While writing a new tracer, I had a bug where I caused the ring-buffer
to recurse in a bad way. The bug was with the tracer I was writing
and not the ring-buffer itself. But it took a long time to find the
problem.

This patch adds paranoid checks into the ring-buffer infrastructure
that will catch bugs of this nature.

Note: I put the bug back in the tracer and this patch showed the error
      nicely and prevented the lockup.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: ia64+tracing build fix

When a function is kprobed, the return address is set to the
kprobe_trampoline, or something similar. This caused the output
of the trace to look confusing when the parent seemed to be this
"kprobe_trampoline" function.

To fix this, Abhishek Sagar added a test of the instruction pointer
of the parent to see if it matched the kprobe_trampoline. If it
did, the output would print a "[unknown/kretprobe'd]" instead.

Unfortunately, not all archs do this the same way, and the trampoline
function may not be exported, which causes failures in builds.

This patch will compare the name instead of the pointer to see
if it matches. This prevents us from depending on a function from
being exported, and should work on all archs. The worst that can
happen is that an arch might use a different name and then we
go back to the confusing output. At least the arch will still build.
Reported-by: NAbhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Tested-by: NAbhishek Sagar <sagar.abhishek@gmail.com>
Acked-by: NAbhishek Sagar <sagar.abhishek@gmail.com>

Impact: build fix on !stacktrace architectures

only select STACKTRACE on architectures that have STACKTRACE_SUPPORT

... since we also need to ifdef out the guts of ftrace_trace_stack().
We also want to disallow setting TRACE_ITER_STACKTRACE in trace_flags
on such configs, but that can wait.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Acked-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Insufficient dependency - we really want CONFIG_RTC_CLASS=y there.
That will give us CONFIG_RTC_LIB=y, so the old dependency can be
simply replaced.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This one apparently doesn't generate any warnings, because the function
is only used during system bootup, when the warnings are disabled.  But
it's still very wrong.

The __reserve_region_with_split() function is called with the
resource_lock held for writing, so it must only ever do GFP_ATOMIC
allocations.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Impact: build fix on non-lockdep architectures

Some architectures do not support a way to read the irq flags that
is set from "local_irq_save(flags)" to determine if interrupts were
disabled or enabled. Ftrace uses this information to display to the user
if the trace occurred with interrupts enabled or disabled.

Besides the fact that those archs that do not support this will fail to
compile, unless they fix it, we do not want to have the trace simply
say interrupts were not disabled or they were enabled, without knowing
the real answer.

This patch adds a 'X' in the output to let the user know that the
architecture they are running on does not support a way for the tracer
to determine if interrupts were enabled or disabled. It also lets those
same archs compile with tracing enabled.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Currently "kill <sig> -1" kills processes in all namespaces and breaks the
isolation of namespaces.  Earlier attempt to fix this was discussed at:

	http://lkml.org/lkml/2008/7/23/148

As suggested by Oleg Nesterov in that thread, use "task_pid_vnr() > 1"
check since task_pid_vnr() returns 0 if process is outside the caller's
namespace.
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: NEric W. Biederman <ebiederm@xmission.com>
Tested-by: NDaniel Hokka Zakrisson <daniel@hozac.com>
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

profile_init() calls in to alloc_bootmem() on early initialization.  While
alloc_bootmem() is __init, the reference itself is safe in that it is
tucked below a !slab_is_available() check.  So, flag profile_init() as
__ref.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Just call unfreeze_cgroup() if goal_state == THAWED, and call
try_to_freeze_cgroup() if goal_state == FROZEN.

No behavior has been changed.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NCedric Le Goater <clg@fr.ibm.com>
Acked-by: NMatt Helsley <matthltc@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Don't duplicate the implementation of thaw_process().

[akpm@linux-foundation.org: make __thaw_process() static]
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Acked-by: NMatt Helsley <matthltc@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It is sufficient to check if @task is frozen, and no need to check if the
original freezer is frozen.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NCedric Le Goater <clg@fr.ibm.com>
Acked-by: NMatt Helsley <matthltc@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The BUG_ON() should be protected by freezer->lock, otherwise it can be
triggered easily when a task has been unfreezed but the corresponding
cgroup hasn't been changed to FROZEN state.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NCedric Le Goater <clg@fr.ibm.com>
Acked-by: NMatt Helsley <matthltc@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Impact: change /proc/sched/debug from rw-r--r-- to r--r--r--

/proc/sched_debug is read-only.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: build fix on non-function-tracing architectures

The trace_nop is the tracer that is defined when no tracer is set in
the ftrace infrastructure.

The trace_nop was mistakenly selected by HAVE_FTRACE due to the confusion
between ftrace infrastructure and the ftrace function tracer (which has
been solved by renaming the function tracer).

This patch changes the select to the approriate TRACING.

This patch should fix compile errors on architectures that do not define
the FUNCTION_TRACER.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: avoid false-positive WARN_ON()

Andi Kleen reported:
> When running x86info on a 2.6.27-git8 system I get
>
> resource map sanity check conflict: 0x9e000 0x9efff 0x10000 0x9e7ff System RAM
> ------------[ cut here ]------------
> WARNING: at /home/lsrc/linux/arch/x86/mm/ioremap.c:226 __ioremap_caller+0xf2/0x2d6()
> ...

Some of the pages below the 1MB ISA addresses will be shared typically by both
BIOS and system usable RAM. For example:
	BIOS-e820: 0000000000000000 - 000000000009f800 (usable)
	BIOS-e820: 000000000009f800 - 00000000000a0000 (reserved)

x86info reads the low physical address using /dev/mem, which internally
uses ioremap() for accessing non RAM pages. ioremap() of such low
pages conflicts with multiple resource entities leading to the
above warning.

Change the iomem_map_sanity_check() to allow mapping a page spanning multiple
resource entities (minimum granularity that one can map is a page anyhow).
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: corrects a bug which made the non-dyn function tracer not functional

With latest git, the non-dynamic function tracer didn't get any trace.

The problem was the fact that ftrace_enabled wasn't initialized to 1
because ftrace hasn't any init function when DYNAMIC_FTRACE is disabled.

So when a tracer tries to register an ftrace_ops struct,
__register_ftrace_function failed to set the hook.

This patch corrects it by setting an init function to initialize
ftrace during the boot.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The commit (in linux-tip) c2931e05
 ( ftrace: return an error when setting a nonexistent tracer )
added useful code that would error when a bad tracer was written into
the current_tracer file.

But this had a bug if the amount written was more than the amount read by
that code. The first iteration would set the tracer correctly, but since
it did not consume the rest of what was written (usually whitespace), the
userspace utility would continue to write what was not consumed. This
second iteration would fail to find a tracer and return -EINVAL. Funny
thing is that the tracer would have already been set.

This patch just consumes all the data that is written to the file.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix lockdep lock-api-caller output when irqsoff tracing is enabled

81d68a96 "ftrace: trace irq disabled critical timings" added wrappers around
trace_hardirqs_on/off_caller. However these functions use
__builtin_return_address(0) to figure out which function actually disabled
or enabled irqs. The result is that we save the ips of trace_hardirqs_on/off
instead of the real caller. Not very helpful.

However since the patch from Steven the ip already gets passed. So use that
and get rid of __builtin_return_address(0) in these two functions.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

When we failed to get tasklist_lock eventually (count equals 0),
we should only print " ignoring it.\n", and not print
" locked it.\n" needlessly.
Signed-off-by: NQinghuang Feng <qhfeng.kernel@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: build fix on Alpha

When tracing is enabled, some arch have included <linux/irqflags.h>
on their <asm/system.h> but others like alpha or m68k don't.

Build error on alpha:

kernel/trace/trace.c: In function 'tracing_cpumask_write':
kernel/trace/trace.c:2145: error: implicit declaration of function 'raw_local_irq_disable'
kernel/trace/trace.c:2162: error: implicit declaration of function 'raw_local_irq_enable'

Tested on Alpha through a cross-compiler (should correct a similar issue on m68k).
Reported-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: build fix

If the boot tracer is selected but not the sched_switch,
there will be a build failure:

 kernel/built-in.o: In function `boot_trace_init':
 trace_boot.c:(.text+0x5ee38): undefined reference to `sched_switch_trace'
 kernel/built-in.o: In function `disable_boot_trace':
 (.text+0x5eee1): undefined reference to `tracing_stop_cmdline_record'
 kernel/built-in.o: In function `enable_boot_trace':
 (.text+0x5ef11): undefined reference to `tracing_start_cmdline_record'

This patch fixes it.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix kernel crash that can trigger during tracing

If we try to remove a probe that has not been already registered,
the tracepoint_entry_remove_probe() function will dereference a NULL
pointer.

Check the probe before removing it to avoid crashes.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

A powerpc ppc64_defconfig build produces these warnings:

kernel/trace/ring_buffer.c: In function 'rb_add_time_stamp':
kernel/trace/ring_buffer.c:969: warning: format '%llu' expects type 'long long unsigned int', but argument 2 has type 'u64'
kernel/trace/ring_buffer.c:969: warning: format '%llu' expects type 'long long unsigned int', but argument 3 has type 'u64'
kernel/trace/ring_buffer.c:969: warning: format '%llu' expects type 'long long unsigned int', but argument 4 has type 'u64'

Just cast the u64s to unsigned long long like we do everywhere else.
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

/scratch/sfr/next/kernel/cgroup.c: In function 'cgroup_tasks_start':
/scratch/sfr/next/kernel/cgroup.c:2107: warning: unused variable 'i'

Introduced in commit cc31edce "cgroups:
convert tasks file to use a seq_file with shared pid array".
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This reverts commit a802dd0e by moving
the call to init_workqueues() back where it belongs - after SMP has been
initialized.

It also moves stop_machine_init() - which needs workqueues - to a later
phase using a core_initcall() instead of early_initcall().  That should
satisfy all ordering requirements, and was apparently the reason why
init_workqueues() was moved to be too early.

Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

this warning:

  kernel/trace/ftrace.c:189: warning: ‘frozen_record_count’ defined but not used

triggers because frozen_record_count is only used in the KCONFIG_MARKERS
case. Move the variable it there.

Alas, this frozen-record facility seems to have little use. The
frozen_record_count variable is not used by anything, nor the flags.

So this section might need a bit of dead-code-removal care as well.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Since we moved wakeup preemption back to virtual time, it makes sense to move
the buddy stuff back as well. The purpose of the buddy scheduling is to allow
a quickly scheduling pair of tasks to run away from the group as far as a
regular busy task would be allowed under wakeup preemption.

This has the advantage that the pair can ping-pong for a while, enjoying
cache-hotness. Without buddy scheduling other tasks would interleave destroying
the cache.

Also, it saves a word in cfs_rq.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The advantage is that vruntime based wakeup preemption has a better
conceptual model. Here wakeup_gran = 0 means: preempt when 'fair'.
Therefore wakeup_gran is the granularity of unfairness we allow in order
to make progress.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Mysql+oltp and pgsql+oltp peaks are still shifted right. The below puts
the peaks back to 1 client/server pair per core.

Use the avg_overlap information to weaken the sync hint.
Signed-off-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Mike noticed the current min_vruntime tracking can go wrong and skip the
current task. If the only remaining task in the tree is a nice 19 task
with huge vruntime, new tasks will be inserted too far to the right too,
causing some interactibity issues.

min_vruntime can only change due to the leftmost entry disappearing
(dequeue_entity()), or by the leftmost entry being incremented past the
next entry, which elects a new leftmost (__update_curr())

Due to the current entry not being part of the actual tree, we have to
compare the leftmost tree entry with the current entry, and take the
leftmost of these two.

So create a update_min_vruntime() function that takes computes the
leftmost vruntime in the system (either tree of current) and increases
the cfs_rq->min_vruntime if the computed value is larger than the
previously found min_vruntime. And call this from the two sites we've
identified that can change min_vruntime.
Reported-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

In one of the group load balancer patches:

	commit 408ed066
	Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
	Date:   Fri Jun 27 13:41:28 2008 +0200
	Subject: sched: hierarchical load vs find_busiest_group

The following change:

-               if (max_load - this_load + SCHED_LOAD_SCALE_FUZZ >=
+               if (max_load - this_load + 2*busiest_load_per_task >=
                                        busiest_load_per_task * imbn) {

made the condition always true, because imbn is [1,2].
Therefore, remove the 2*, and give the it a fair chance.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup, small kernel text size reduction, no functionality changed

reserve_region_with_split() calls in to __reserve_region_with_split(),
which is an __init function. The only caller of reserve_region_with_split()
is an __init function, so make it __init too.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

both log_buf_copy() and log_buf_len are unused.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Move free_module_param_attrs() into the CONFIG_MODULES section, since
it's only used inside there. Thus avoiding the warning

  kernel/params.c:514: warning: 'free_module_param_attrs' defined but not used
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fix:

 kernel/trace/ftrace.c: In function 'ftrace_release':
 kernel/trace/ftrace.c:271: error: implicit declaration of function 'ftrace_release_hash'

release_hash is not needed without dftraced.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>

Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>

The ftrace hash was used by the ftrace_daemon code. The record ip function
would place the calling address (ip) into the hash. The daemon would later
read the hash and modify that code.

The hash complicates the code. This patch removes it.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The arch dependent function ftrace_mcount_set was only used by the daemon
start up code. This patch removes it.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The ftrace daemon is complex and error prone.  This patch strips it out
of the code.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>