Impact: let modules add trace events

The trace event code requires some functions to be exported to allow
modules to use TRACE_EVENT. This patch adds EXPORT_SYMBOL_GPL to the
necessary functions.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Impact: makes it possible to define events in modules

The events are created by reading down the section that they are linked
in by the macros. But this is not scalable to modules. This patch converts
the manipulations to use a global link list, and on boot up it adds
the items in the section to the list.

This change will allow modules to add their tracing events to the list as
well.

Note, this change alone does not permit modules to use the TRACE_EVENT macros,
but the change is needed for them to eventually do so.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

This patch moves the ftrace creation into include/trace/ftrace.h and
simplifies the work of developers in adding new tracepoints.
Just the act of creating the trace points in include/trace and including
define_trace.h will create the events in the debugfs/tracing/events
directory.

This patch removes the need of include/trace/trace_events.h
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

In preparation to allowing trace events to happen in modules, we need
to move some of the local declarations in the kernel/trace directory
into include/linux.

This patch simply moves the declarations and performs no context changes.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

In the process to make TRACE_EVENT macro work for modules, the trace_seq
operations must be available for core kernel code.

These operations are quite useful and can be used for other implementations.

The main idea is that we create a trace_seq handle that acts very much
like the seq_file handle.

	struct trace_seq *s = kmalloc(sizeof(*s, GFP_KERNEL);

	trace_seq_init(s);
	trace_seq_printf(s, "some data %d\n", variable);

	printk("%s", s->buffer);

The main use is to allow a top level function call several other functions
that may store printf like data into the buffer. Then at the end, the top
level function can process all the data with any method it would like to.
It could be passed to userspace, output via printk or even use seq_file:

	trace_seq_to_user(s, ubuf, cnt);
	seq_puts(m, s->buffer);
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

This patch lowers the number of places a developer must modify to add
new tracepoints. The current method to add a new tracepoint
into an existing system is to write the trace point macro in the
trace header with one of the macros TRACE_EVENT, TRACE_FORMAT or
DECLARE_TRACE, then they must add the same named item into the C file
with the macro DEFINE_TRACE(name) and then add the trace point.

This change cuts out the needing to add the DEFINE_TRACE(name).
Every file that uses the tracepoint must still include the trace/<type>.h
file, but the one C file must also add a define before the including
of that file.

 #define CREATE_TRACE_POINTS
 #include <trace/mytrace.h>

This will cause the trace/mytrace.h file to also produce the C code
necessary to implement the trace point.

Note, if more than one trace/<type>.h is used to create the C code
it is best to list them all together.

 #define CREATE_TRACE_POINTS
 #include <trace/foo.h>
 #include <trace/bar.h>
 #include <trace/fido.h>

Thanks to Mathieu Desnoyers and Christoph Hellwig for coming up with
the cleaner solution of the define above the includes over my first
design to have the C code include a "special" header.

This patch converts sched, irq and lockdep and skb to use this new
method.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Impact: clean up

Neil Horman (et. al.) criticized the way the trace events were broken up
into two files. The reason for that was that ftrace needed to separate out
the declarations from where the #include <linux/tracepoint.h> was used.
It then dawned on me that the tracepoint.h header only needs to define the
TRACE_EVENT macro if it is not already defined.

The solution is simply to test if TRACE_EVENT is defined, and if it is not
then the linux/tracepoint.h header can define it. This change consolidates
all the <traces>.h and <traces>_event_types.h into the <traces>.h file.
Reported-by: NNeil Horman <nhorman@tuxdriver.com>
Reported-by: NTheodore Tso <tytso@mit.edu>
Reported-by: NJiaying Zhang <jiayingz@google.com>
Cc: Zhaolei <zhaolei@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

This patch allows event filters to be safely removed or switched
on-the-fly while avoiding the use of rcu or the suspension of tracing of
previous versions.

It does it by adding a new filter_pred_none() predicate function which
does nothing and by never deallocating either the predicates or any of
the filter_pred members used in matching; the predicate lists are
allocated and initialized during ftrace_event_calls initialization.

Whenever a filter is removed or replaced, the filter_pred_* functions
currently in use by the affected ftrace_event_call are immediately
switched over to to the filter_pred_none() function, while the rest of
the filter_pred members are left intact, allowing any currently
executing filter_pred_* functions to finish up, using the values they're
currently using.

In the case of filter replacement, the new predicate values are copied
into the old predicates after the above step, and the filter_pred_none()
functions are replaced by the filter_pred_* functions for the new
filter.  In this case, it is possible though very unlikely that a
previous filter_pred_* is still running even after the
filter_pred_none() switch and the switch to the new filter_pred_*.  In
that case, however, because nothing has been deallocated in the
filter_pred, the worst that can happen is that the old filter_pred_*
function sees the new values and as a result produces either a false
positive or a false negative, depending on the values it finds.

So one downside to this method is that rarely, it can produce a bad
match during the filter switch, but it should be possible to live with
that, IMHO.

The other downside is that at least in this patch the predicate lists
are always pre-allocated, taking up memory from the start.  They could
probably be allocated on first-use, and de-allocated when tracing is
completely stopped - if this patch makes sense, I could create another
one to do that later on.

Oh, and it also places a restriction on the size of __arrays in events,
currently set to 128, since they can't be larger than the now embedded
str_val arrays in the filter_pred struct.
Signed-off-by: NTom Zanussi <tzanussi@gmail.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: paulmck@linux.vnet.ibm.com
LKML-Reference: <1239610670.6660.49.camel@tropicana>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Merge reason: merge latest tracing fixes to avoid conflicts in
              kernel/trace/trace_events_filter.c with upcoming change
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch changes filter_check_discard() to make use of the new
ring_buffer_discard_commit() function and modifies the current users to
call the old commit function in the non-discard case.

It also introduces a version of filter_check_discard() that uses the
global trace buffer (filter_current_check_discard()) for those cases.

v2 changes:

- fix compile error noticed by Ingo Molnar
Signed-off-by: NTom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: fweisbec@gmail.com
LKML-Reference: <1239178554.10295.36.camel@tropicana>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add a new config option, CONFIG_EVENT_TRACING that gets selected
when CONFIG_TRACING is selected and adds everything needed by the stuff
in trace_export - basically all the event tracing support needed by e.g.
bprint, minus the actual events, which are only included if
CONFIG_EVENT_TRACER is selected.

So CONFIG_EVENT_TRACER can be used to turn on or off the generated events
(what I think of as the 'event tracer'), while CONFIG_EVENT_TRACING turns
on or off the base event tracing support used by both the event tracer and
the other things such as bprint that can't be configured out.
Signed-off-by: NTom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: fweisbec@gmail.com
LKML-Reference: <1239178441.10295.34.camel@tropicana>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The ring_buffer_discard_commit makes better usage of the ring_buffer
when an event has been discarded. It tries to remove it completely if
possible.

This patch converts the trace event filtering to use
ring_buffer_discard_commit instead of the ring_buffer_event_discard.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The ring_buffer_discard_commit is similar to ring_buffer_event_discard
but it can only be done on an event that has yet to be commited.
Unpredictable results can happen otherwise.

The main difference between ring_buffer_discard_commit and
ring_buffer_event_discard is that ring_buffer_discard_commit will try
to free the data in the ring buffer if nothing has addded data
after the reserved event. If something did, then it acts almost the
same as ring_buffer_event_discard followed by a
ring_buffer_unlock_commit.

Note, either ring_buffer_commit_discard and ring_buffer_unlock_commit
can be called on an event, not both.

This commit also exports both discard functions to be usable by
GPL modules.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Frederic Weisbecker suggested that the trace_special event shouldn't be
filterable; this patch adds a TRACE_EVENT_FORMAT_NOFILTER event macro
that allows an event format to be exported without having a filter
attached, and removes filtering from the trace_special event.
Signed-off-by: NTom Zanussi <tzanussi@gmail.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch adds run-time field descriptions to all the event formats
exported using TRACE_EVENT_FORMAT.  It also hooks up all the tracers
that use them (i.e. the tracers in the 'ftrace subsystem') so they can
also have their output filtered by the event-filtering mechanism.

When I was testing this, there were a couple of things that fooled me
into thinking the filters weren't working, when actually they were -
I'll mention them here so others don't make the same mistakes (and file
bug reports. ;-)

One is that some of the tracers trace multiple events e.g. the
sched_switch tracer uses the context_switch and wakeup events, and if
you don't set filters on all of the traced events, the unfiltered output
from the events without filters on them can make it look like the
filtering as a whole isn't working properly, when actually it is doing
what it was asked to do - it just wasn't asked to do the right thing.

The other is that for the really high-volume tracers e.g. the function
tracer, the volume of filtered events can be so high that it pushes the
unfiltered events out of the ring buffer before they can be read so e.g.
cat'ing the trace file repeatedly shows either no output, or once in
awhile some output but that isn't there the next time you read the
trace, which isn't what you normally expect when reading the trace file.
If you read from the trace_pipe file though, you can catch them before
they disappear.

Changes from v1:

As suggested by Frederic Weisbecker:

- get rid of externs in functions
- added unlikely() to filter_check_discard()
Signed-off-by: NTom Zanussi <tzanussi@gmail.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

* git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild-fixes:
  docbook: make cleandocs
  kbuild: fix spurious initramfs rebuild
  Documentation: explain the difference between __bitwise and __bitwise__
  kbuild: make it possible for the linker to discard local symbols from vmlinux
  kbuild: remove pointless strdup() on arguments passed to new_module() in modpost
  kbuild: fix a few typos in top-level Makefile
  kbuild: introduce destination-y for exported headers
  kbuild: use git svn instead of git-svn in setlocalversion
  kconfig: fix update-po-config to accect backslash in input
  kbuild: fix option processing for -I in headerdep

* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev:
  ata: fix obviously wrong comment
  ahci: force CAP_NCQ for earlier NV MCPs
  [libata] sata_via: kill uninit'd var warning

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: (22 commits)
  Input: i8042 - add HP DV9700 to the noloop list
  Input: arrange drivers/input/misc/Makefile in alphabetical order
  Input: add AD7879 Touchscreen driver
  Input: add AD7877 touchscreen driver
  Input: bf54x-keys - fix typo in warning
  Input: add driver for S1 button of rb532
  Input: generic driver for rotary encoders on GPIOs
  Input: hilkbd - fix crash when removing hilkbd module
  Input: atkbd - add quirk for Fujitsu Siemens Amilo PA 1510
  Input: atkbd - consolidate force release quirk setup
  Input: add accelerated touchscreen support for Marvell Zylonite
  Input: ucb1400_ts, mainstone-wm97xx - add BTN_TOUCH events
  Input: wm97xx - use disable_irq_nosync() for Mainstone
  Input: wm97xx - add BTN_TOUCH event to wm97xx to use it with Android
  Input: fix polling of /proc/bus/input/devices
  Input: psmouse - add newline to OLPC HGPK touchpad debugging
  Input: ati_remote2 - check module params
  Input: ati_remote2 - add per device attrs
  Input: ati_remote2 - complete suspend support
  Input: stop autorepeat timer on key release
  ...

There is a race between resume from hibernation and the asynchronous
scanning of SCSI devices and to prevent it from happening we need to
call scsi_complete_async_scans() during resume from hibernation.

In addition, if the resume from hibernation is userland-driven, it's
better to wait for all device probes in the kernel to complete before
attempting to open the resume device.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* git://git.infradead.org/iommu-2.6:
  intel-iommu: Avoid panic() for DRHD at address zero.
  Intel-IOMMU Alignment Issue in dma_pte_clear_range()

Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: add linux kernel support for YMM state
  x86: fix wrong section of pat_disable & make it static
  x86: Fix section mismatches in mpparse
  x86: fix set_fixmap to use phys_addr_t
  x86: Document get_user_pages_fast()
  x86, intr-remap: fix eoi for interrupt remapping without x2apic

Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  tracing/filters: return proper error code when writing filter file
  tracing/filters: allow user input integer to be oct or hex
  tracing/filters: fix NULL pointer dereference
  tracing/filters: NIL-terminate user input filter
  ftrace: Output REC->var instead of __entry->var for trace format
  Make __stringify support variable argument macros too
  tracing: fix document references
  tracing: fix splice return too large
  tracing: update file->f_pos when splice(2) it
  tracing: allocate page when needed
  tracing: disable seeking for trace_pipe_raw

Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  lockdep: continue lock debugging despite some taints
  lockdep: warn about lockdep disabling after kernel taint

Atttempting to rid us of the problematic work_on_cpu().  Just use
smp_call_fuction_single() here.

This repairs a 10% sysbench(oltp)+mysql regression which Mike reported,
due to

  commit 6b44003e
  Author: Andrew Morton <akpm@linux-foundation.org>
  Date:   Thu Apr 9 09:50:37 2009 -0600

      work_on_cpu(): rewrite it to create a kernel thread on demand

It seems that the kernel calls these acpi-cpufreq functions at a quite
high frequency.

Valdis Kletnieks also reports that this causes 70-90 forks per second on
his hardware.

Cc: Valdis.Kletnieks@vt.edu
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Zhao Yakui <yakui.zhao@intel.com>
Acked-by: NDave Jones <davej@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Tested-by: NMike Galbraith <efault@gmx.de>
Cc: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NIngo Molnar <mingo@elte.hu>
[ Made it use smp_call_function_many() instead of looping over cpu's
  with smp_call_function_single()    - Linus ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'i2c-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6:
  i2c: Let new-style drivers implement attach_adapter
  i2c: Fix sparse warnings for I2C_BOARD_INFO()
  i2c-voodoo3: Deprecate in favor of tdfxfb
  i2c-algo-pca: Fix use of uninitialized variable in debug message

When POSIX capabilities were introduced during the 2.1 Linux
cycle, the fs mask, which represents the capabilities which having
fsuid==0 is supposed to grant, did not include CAP_MKNOD and
CAP_LINUX_IMMUTABLE.  However, before capabilities the privilege
to call these did in fact depend upon fsuid==0.

This patch introduces those capabilities into the fsmask,
restoring the old behavior.

See the thread starting at http://lkml.org/lkml/2009/3/11/157 for
reference.

Note that if this fix is deemed valid, then earlier kernel versions (2.4
and 2.2) ought to be fixed too.

Changelog:
	[Mar 23] Actually delete old CAP_FS_SET definition...
	[Mar 20] Updated against J. Bruce Fields's patch
Reported-by: NIgor Zhbanov <izh1979@gmail.com>
Signed-off-by: NSerge E. Hallyn <serue@us.ibm.com>
Cc: stable@kernel.org
Cc: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'gm_20090410' of git://repo.or.cz/linux-2.6/trivial-mods:
  MAINTAINERS - Update MN10300 patterns
  MAINTAINERS - Update frv arch patterns
  scripts/get_maintainer.pl - Allow multiple files on command line
  MAINTAINERS - Update Freescale sound patterns
  MAINTAINERS - Add additional patterns
  MAINTAINERS - Add missing "/" to some pattern directories
  MAINTAINERS - Update DRIVER CORE patterns
  MAINTAINERS - Update M68K patterns
  MAINTAINERS - Coalesce sections "DVB" and "Video for Linux"
  MAINTAINERS - Remove cyblafb frame buffer no longer in tree
  MAINTAINERS - Remove x86/Voyager no longer in tree
  MAINTAINERS - Update FPU Emulator contact address and web page
  MAINTAINERS - i2c_tiny_usb T: should be W:
  MAINTAINERS - Add Linus Torvalds' git
  MAINTAINERS - standardize "T:       git urls"
  MAINTAINERS - Remove HP Fibre Channel HBA no longer in tree
  MAINTAINERS - Standardize style
  MAINTAINERS - Add file patterns
  Add scripts/get_maintainer.pl
Acked-by: NPavel Machek <pavel@ucw.cz>
Acked-by: NAndrew Morton <akpm@linux-foundation.org>

Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  percpu: unbreak alpha percpu
  mutex: have non-spinning mutexes on s390 by default

* 'for-linus' of git://git.o-hand.com/linux-rpurdie-leds:
  leds: just ignore invalid GPIOs in leds-gpio

* git://git.kernel.org/pub/scm/linux/kernel/git/wim/linux-2.6-watchdog:
  [WATCHDOG] omap_wdt.c: move probe function to .devinit.text
  [WATCHDOG] ks8695_wdt.c: move probe function to .devinit.text
  [WATCHDOG] at91rm9200_wdt.c: move probe function to .devinit.text
  [WATCHDOG] remove ARM26 sections
  [WATCHDOG] orion5x_wdt: Add shutdown callback, use watchdog ping function
  [WATCHDOG] i6300esb.c: Restructure initialization of the device
  [WATCHDOG] i6300esb.c: Fix the GETSTATUS and GETBOOTSTATUS ioctls.
  [WATCHDOG] i6300esb.c: Cleanup

* 'for-linus' of git://git.monstr.eu/linux-2.6-microblaze: (60 commits)
  microblaze_v8: Add MAINTAINERS fragment
  microblaze_v8: Uartlite for Microblaze
  microblaze_v8: Makefiles for Microblaze cpu
  microblaze_v8: Kconfig patches
  microblaze_v8: Interrupt handling and timer support
  microblaze_v8: syscalls.h
  microblaze_v8: pci headers
  microblaze_v8: Kbuild file
  microblaze_v8: string.h thread_info.h
  microblaze_v8: unistd.h
  microblaze_v8: fcntl.h sockios.h ucontext.h
  microblaze_v8: pool.h socket.h
  microblaze_v8: device.h param.h topology.h
  microblaze_v8: headers files entry.h current.h mman.h registers.h sembuf.h
  microblaze_v8: namei.h
  microblaze_v8: gpio.h, serial.h
  microblaze_v8: headers simple files - empty or redirect to asm-generic
  microblaze_v8: sigcontext.h siginfo.h
  microblaze_v8: termbits.h termios.h
  microblaze_v8: stats headers
  ...

While it isn't the way the standard device binding model works, it is
OK for new-style drivers to implement attach_adapter. It may help
convert the renaming legacy drivers to new style drivers faster.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Cc: David Brownell <dbrownell@users.sourceforge.net>

Since the first argument to I2C_BOARD_INFO() must be a string constant,
there is no need to parenthesise it, and adding parentheses results in
an invalid initialiser for char[].  gcc obviously accepts this syntax as
an extension, but sparse complains, e.g.:

drivers/net/sfc/boards.c:173:2: warning: array initialized from parenthesized string constant

Therefore, remove the parentheses.
Signed-off-by: NBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: NJean Delvare <khali@linux-fr.org>

Support for I2C/DDC was recently added to the tdfxfb driver, which
means that the i2c-voodoo3 driver can be deprecated.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Cc: Krzysztof Helt <krzysztof.h1@wp.pl>

A recent change broke debugging of pca_xfer(), fix it.
Reported-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Acked-by: NWolfram Sang <w.sang@pengutronix.de>

Also remove the now-useless debug printouts which are supposed to
tell us when the scan starts and ends.
Signed-off-by: NVegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Along with MCP65, MCP67 and 73 also don't set CAP_NCQ.  Force it.
Reported by zaceni@yandex.ru on bko#13014 and confirmed by Peer Chen.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NNightFox <zaceni2@yandex.ru>
Cc: Peer Chen <pchen@nvidia.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Reported and initial patch by Marin Mitov.
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Impact: broaden lockdep checks

Lockdep is disabled after any kernel taints. This might be convenient
to ignore bad locking issues which sources come from outside the kernel
tree. Nevertheless, it might be a frustrating experience for the
staging developers or those who experience a warning but are focused
on another things that require lockdep.

The v2 of this patch simply don't disable anymore lockdep in case
of TAINT_CRAP and TAINT_WARN events.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: LTP <ltp-list@lists.sourceforge.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg KH <gregkh@suse.de>
LKML-Reference: <1239412638-6739-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: provide useful missing info for developers

Kernel taint can occur in several situations such as warnings,
load of prorietary or staging modules, bad page, etc...

But when such taint happens, a developer might still be working on
the kernel, expecting that lockdep is still enabled. But a taint
disables lockdep without ever warning about it.
Such a kernel behaviour doesn't really help for kernel development.

This patch adds this missing warning.

Since the taint is done most of the time after the main message that
explain the real source issue, it seems safe to warn about it inside
add_taint() so that it appears at last, without hurting the main
information.

v2: Use a generic helper to disable lockdep instead of an
    open coded xchg().
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1239412638-6739-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>