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>

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>

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>

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>

BLK_TC_PC events should be treated differently with BLK_TC_FS events.

Before this patch:

 # echo 1 > /sys/block/sda/sda1/trace/enable
 # echo pc > /sys/block/sda/sda1/trace/act_mask
 # echo blk > /debugfs/tracing/current_tracer
 # (generate some BLK_TC_PC events)
 # cat trace
        bash-2184  [000]  1774.275413:   8,7    I   N [bash]
        bash-2184  [000]  1774.275435:   8,7    D   N [bash]
        bash-2184  [000]  1774.275540:   8,7    I   R [bash]
        bash-2184  [000]  1774.275547:   8,7    D   R [bash]
 ksoftirqd/0-4     [000]  1774.275580:   8,7    C   N 0 [0]
        bash-2184  [000]  1774.275648:   8,7    I   R [bash]
        bash-2184  [000]  1774.275653:   8,7    D   R [bash]
 ksoftirqd/0-4     [000]  1774.275682:   8,7    C   N 0 [0]
        bash-2184  [000]  1774.275739:   8,7    I   R [bash]
        bash-2184  [000]  1774.275744:   8,7    D   R [bash]
 ksoftirqd/0-4     [000]  1774.275771:   8,7    C   N 0 [0]
        bash-2184  [000]  1774.275804:   8,7    I   R [bash]
        bash-2184  [000]  1774.275808:   8,7    D   R [bash]
 ksoftirqd/0-4     [000]  1774.275836:   8,7    C   N 0 [0]

After this patch:

 # cat trace
        bash-2263  [000]   366.782149:   8,7    I   N 0 (00 ..) [bash]
        bash-2263  [000]   366.782323:   8,7    D   N 0 (00 ..) [bash]
        bash-2263  [000]   366.782557:   8,7    I   R 8 (25 00 ..) [bash]
        bash-2263  [000]   366.782560:   8,7    D   R 8 (25 00 ..) [bash]
 ksoftirqd/0-4     [000]   366.782582:   8,7    C   N (25 00 ..) [0]
        bash-2263  [000]   366.782648:   8,7    I   R 8 (5a 00 3f 00) [bash]
        bash-2263  [000]   366.782650:   8,7    D   R 8 (5a 00 3f 00) [bash]
 ksoftirqd/0-4     [000]   366.782669:   8,7    C   N (5a 00 3f 00) [0]
        bash-2263  [000]   366.782710:   8,7    I   R 8 (5a 00 08 00) [bash]
        bash-2263  [000]   366.782713:   8,7    D   R 8 (5a 00 08 00) [bash]
 ksoftirqd/0-4     [000]   366.782730:   8,7    C   N (5a 00 08 00) [0]
        bash-2263  [000]   366.783375:   8,7    I   R 36 (5a 00 08 00) [bash]
        bash-2263  [000]   366.783379:   8,7    D   R 36 (5a 00 08 00) [bash]
 ksoftirqd/0-4     [000]   366.783404:   8,7    C   N (5a 00 08 00) [0]

This is what we do with PC events in user-space blktrace.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49D32387.9040106@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Not all events are pc (packet command) events. An event is a pc
event only if it has BLK_TC_PC bit set.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49D3236D.3090705@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: refactor code for future changes

Current kmemtrace.h is used both as header file of kmemtrace and kmem's
tracepoints definition.

Tracepoints' definition file may be used by other code, and should only have
definition of tracepoint.

We can separate include/trace/kmemtrace.h into 2 files:

  include/linux/kmemtrace.h: header file for kmemtrace
  include/trace/kmem.h:      definition of kmem tracepoints
Signed-off-by: NZhao Lei <zhaolei@cn.fujitsu.com>
Acked-by: NEduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Acked-by: NPekka Enberg <penberg@cs.helsinki.fi>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <49DEE68A.5040902@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

- propagate return value of filter_add_pred() to the user

- return -ENOSPC but not -ENOMEM or -EINVAL when the filter array
  is full
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NTom Zanussi <tzanussi@gmail.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49E04CF0.3010105@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Before patch:

 # echo 'parent_pid == 0x10' > events/sched/sched_process_fork/filter
 # cat sched/sched_process_fork/filter
 parent_pid == 0

After patch:

 # cat sched/sched_process_fork/filter
 parent_pid == 16

Also check the input more strictly.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NTom Zanussi <tzanussi@gmail.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49E04C53.4010600@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Try this, and you'll see NULL pointer dereference bug:

  # echo -n 'parent_comm ==' > sched/sched_process_fork/filter

Because we passed NULL ptr to simple_strtoull().
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NTom Zanussi <tzanussi@gmail.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49E04C43.1050504@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Make sure messages from user space are NIL-terminated strings,
otherwise we could dump random memory while reading filter file.

Try this:
 # echo 'parent_comm ==' > events/sched/sched_process_fork/filter
 # cat events/sched/sched_process_fork/filter
 parent_comm == �
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NTom Zanussi <tzanussi@gmail.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49E04C32.6060508@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Several drivers use asynchronous work to do device discovery, and we
synchronize with them in the compiled-in case before we actually try to
mount root filesystems etc.

However, when compiled as modules, that synchronization is missing - the
module loading completes, but the driver hasn't actually finished
probing for devices, and that means that any user mode that expects to
use the devices after the 'insmod' is now potentially broken.

We already saw one case of a similar issue in the ACPI battery code,
where the kernel itself expected the module to be all done, and unmapped
the init memory - but the async device discovery was still running.
That got hacked around by just removing the "__init" (see commit
5d38258e "ACPI battery: fix async boot
oops"), but the real fix is to just make the module loading wait for all
async work to be completed.

It will slow down module loading, but since common devices should be
built in anyway, and since the bug is really annoying and hard to handle
from user space (and caused several S3 resume regressions), the simple
fix to wait is the right one.

This fixes at least

	http://bugzilla.kernel.org/show_bug.cgi?id=13063

but probably a few other bugzilla entries too (12936, for example), and
is confirmed to fix Rafael's storage driver breakage after resume bug
report (no bugzilla entry).

We should also be able to now revert that ACPI battery fix.
Reported-and-tested-by: NRafael J. Wysocki <rjw@suse.com>
Tested-by: NHeinz Diehl <htd@fancy-poultry.org>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

print fmt: "irq=%d return=%s", __entry->irq, __entry->ret ? \"handled\" : \"unhandled\"

"__entry" should be convert to "REC" by __stringify() macro.
Signed-off-by: NZhao Lei <zhaolei@cn.fujitsu.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49DC679D.2090901@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When moving documents to Documentation/trace/, I forgot to
grep Kconfig to find out those references.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Pekka Paalanen <pq@iki.fi>
Cc: eduard.munteanu@linux360.ro
LKML-Reference: <49DE97EF.7080208@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

While trying to optimize the new lock on reiserfs to replace
the bkl, I find the lock tracing very useful though it lacks
something important for performance (and latency) instrumentation:
the time a task waits for a lock.

That's what this patch implements:

  bash-4816  [000]   202.652815: lock_contended: lock_contended: &sb->s_type->i_mutex_key
  bash-4816  [000]   202.652819: lock_acquired: &rq->lock (0.000 us)
 <...>-4787  [000]   202.652825: lock_acquired: &rq->lock (0.000 us)
 <...>-4787  [000]   202.652829: lock_acquired: &rq->lock (0.000 us)
  bash-4816  [000]   202.652833: lock_acquired: &sb->s_type->i_mutex_key (16.005 us)

As shown above, the "lock acquired" field is followed by the time
it has been waiting for the lock. Usually, a lock contended entry
is followed by a near lock_acquired entry with a non-zero time waited.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1238975373-15739-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

I got these from strace:

 splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 12288
 splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 12288
 splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 12288
 splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 16384
 splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 8192
 splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 8192
 splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 8192

I wanted to splice_read 4096 bytes, but it returns 8192 or larger.

It is because the return value of tracing_buffers_splice_read()
does not include "zero out any left over data" bytes.

But tracing_buffers_read() includes these bytes, we make them
consistent.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49D46674.9030804@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: Cleanup

These two lines:

	if (unlikely(*ppos))
		return -ESPIPE;

in tracing_buffers_splice_read() are not needed, VFS layer
has disabled seek(2).

We remove these two lines, and then we can update file->f_pos.

And tracing_buffers_read() updates file->f_pos, this fix
make tracing_buffers_splice_read() updates file->f_pos too.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49D46670.4010503@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: Cleanup

Sometimes, we open trace_pipe_raw, but we don't read(2) it,
we just splice(2) it, thus, the page is not used.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49D4666B.4010608@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: disable pread()

We set tracing_buffers_fops.llseek to no_llseek,
but we can still perform pread() to read this file.

That is not expected.

This fix uses nonseekable_open() to disable it.

tracing_buffers_fops.llseek is still set to no_llseek,
it mark this file is a "non-seekable device" and is used by
sys_splice(). See also do_splice() or manual of splice(2):

ERRORS
       EINVAL Target file system doesn't support  splicing;
              neither  of the descriptors refers to a pipe;
              or offset given for non-seekable device.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49D46668.8030806@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: performance regression fix for s390

The adaptive spinning mutexes will not always do what one would expect on
virtualized architectures like s390. Especially the cpu_relax() loop in
mutex_spin_on_owner might hurt if the mutex holding cpu has been scheduled
away by the hypervisor.

We would end up in a cpu_relax() loop when there is no chance that the
state of the mutex changes until the target cpu has been scheduled again by
the hypervisor.

For that reason we should change the default behaviour to no-spin on s390.

We do have an instruction which allows to yield the current cpu in favour of
a different target cpu. Also we have an instruction which allows us to figure
out if the target cpu is physically backed.

However we need to do some performance tests until we can come up with
a solution that will do the right thing on s390.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
LKML-Reference: <20090409184834.7a0df7b2@osiris.boeblingen.de.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix kfree crash with non-standard act_mask string

If passing a string with leading white spaces to strstrip(),
the returned ptr != the original ptr.

This bug was introduced by me.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <49DD694C.8020902@cn.fujitsu.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix build warnings and possibe compat misbehavior on IA64

Building a kernel on ia64 might trigger these ugly build warnings:

CC      arch/ia64/ia32/sys_ia32.o
In file included from arch/ia64/ia32/sys_ia32.c:55:
arch/ia64/ia32/ia32priv.h:290:1: warning: "elf_check_arch" redefined
In file included from include/linux/elf.h:7,
                 from include/linux/module.h:14,
                 from include/linux/ftrace.h:8,
                 from include/linux/syscalls.h:68,
                 from arch/ia64/ia32/sys_ia32.c:18:
arch/ia64/include/asm/elf.h:19:1: warning: this is the location of the previous definition
[...]

sys_ia32.c includes linux/syscalls.h which in turn includes linux/ftrace.h
to import the syscalls tracing prototypes.

But including ftrace.h can pull too much things for a low level file,
especially on ia64 where the ia32 private headers conflict with higher
level headers.

Now we isolate the syscall tracing headers in their own lightweight file.
Reported-by: NTony Luck <tony.luck@intel.com>
Tested-by: NTony Luck <tony.luck@intel.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NTony Luck <tony.luck@intel.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jason Baron <jbaron@redhat.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Michael Rubin <mrubin@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Michael Davidson <md@google.com>
LKML-Reference: <20090408184058.GB6017@nowhere>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: circular locking bugfix

The various implemetnations and proposed implemetnations of work_on_cpu()
are vulnerable to various deadlocks because they all used queues of some
form.

Unrelated pieces of kernel code thus gained dependencies wherein if one
work_on_cpu() caller holds a lock which some other work_on_cpu() callback
also takes, the kernel could rarely deadlock.

Fix this by creating a short-lived kernel thread for each work_on_cpu()
invokation.

This is not terribly fast, but the only current caller of work_on_cpu() is
pci_call_probe().

It would be nice to find some other way of doing the node-local
allocations in the PCI probe code so that we can zap work_on_cpu()
altogether.  The code there is rather nasty.  I can't think of anything
simple at this time...

Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

kthreadd is the single thread which implements ths "create" request, move
sched_setscheduler/etc from create_kthread() to kthread_create() to
improve the scalability.

We should be careful with sched_setscheduler(), use _nochek helper.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Vitaliy Gusev <vgusev@openvz.org
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Remove the unnecessary find_task_by_pid_ns(). kthread() can just
use "current" to get the same result.
Signed-off-by: NVitaliy Gusev <vgusev@openvz.org>
Acked-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

This fixes all the checkpatch --file complaints about kernel/ptrace.c
and also removes an unused #include.  I've verified that there are no
changes to the compiled code on x86_64.
Signed-off-by: NRoland McGrath <roland@redhat.com>
[ Removed the parts that just split a line  - Linus ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

update_rlimit_cpu() tries to optimize out set_process_cpu_timer() in case
when we already have CPUCLOCK_PROF timer which should expire first. But it
uses cputime_lt() instead of cputime_gt().

Test case:

	int main(void)
	{
		struct itimerval it = {
			.it_value = { .tv_sec = 1000 },
		};

		assert(!setitimer(ITIMER_PROF, &it, NULL));

		struct rlimit rl = {
			.rlim_cur = 1,
			.rlim_max = 1,
		};

		assert(!setrlimit(RLIMIT_CPU, &rl));

		for (;;)
			;

		return 0;
	}

Without this patch, the task is not killed as RLIMIT_CPU demands.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Peter Lojkin <ia6432@inbox.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: stable@kernel.org
LKML-Reference: <20090327000610.GA10108@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

See http://bugzilla.kernel.org/show_bug.cgi?id=12911

copy_signal() copies signal->rlim, but RLIMIT_CPU is "lost". Because
posix_cpu_timers_init_group() sets cputime_expires.prof_exp = 0 and thus
fastpath_timer_check() returns false unless we have other expired cpu timers.

Change copy_signal() to set cputime_expires.prof_exp if we have RLIMIT_CPU.
Also, set cputimer.running = 1 in that case. This is not strictly necessary,
but imho makes sense.
Reported-by: NPeter Lojkin <ia6432@inbox.ru>
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Peter Lojkin <ia6432@inbox.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: stable@kernel.org
LKML-Reference: <20090327000607.GA10104@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>