linux-toradex.git/kernel/trace, branch v3.4-rc2-rt1

ring-buffer/rt: Check for irqs disabled before grabbing reader lock

2012-04-10T21:41:05+00:00

In RT the reader lock is a mutex and we can not grab it when preemption is
disabled. The in_atomic() check that is there does not check if irqs are
disabled. Add that check as well.

Signed-off-by: Steven Rostedt 
Cc: Carsten Emde 
Cc: John Kacur 
Cc: Peter Zijlstra 
Cc: Clark Williams 
Cc: stable-rt@vger.kernel.org
Link: http://lkml.kernel.org/r/20120301190345.786365803@goodmis.org
Signed-off-by: Thomas Gleixner

ring-buffer: Convert reader_lock from raw_spin_lock into spin_lock

2012-04-10T21:40:41+00:00

The reader_lock is mostly taken in normal context with interrupts enabled.
But because ftrace_dump() can happen anywhere, it is used as a spin lock
and in some cases a check to in_nmi() is performed to determine if the
ftrace_dump() was initiated from an NMI and if it is, the lock is not taken.

But having the lock as a raw_spin_lock() causes issues with the real-time
kernel as the lock is held during allocation and freeing of the buffer.
As memory locks convert into mutexes, keeping the reader_lock as a spin_lock
causes problems.

Converting the reader_lock is not straight forward as we must still deal
with the ftrace_dump() happening not only from an NMI but also from
true interrupt context in PREEPMT_RT.

Two wrapper functions are created to take and release the reader lock:

  int read_buffer_lock(cpu_buffer, unsigned long *flags)
  void read_buffer_unlock(cpu_buffer, unsigned long flags, int locked)

The read_buffer_lock() returns 1 if it actually took the lock, disables
interrupts and updates the flags. The only time it returns 0 is in the
case of a ftrace_dump() happening in an unsafe context.

The read_buffer_unlock() checks the return of locked and will simply
unlock the spin lock if it was successfully taken.

Instead of just having this in specific cases that the NMI might call
into, all instances of the reader_lock is converted to the wrapper
functions to make this a bit simpler to read and less error prone.

Signed-off-by: Steven Rostedt 
Cc: Peter Zijlstra 
Cc: Clark Williams 
Link: http://lkml.kernel.org/r/1317146210.26514.33.camel@gandalf.stny.rr.com
Signed-off-by: Thomas Gleixner

ftrace-crap.patch

2012-04-10T21:40:41+00:00

Signed-off-by: Thomas Gleixner

sched: Generic migrate_disable

2012-04-10T21:40:39+00:00

Make migrate_disable() be a preempt_disable() for !rt kernels. This
allows generic code to use it but still enforces that these code
sections stay relatively small.

A preemptible migrate_disable() accessible for general use would allow
people growing arbitrary per-cpu crap instead of clean these things
up.

Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-275i87sl8e1jcamtchmehonm@git.kernel.org

tracing: Show padding as unsigned short

2012-04-10T21:40:38+00:00

RT added two bytes to trace migrate disable counting to the trace events
and used two bytes of the padding to make the change. The structures and
all were updated correctly, but the display in the event formats was
not:

cat /debug/tracing/events/sched/sched_switch/format

name: sched_switch
ID: 51
format:
	field:unsigned short common_type;	offset:0;	size:2;	signed:0;
	field:unsigned char common_flags;	offset:2;	size:1;	signed:0;
	field:unsigned char common_preempt_count;	offset:3;	size:1;	signed:0;
	field:int common_pid;	offset:4;	size:4;	signed:1;
	field:unsigned short common_migrate_disable;	offset:8;	size:2;	signed:0;
	field:int common_padding;	offset:10;	size:2;	signed:0;


The field for common_padding has the correct size and offset, but the
use of "int" might confuse some parsers (and people that are reading
it). This needs to be changed to "unsigned short".

Signed-off-by: Steven Rostedt 
Link: http://lkml.kernel.org/r/1321467575.4181.36.camel@frodo
Cc: stable-rt@vger.kernel.org
Signed-off-by: Thomas Gleixner

ftrace-migrate-disable-tracing.patch

2012-04-10T21:40:38+00:00

Signed-off-by: Thomas Gleixner

latency-hist.patch

2012-04-10T21:40:02+00:00

This patch provides a recording mechanism to store data of potential
sources of system latencies. The recordings separately determine the
latency caused by a delayed timer expiration, by a delayed wakeup of the
related user space program and by the sum of both. The histograms can be
enabled and reset individually. The data are accessible via the debug
filesystem. For details please consult Documentation/trace/histograms.txt.

Signed-off-by: Carsten Emde 
Signed-off-by: Thomas Gleixner

Merge branch 'akpm' (Andrew's patch-bomb)

2012-04-05T22:30:34+00:00

Merge batch of fixes from Andrew Morton:
 "The simple_open() cleanup was held back while I wanted for laggards to
  merge things.

  I still need to send a few checkpoint/restore patches.  I've been
  wobbly about merging them because I'm wobbly about the overall
  prospects for success of the project.  But after speaking with Pavel
  at the LSF conference, it sounds like they're further toward
  completion than I feared - apparently davem is at the "has stopped
  complaining" stage regarding the net changes.  So I need to go back
  and re-review those patchs and their (lengthy) discussion."

* emailed from Andrew Morton : (16 patches)
  memcg swap: use mem_cgroup_uncharge_swap fix
  backlight: add driver for DA9052/53 PMIC v1
  C6X: use set_current_blocked() and block_sigmask()
  MAINTAINERS: add entry for sparse checker
  MAINTAINERS: fix REMOTEPROC F: typo
  alpha: use set_current_blocked() and block_sigmask()
  simple_open: automatically convert to simple_open()
  scripts/coccinelle/api/simple_open.cocci: semantic patch for simple_open()
  libfs: add simple_open()
  hugetlbfs: remove unregister_filesystem() when initializing module
  drivers/rtc/rtc-88pm860x.c: fix rtc irq enable callback
  fs/xattr.c:setxattr(): improve handling of allocation failures
  fs/xattr.c:listxattr(): fall back to vmalloc() if kmalloc() failed
  fs/xattr.c: suppress page allocation failure warnings from sys_listxattr()
  sysrq: use SEND_SIG_FORCED instead of force_sig()
  proc: fix mount -t proc -o AAA

simple_open: automatically convert to simple_open()

2012-04-05T22:25:50+00:00

Many users of debugfs copy the implementation of default_open() when
they want to support a custom read/write function op.  This leads to a
proliferation of the default_open() implementation across the entire
tree.

Now that the common implementation has been consolidated into libfs we
can replace all the users of this function with simple_open().

This replacement was done with the following semantic patch:


@ open @
identifier open_f != simple_open;
identifier i, f;
@@
-int open_f(struct inode *i, struct file *f)
-{
(
-if (i->i_private)
-f->private_data = i->i_private;
|
-f->private_data = i->i_private;
)
-return 0;
-}

@ has_open depends on open @
identifier fops;
identifier open.open_f;
@@
struct file_operations fops = {
...
-.open = open_f,
+.open = simple_open,
...
};


[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Stephen Boyd 
Cc: Greg Kroah-Hartman 
Cc: Al Viro 
Cc: Julia Lawall 
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

tracing: Fix ent_size in trace output

2012-03-27T16:05:44+00:00

When reading the trace file, the records of each of the per_cpu buffers
are examined to find the next event to print out. At the point of looking
at the event, the size of the event is recorded. But if the first event is
chosen, the other events in the other CPU buffers will reset the event size
that is stored in the iterator descriptor, causing the event size passed to
the output functions to be incorrect.

In most cases this is not a problem, but for the case of stack traces, it
is. With the change to the stack tracing to record a dynamic number of
back traces, the output depends on the size of the entry instead of the
fixed 8 back traces. When the entry size is not correct, the back traces
would not be fully printed.

Note, reading from the per-cpu trace files were not affected.

Reported-by: Thomas Gleixner 
Tested-by: Thomas Gleixner 
Cc: stable@vger.kernel.org
Signed-off-by: Steven Rostedt