_buffer_operations have the same instances of those...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

While working on my tutorial for 2014 Linux Collaboration Summit
I found that the traceon trigger did not work when conditions were
used. The other triggers worked fine though. Looking into it, it
is because of the way the triggers use the ring buffer to store
the fields it will use for the condition. But if tracing is off, nothing
is stored in the buffer, and the tracepoint exits before calling the
trigger to test the condition. This is fine for all the triggers that
only work when tracing is on, but for traceon trigger that is to
work when tracing is off, nothing happens.

The fix is simple, just use a temp ring buffer to record the event
if tracing is off and the event has a trace event conditional trigger
enabled. The rest of the tracepoint code will work just fine, but
the tracepoint wont be recorded in the other buffers.

Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Being able to change the trace clock at boot can be advantageous if
you need a better source of when things happen across CPUs. The default
trace clock is the fastest, but it uses local clocks which may not be
synced across CPUs and it does not let you know when events took place
with respect to events on other CPUs.

The global trace clock can help in this case, and if you do not care
about timings, the counter "clock" is the best, as that is just a  simple
atomic counter that is incremented for every event.

Usage is to add "trace_clock=counter" on the kernel command line. You
can replace counter with "global" or any of the clocks listed in
/sys/kernel/debug/tracing/trace_clock
Suggested-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Appreciated-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Create a "set_ftrace_filter" and "set_ftrace_notrace" files in the instance
directories to let users filter of functions to trace for the given instance.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

As tracers will soon be used by instances, the tracer enabled field
needs to be converted to a counter instead of a boolean.
This counter is protected by the trace_types_lock mutex.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

When an instance is about to be deleted, make sure the tracer
is set to nop. If it isn't reset the tracer and set it to the nop
tracer, otherwise memory leaks and bad pointers may result.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Currently, only the top level instance can have tracing options.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Currently the tracers (function, function_graph, irqsoff, etc) can only
be used by the top level tracing directory (not for instances).

This sets up the infrastructure to allow instances to be able to
run a separate tracer apart from the what the top level tracing is
doing.

As tracers need to adapt for being used by instances, the tracers
must flag if they can be used by instances or not. Currently only the
'nop' tracer can be used by all instances.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>