Impact: clean up

Now that ftrace_lock is a mutex, there is no reason to have three
different mutexes protecting similar data. All the mutex paths
are not in hot paths, so having a mutex to cover more data is
not a problem.

This patch removes the ftrace_sysctl_lock and ftrace_start_lock
and uses the ftrace_lock to protect the locations that were protected
by these locks. By doing so, this change also removes some of
the lock nesting that was taking place.

There are still more mutexes in ftrace.c that can probably be
consolidated, but they can be dealt with later. We need to be careful
about the way the locks are nested, and by consolidating, we can cause
a recursive deadlock.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: clean up

The older versions of ftrace required doing the ftrace list
search under atomic context. Now all the calls are in non-atomic
context. There is no reason to keep the ftrace_lock as a spinlock.

This patch converts it to a mutex.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Allow for other tracers to add their own commands for function
selection. This interface gives a trace the ability to name a
command for function selection. Right now it is pretty limited
in what it offers, but this is a building step for more features.

The :mod: command is converted to this interface and also serves
as a template for other implementations.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: fix to prevent empty set_ftrace_filter and no ftrace output

The function filter is used to only trace a given set of functions.
The filter is enabled when a function name is echoed into the
set_ftrace_filter file. But if the name has a typo and the function
is not found, the filter is enabled, but no function is listed.

This makes a confusing situation where set_ftrace_filter is empty
but no functions ever get enabled for tracing.

For example:

 # cat /debug/tracing/set_ftrace_filter

  #### all functions enabled ####

 # echo bad_name > set_ftrace_filter
 # cat /debug/tracing/set_ftrace_filter

 # echo function > current_tracer
 # cat trace

  # tracer: nop
  #
  #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
  #              | |       |          |         |

This patch changes that to only enable filtering if a function
is set to be filtered on. Now, the filter is not enabled if
a bad name is echoed into set_ftrace_filter.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

This patch adds a "command" syntax to the function filtering files:

  /debugfs/tracing/set_ftrace_filter
  /debugfs/tracing/set_ftrace_notrace

Of the format:  <function>:<command>:<parameter>

The command is optional, and dependent on the command, so are
the parameters.

 echo do_fork > set_ftrace_filter

Will only trace 'do_fork'.

 echo 'sched_*' > set_ftrace_filter

Will only trace functions starting with the letters 'sched_'.

 echo '*:mod:ext3' > set_ftrace_filter

Will trace only the ext3 module functions.

 echo '*write*:mod:ext3' > set_ftrace_notrace

Will prevent the ext3 functions with the letters 'write' in
the name from being traced.

 echo '!*_allocate:mod:ext3' > set_ftrace_filter

Will remove the functions in ext3 that end with the letters
'_allocate' from the ftrace filter.

Although this patch implements the 'command' format, only the
'mod' command is supported. More commands to follow.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: clean up

ftrace_match_records does a lot of things that other features
can use. This patch breaks up ftrace_match_records and pulls
out ftrace_setup_glob and ftrace_match_record.

ftrace_setup_glob prepares a simple glob expression for use with
ftrace_match_record. ftrace_match_record compares a single record
with a glob type.

Breaking this up will allow for more features to run on individual
records.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: clean up

ftrace_match is too generic of a name. What it really does is
search all records and matches the records with the given string,
and either sets or unsets the functions to be traced depending
on if the parameter 'enable' is set or not.

This allows us to make another function called ftrace_match that
can be used to test a single record.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: clean up

To iterate over all the functions that dynamic trace knows about
it requires two for loops. One to iterate over the pages and the
other to iterate over the records within the page.

There are several duplications of these loops in ftrace.c. This
patch creates the macros do_for_each_ftrace_rec and
while_for_each_ftrace_rec to handle this logic, and removes the
duplicate code.

While making this change, I also discovered and fixed a small
bug that one of the iterations should exit the loop after it found the
record it was searching for. This used a break when it should have
used a goto, since there were two loops it needed to break out
from.  No real harm was done by this bug since it would only continue
to search the other records, and the code was in a slow path anyway.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: clean up, make set_ftrace_filter less confusing

The set_ftrace_filter shows only the functions that will be traced.
But when it is empty, it will trace all functions. This can be a bit
confusing.

This patch makes set_ftrace_filter show:

  #### all functions enabled ####

When all functions will be traced, and we do not filter only a select
few.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: clean up

While reviewing the ring buffer code, I thougth I saw a bug with

	if (!__raw_spin_trylock(&cpu_buffer->lock))
		goto out_unlock;

But I forgot that we use a variable "lock_taken" that is set if
the spinlock is taken, and only unlock it if that variable is set.

To avoid further confusion from other reviewers, this patch
renames the label out_unlock with out_reset, which is the more
appropriate name.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

I enabled all cgroup subsystems when compiling kernel, and then:
 # mount -t cgroup -o net_cls xxx /mnt
 # mkdir /mnt/0

This showed up immediately:
 BUG: MAX_LOCKDEP_SUBCLASSES too low!
 turning off the locking correctness validator.

It's caused by the cgroup hierarchy lock:
	for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
		struct cgroup_subsys *ss = subsys[i];
		if (ss->root == root)
			mutex_lock_nested(&ss->hierarchy_mutex, i);
	}

Now we have 9 cgroup subsystems, and the above 'i' for net_cls is 8, but
MAX_LOCKDEP_SUBCLASSES is 8.

This patch uses different lockdep keys for different subsystems.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NPaul Menage <menage@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We need to pass an unsigned long as the minimum, because it gets casted
to an unsigned long in the sysctl handler. If we pass an int, we'll
access four more bytes on 64bit arches, resulting in a random minimum
value.

[rientjes@google.com: fix type of `old_bytes']
Signed-off-by: NSven Wegener <sven.wegener@stealer.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Intel reported a 10% regression (mysql+sysbench) on a 16-way machine
with these patches:

  1596e297: sched: symmetric sync vs avg_overlap
  d942fb6c: sched: fix sync wakeups

Revert them.
Reported-by: N"Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Bisected-by: NLin Ming <ming.m.lin@intel.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The POSIX timer interface allows for absolute time expiry values through the
TIMER_ABSTIME flag, therefore we have to synchronize the timer to the clock
every time we start it.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

To decrease the chance of a missed enable, always enable the timer when we
sample it, we'll always disable it when we find that there are no active timers
in the jiffy tick.

This fixes a flood of warnings reported by Mike Galbraith.
Reported-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

While fixing some bugs in pahole (built-in.o files were not being
processed due to relocation problems) I found out about these packable
structures:

$ pahole --packable kernel/trace/ring_buffer.o  | grep ring
ring_buffer	72	64	8
ring_buffer_per_cpu	112	104	8

If we take a look at the current layout of struct ring_buffer we can see
that we have two 4 bytes holes.

$ pahole -C ring_buffer kernel/trace/ring_buffer.o
struct ring_buffer {
	unsigned int               pages;           /*     0     4 */
	unsigned int               flags;           /*     4     4 */
	int                        cpus;            /*     8     4 */

	/* XXX 4 bytes hole, try to pack */

	cpumask_var_t              cpumask;         /*    16     8 */
	atomic_t                   record_disabled; /*    24     4 */

	/* XXX 4 bytes hole, try to pack */

	struct mutex               mutex;           /*    32    32 */
	/* --- cacheline 1 boundary (64 bytes) --- */
	struct ring_buffer_per_cpu * * buffers;     /*    64     8 */

	/* size: 72, cachelines: 2, members: 7 */
	/* sum members: 64, holes: 2, sum holes: 8 */
	/* last cacheline: 8 bytes */
};

So, if I ask pahole to reorganize it:

$ pahole -C ring_buffer --reorganize kernel/trace/ring_buffer.o

struct ring_buffer {
	unsigned int               pages;           /*     0     4 */
	unsigned int               flags;           /*     4     4 */
	int                        cpus;            /*     8     4 */
	atomic_t                   record_disabled; /*    12     4 */
	cpumask_var_t              cpumask;         /*    16     8 */
	struct mutex               mutex;           /*    24    32 */
	struct ring_buffer_per_cpu * * buffers;     /*    56     8 */
	/* --- cacheline 1 boundary (64 bytes) --- */

	/* size: 64, cachelines: 1, members: 7 */
};   /* saved 8 bytes and 1 cacheline! */

We get it using just one 64 bytes cacheline.

To see what it did:

$ pahole -C ring_buffer --reorganize --show_reorg_steps \
	kernel/trace/ring_buffer.o | grep \/
/* Moving 'record_disabled' from after 'cpumask' to after 'cpus' */
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add the missing pair tracing_{start,stop}_record_cmdline() to record well
the cmdline associated with pid.

Changes in v2:

- fix a build error, the sched_switch tracer is needed to record the
  cmdline.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

I noticed by pure accident we have ptrace_fork() and friends. This was
added by "x86, bts: add fork and exit handling", commit
bf53de90.

I can't test this, ds_request_bts() returns -EOPNOTSUPP, but I strongly
believe this needs the fix. I think something like this program

	int main(void)
	{
		int pid = fork();

		if (!pid) {
			ptrace(PTRACE_TRACEME, 0, NULL, NULL);
			kill(getpid(), SIGSTOP);
			fork();
		} else {
			struct ptrace_bts_config bts = {
				.flags = PTRACE_BTS_O_ALLOC,
				.size  = 4 * 4096,
			};

			wait(NULL);

			ptrace(PTRACE_SETOPTIONS, pid, NULL, PTRACE_O_TRACEFORK);
			ptrace(PTRACE_BTS_CONFIG, pid, &bts, sizeof(bts));
			ptrace(PTRACE_CONT, pid, NULL, NULL);

			sleep(1);
		}

		return 0;
	}

should crash the kernel.

If the task is traced by its natural parent ptrace_reparented() returns 0
but we should clear ->btsxxx anyway.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NMarkus Metzger <markus.t.metzger@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Fix this sparse warning:

  kernel/trace/trace.c:458:9: warning: context imbalance in 'register_tracer' - unexpected unlock
Signed-off-by: NHannes Eder <hannes@hanneseder.net>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Fix these sparse warnings:

  kernel/trace/ring_buffer.c:70:37: warning: incorrect type in argument 2 (different signedness)
  kernel/trace/ring_buffer.c:84:39: warning: incorrect type in argument 2 (different signedness)
  kernel/trace/ring_buffer.c:96:43: warning: incorrect type in argument 2 (different signedness)
  kernel/trace/ring_buffer.c:2475:13: warning: incorrect type in argument 2 (different signedness)
  kernel/trace/ring_buffer.c:2475:13: warning: incorrect type in argument 2 (different signedness)
  kernel/trace/ring_buffer.c:2478:42: warning: incorrect type in argument 2 (different signedness)
  kernel/trace/ring_buffer.c:2478:42: warning: incorrect type in argument 2 (different signedness)
  kernel/trace/ring_buffer.c:2500:40: warning: incorrect type in argument 3 (different signedness)
  kernel/trace/ring_buffer.c:2505:44: warning: incorrect type in argument 2 (different signedness)
  kernel/trace/ring_buffer.c:2507:46: warning: incorrect type in argument 2 (different signedness)
  kernel/trace/trace.c:2130:40: warning: incorrect type in argument 3 (different signedness)
  kernel/trace/trace.c:2280:40: warning: incorrect type in argument 3 (different signedness)
Signed-off-by: NHannes Eder <hannes@hanneseder.net>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: make global variables and a global function static

The function '__trace_userstack' does not seem to have a caller, so it
is commented out.

Fix this sparse warnings:
  kernel/trace/trace.c:82:5: warning: symbol 'tracing_disabled' was not declared. Should it be static?
  kernel/trace/trace.c:600:10: warning: symbol 'trace_record_cmdline_disabled' was not declared. Should it be static?
  kernel/trace/trace.c:957:6: warning: symbol '__trace_userstack' was not declared. Should it be static?
  kernel/trace/trace.c:1694:5: warning: symbol 'tracing_release' was not declared. Should it be static?
Signed-off-by: NHannes Eder <hannes@hanneseder.net>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: clean up.

Fix typos in the comments.
Signed-off-by: NWenji Huang <wenji.huang@oracle.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

This patch is to make the function return early on failure, and give
correct return value on success.
Signed-off-by: NWenji Huang <wenji.huang@oracle.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: clean up.

Remove the unnecessary variable ret.
Signed-off-by: NWenji Huang <wenji.huang@oracle.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

The C99 specification states in section 6.11.5:

The placement of a storage-class specifier other than at the beginning
of the declaration specifiers in a declaration is an obsolescent
feature.
Signed-off-by: NTobias Klauser <tklauser@distanz.ch>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: change API and init bpage when copy

ring_buffer_read_page()/rb_remove_entries() may be called for
a partially consumed page.

Add a parameter for rb_remove_entries() and make it update
cpu_buffer->entries correctly for partially consumed pages.

ring_buffer_read_page() now returns the offset to the next event.

Init the bpage's time_stamp when return value is 0.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: Fix bug

I found several very very curious line.
It's so curious that it may be brought by typing mistake.

When (cpu_buffer->reader_page == cpu_buffer->commit_page):

1) We haven't copied it for bpage is changed:
   bpage = cpu_buffer->reader_page->page;
   memcpy(bpage->data, cpu_buffer->reader_page->page->data + read ... )
2) We need update cpu_buffer->reader_page->read, but
   "cpu_buffer->reader_page += read;" is not right.

[
  This bug was a typo. The commit->reader_page is a page pointer
  and not an index into the page. The line should have been
  commit->reader_page->read += read.  The other changes
  by Lai are nice clean ups to the code.  - SDR
]
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Impact: fix broken /proc/profile on UP machines

Commit c309b917 "cpumask: convert
kernel/profile.c" broke profiling.  prof_cpu_mask was previously
initialized to CPU_MASK_ALL, but left uninitialized in that commit.
We need to copy cpu_possible_mask (cpu_online_mask is not enough).
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Ingo Molnar suggested a series of clean ups for the splice code.
This patch implements those suggestions.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

This moves the pipe waiting code from tracing_read_pipe() into
tracing_wait_pipe(), which is useful to implement other fops, like
splice_read.
Signed-off-by: NEduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

Added and implemented tracing_pipe_fops->splice_read(). This allows
userspace programs to get tracing data more efficiently.
Signed-off-by: NEduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>

When one cats the trace file, the leaf functions are printed without brackets:

 function();

whereas in the trace_pipe file we'll see the following:

 function() {
 }

This is because the ring_buffer handling is not the same between those two files.
On the trace file, when an entry is printed, the iterator advanced and then we can
check the next entry.

There is no iterator with trace_pipe, the current entry to print has been peeked
and not consumed. So checking the next entry will still return the current one while
we don't consume it.

This patch introduces a new value for the output callbacks to ask the tracing
core to not consume the current entry after printing it.

We need it because we will have to consume the current entry ourself to check
the next one.

Now the trace_pipe is able to handle well the leaf functions.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: build fix

The BLK_DEV_IO_TRACE entry used to be in block/Kconfig - which
file itself was dependent on CONFIG_BLOCK. But now the entry is
in kernel/trace/Kconfig - which is present even on !CONFIG_BLOCK.

So add a 'depends on BLOCK' to BLK_DEV_IO_TRACE.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: simplification

Instead of requiring that plugins have the sequence:

  my_tracer_stop(my_trace_array);
  unregister_tracer(my_tracer);

it should be possible just do a:

  unregister_tracer(my_tracer);
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When the function graph tracer picks a return address, it ensures this address
is really a kernel text one by calling __kernel_text_address()

Actually this path has never been taken.Its role was more likely to debug the tracer
on the beginning of its development but this function is wasteful since it is called
for every traced function.

The fault check is already sufficient.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Move the power tracer headers to trace/power.h to keep ftrace.h and power bits
more easy to maintain as separated topics.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Making it more easy to do a basic regression test for this tracer.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup

Move blktrace.c to kernel/trace, also move its config entry.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: NJens Axboe <jens.axboe@oracle.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

list.h provides a dedicated primitive for
"list_del followed by list_add_tail"... list_move_tail.
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NStefan Richter <stefanr@s5r6.in-berlin.de>

Rename the async_*_special() functions to async_*_domain(), which
describes the purpose of these functions much better.
[Broke up long lines to silence checkpatch]
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>