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  1. 12 11月, 2008 1 次提交
    • S
      ring-buffer: buffer record on/off switch · a3583244
      由 Steven Rostedt 提交于 
      Impact: enable/disable ring buffer recording API added

Several kernel developers have requested that there be a way to stop
recording into the ring buffers with a simple switch that can also
be enabled from userspace. This patch addes a new kernel API to the
ring buffers called:

 tracing_on()
 tracing_off()

When tracing_off() is called, all ring buffers will not be able to record
into their buffers.

tracing_on() will enable the ring buffers again.

These two act like an on/off switch. That is, there is no counting of the
number of times tracing_off or tracing_on has been called.

A new file is added to the debugfs/tracing directory called

  tracing_on

This allows for userspace applications to also flip the switch.

  echo 0 > debugfs/tracing/tracing_on

disables the tracing.

  echo 1 > /debugfs/tracing/tracing_on

enables it.

Note, this does not disable or enable any tracers. It only sets or clears
a flag that needs to be set in order for the ring buffers to write to
their buffers. It is a global flag, and affects all ring buffers.

The buffers start out with tracing_on enabled.

There are now three flags that control recording into the buffers:

 tracing_on: which affects all ring buffer tracers.

 buffer->record_disabled: which affects an allocated buffer, which may be set
     if an anomaly is detected, and tracing is disabled.

 cpu_buffer->record_disabled: which is set by tracing_stop() or if an
     anomaly is detected. tracing_start can not reenable this if
     an anomaly occurred.

The userspace debugfs/tracing/tracing_enabled is implemented with
tracing_stop() but the user space code can not enable it if the kernel
called tracing_stop().

Userspace can enable the tracing_on even if the kernel disabled it.
It is just a switch used to stop tracing if a condition was hit.
tracing_on is not for protecting critical areas in the kernel nor is
it for stopping tracing if an anomaly occurred. This is because userspace
can reenable it at any time.

Side effect: With this patch, I discovered a dead variable in ftrace.c
  called tracing_on. This patch removes it.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
      a3583244
  3. 11 11月, 2008 6 次提交
    • S
      ring-buffer: prevent infinite looping on time stamping · 4143c5cb
      由 Steven Rostedt 提交于 
      Impact: removal of unnecessary looping

The lockless part of the ring buffer allows for reentry into the code
from interrupts. A timestamp is taken, a test is preformed and if it
detects that an interrupt occurred that did tracing, it tries again.

The problem arises if the timestamp code itself causes a trace.
The detection will detect this and loop again. The difference between
this and an interrupt doing tracing, is that this will fail every time,
and cause an infinite loop.

Currently, we test if the loop happens 1000 times, and if so, it will
produce a warning and disable the ring buffer.

The problem with this approach is that it makes it difficult to perform
some types of tracing (tracing the timestamp code itself).

Each trace entry has a delta timestamp from the previous entry.
If a trace entry is reserved but and interrupt occurs and traces before
the previous entry is commited, the delta timestamp for that entry will
be zero. This actually makes sense in terms of tracing, because the
interrupt entry happened before the preempted entry was commited, so
one may consider the two happening at the same time. The order is
still preserved in the buffer.

With this idea, instead of trying to get a new timestamp if an interrupt
made it in between the timestamp and the test, the entry could simply
make the delta zero and continue. This will prevent interrupts or
tracers in the timer code from causing the above loop.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
      4143c5cb
    • S
      ftrace: disable tracing on resize · bf5e6519
      由 Steven Rostedt 提交于 
      Impact: fix for bug on resize

This patch addresses the bug found here:

 http://bugzilla.kernel.org/show_bug.cgi?id=11996

When ftrace converted to the new unified trace buffer, the resizing of
the buffer was not protected as much as it was originally. If tracing
is performed while the resize occurs, then the buffer can be corrupted.

This patch disables all ftrace buffer modifications before a resize
takes place.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
      bf5e6519
    • L
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6 · 3ad4f597
      由 Linus Torvalds 提交于 
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
  ALSA: hda - Make the HP EliteBook 8530p use AD1884A model laptop
  ALSA: gusextreme: Fix build errors
  ALSA: hdsp: check for iobox and upload firmware during ioctl
  ALSA: HDSP: check for io box before uploading firmware
  ALSA: hda - Add another HP model (6730s) for AD1884A
  alsa: fix snd_BUG_on() and friends
  ALSA: hda - Add a quirk for MEDION MD96630
  ALSA: hda - Limit the number of GPIOs show in proc
      3ad4f597
    • T
      Merge branches 'topic/fix/misc' and 'topic/fix/hda' into for-linus · 6b425660
      由 Takashi Iwai 提交于
      6b425660
    • T
      ALSA: hda - Make the HP EliteBook 8530p use AD1884A model laptop · 25424831
      由 Travis Place 提交于 
      Added a QUIRK to patch_analog.c for the HP Elitebook 8530p
(IDs 0x103c:0x30e7) to use AD1884A model 'laptop' by default.
Playback and Capture confirmed working.
Signed-off-by: NTravis Place <wishie@wishie.net>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      25424831
    • T
      libata: revert convert-to-block-tagging patches · 8a8bc223
      由 Tejun Heo 提交于 
      This patch reverts the following three commits which convert libata to
use block layer tagging.

 43a49cbd
 e013e13b
 2fca5ccf

Although using block layer tagging is the right direction, due to the
tight coupling among tag number, data structure allocation and
hardware command slot allocation, libata doesn't work correctly with
the current conversion.

The biggest problem is guaranteeing that tag 0 is always used for
non-NCQ commands.  Due to the way blk-tag is implemented and how SCSI
starts and finishes requests, such guarantee can't be made.  I'm not
sure whether this would actually break any low level driver but it
doesn't look like a good idea to break such assumption given the
frailty of ATA controllers.

So, for the time being, keep using the old dumb in-libata qc
allocation.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Jens Axobe <jens.axboe@oracle.com>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8a8bc223
  5. 10 11月, 2008 13 次提交
  7. 09 11月, 2008 11 次提交
  9. 08 11月, 2008 9 次提交