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: Steven 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: Anton 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: Ingo 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: Frederic 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: Ingo Molnar <mingo@elte.hu>

Impact: add new debugfs API

With ftrace, some tracers are registered in early initcalls
and attempt to create files on the debugfs filesystem.
Depending on when they are activated, they can try to create their
file at any time. Some checks can be done on the tracing area
but providing a helper to know if debugfs is registered make it
really more easy.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237759847-21025-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo 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: Dmitri Vorobiev <dmitri.vorobiev@movial.com>
LKML-Reference: <1237741871-5827-4-git-send-email-dmitri.vorobiev@movial.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Merge branches 'tracing/ftrace', 'tracing/hw-breakpoints', 'tracing/ring-buffer', 'tracing/textedit' and 'linus' into tracing/core

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: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237694675-23509-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo 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: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237694675-23509-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo 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: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237606416-22268-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo 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: Stephen 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: Ingo Molnar <mingo@elte.hu>

Impact: new tracing infrastructure feature

Provide infrastructure to generate software perf counter events
from tracepoints.
Signed-off-by: Peter 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: Ingo 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: Peter 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: Ingo 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: Peter 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: 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

The libaio test harness turned up a problem whereby lookup_ioctx on a
bogus io context was returning the 1 valid io context from the list
(harness/cases/3.p).

Because of that, an extra put_iocontext was done, and when the process
exited, it hit a BUG_ON in the put_iocontext macro called from exit_aio
(since we expect a users count of 1 and instead get 0).

The problem was introduced by "aio: make the lookup_ioctx() lockless"
(commit abf137dd).

Thanks to Zach for pointing out that hlist_for_each_entry_rcu will not
return with a NULL tpos at the end of the loop, even if the entry was
not found.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Acked-by: Zach Brown <zach.brown@oracle.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Remove a source of fput() call from inside IRQ context.  Myself, like Eric,
wasn't able to reproduce an fput() call from IRQ context, but Jeff said he was
able to, with the attached test program.  Independently from this, the bug is
conceptually there, so we might be better off fixing it.  This patch adds an
optimization similar to the one we already do on ->ki_filp, on ->ki_eventfd.
Playing with ->f_count directly is not pretty in general, but the alternative
here would be to add a brand new delayed fput() infrastructure, that I'm not
sure is worth it.
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Zach Brown <zach.brown@oracle.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Sam Ravnborg says:
 "We have several architectures that plays strange games with $(CC) and
  $(CROSS_COMPILE).

  So we need to postpone any use of $(call cc-option..) until we have
  included the arch specific Makefile so we try with the correct $(CC)
  version."
Requested-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6:
  [S390] make page table upgrade work again
  [S390] make page table walking more robust
  [S390] Dont check for pfn_valid() in uaccess_pt.c
  [S390] ftrace/mcount: fix kernel stack backchain
  [S390] topology: define SD_MC_INIT to fix performance regression
  [S390] __div64_31 broken for CONFIG_MARCH_G5

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid:
  HID: fix waitqueue usage in hiddev
  HID: fix incorrect free in hiddev

* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
  Btrfs: Clear space_info full when adding new devices
  Btrfs: Fix locking around adding new space_info

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: Steven 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: Steven 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: Steven 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: Steven Rostedt <srostedt@redhat.com>

Nick Piggin noticed this (very unlikely) race between setting a page
dirty and creating the buffers for it - we need to hold the mapping
private_lock until we've set the page dirty bit in order to make sure
that create_empty_buffers() might not build up a set of buffers without
the dirty bits set when the page is dirty.

I doubt anybody has ever hit this race (and it didn't solve the issue
Nick was looking at), but as Nick says: "Still, it does appear to solve
a real race, which we should close."
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This makes sure that gcc doesn't try to optimize away wrapping
arithmetic, which the kernel occasionally uses for overflow testing, ie
things like

	if (ptr + offset < ptr)

which technically is undefined for non-unsigned types. See

	http://bugzilla.kernel.org/show_bug.cgi?id=12597

for details.

Not all versions of gcc support it, so we need to make it conditional
(it looks like it was introduced in gcc-3.4).
Reminded-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic 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: Ingo 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: Steven Rostedt <srostedt@redhat.com>

When I review the sensitive code ftrace_nmi_enter(), I found
the atomic variable nmi_running does protect NMI VS do_ftrace_mod_code(),
but it can not protects NMI(entered nmi) VS NMI(ftrace_nmi_enter()).

cpu#1                   | cpu#2                 | cpu#3
ftrace_nmi_enter()      | do_ftrace_mod_code()  |
  not modify            |                       |
------------------------|-----------------------|--
executing               | set mod_code_write = 1|
executing             --|-----------------------|--------------------
executing               |                       | ftrace_nmi_enter()
executing               |                       |    do modify
------------------------|-----------------------|-----------------
ftrace_nmi_exit()       |                       |

cpu#3 may be being modified the code which is still being executed on cpu#1,
it will have undefined results and possibly take a GPF, this patch
prevents it occurred.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <49C0B411.30003@cn.fujitsu.com>
Signed-off-by: Steven 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: Ingo 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: Jaswinder 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: Ingo Molnar <mingo@elte.hu>

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging-2.6:
  Staging: benet: remove driver now that it is merged in drivers/net/

* 'for-2.6.29' of git://linux-nfs.org/~bfields/linux:
  nfsd: nfsd should drop CAP_MKNOD for non-root
  NFSD: provide encode routine for OP_OPENATTR

The benet driver is now in the proper place in drivers/net/benet, so we
can remove the staging version.
Acked-by: Sathya Perla <sathyap@serverengines.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
  powerpc/ps3: ps3_defconfig updates
  powerpc/mm: Respect _PAGE_COHERENT on classic ppc32 SW
  powerpc/5200: Enable CPU_FTR_NEED_COHERENT for MPC52xx
  ps3/block: Replace mtd/ps3vram by block/ps3vram

* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
  module: fix refptr allocation and release order

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6:
  USB: storage: Unusual USB device Prolific 2507 variation added
  USB: Add device id for Option GTM380 to option driver
  USB: Add Vendor/Product ID for new CDMA U727 to option driver
  USB: Updated unusual-devs entry for USB mass storage on Nokia 6233
  USB: Option: let cdc-acm handle Sony Ericsson F3507g / Dell 5530
  USB: EHCI: expedite unlinks when the root hub is suspended
  USB: EHCI: Fix isochronous URB leak
  USB: option.c: add ZTE 622 modem device
  USB: wusbcore/wa-xfer, fix lock imbalance
  USB: misc/vstusb, fix lock imbalance
  USB: misc/adutux, fix lock imbalance
  USB: image/mdc800, fix lock imbalance
  USB: atm/cxacru, fix lock imbalance
  USB: unusual_devs: Add support for GI 0431 SD-Card interface
  USB: serial: new cp2101 device id
  USB: serial: ftdi: enable UART detection on gnICE JTAG adaptors blacklist interface0
  USB: serial: add FTDI USB/Serial converter devices
  USB: usbfs: keep async URBs until the device file is closed
  USB: usbtmc: add protocol 1 support
  USB: usbtmc: fix stupid bug in open()

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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
  ALSA: Fix vunmap and free order in snd_free_sgbuf_pages()
  ALSA: mixart, fix lock imbalance
  ALSA: pcm_oss, fix locking typo
  ALSA: oss-mixer - Fixes recording gain control
  ALSA: hda - Workaround for buggy DMA position on ATI controllers
  ALSA: hda - Fix DMA mask for ATI controllers
  ALSA: opl3sa2 - Fix NULL dereference when suspending snd_opl3sa2