[GIT PULL] ring-buffer: Updates for 7.2

[Steven Rostedt]

Linus,

ring-buffer: Updates for v7.2:

- Do not invalidate entire buffer for invalid sub-buffers

  For the persistent ring buffer, if one sub-buffer is found to be invalid,
  it invalidates the entire per CPU ring buffer. This can lose a lot of
  valuable data if there's some corruption with the writes to the buffer not
  syncing properly on a hard crash. Instead, if a sub-buffer is found to be
  invalid, simply zero it out and mark it for "missed events".

  When the persistent ring buffer is read and a sub-buffer that was cleared
  due to being invalid on boot up is discovered, the output will show
  "[LOST EVENTS]" to let the user know that events were missing at that
  location. Displaying the events from valid buffers can still be useful.

- Add a test to be able to test corrupted sub-buffers

  If a persistent ring buffer is created as "ptracingtest" and the new config
  that adds the test is enabled, when a panic happens, the kernel will
  randomly corrupt one of the per CPU ring buffers. On boot up, the
  sub-buffers with the corruption should be cleared and flagged. When
  reading this buffer, the missed events should should [LOST EVENTS].

- Add commit number in the sub-buffer meta debug info

  The commit is used to know the content of a meta page. Add it to the
  buffer_meta file that is shown for each per CPU buffer.

- Clean up the persistent ring buffer validation code

  Add some helper functions and make variable names more consistent.


Please pull the latest trace-ring-buffer-v7.2 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace-ring-buffer-v7.2

Tag SHA1: eec08f17230e4b945157bba627e71a542e291784
Head SHA1: 4e8729e6598ba0d10021dbf48b308cd53a06bbc4


Masami Hiramatsu (Google) (6):
      ring-buffer: Skip invalid sub-buffers when validating persistent ring buffer
      ring-buffer: Skip invalid sub-buffers when rewinding persistent ring buffer
      ring-buffer: Add persistent ring buffer invalid-page inject test
      ring-buffer: Show commit numbers in buffer_meta file
      ring-buffer: Cleanup persistent ring buffer validation
      ring-buffer: Cleanup buffer_data_page related code

Steven Rostedt (4):
      ring-buffer: Have dropped subbuffers be persistent across reboots
      ring-buffer: Show persistent buffer dropped events in trace file
      ring-buffer: Show persistent buffer dropped events in trace_pipe file
      ring-buffer: Better comment the use of RB_MISSED_EVENTS

----
 include/linux/ring_buffer.h |   1 +
 kernel/trace/Kconfig        |  34 +++
 kernel/trace/ring_buffer.c  | 557 ++++++++++++++++++++++++++++++--------------
 kernel/trace/trace.c        |   4 +
 4 files changed, 416 insertions(+), 180 deletions(-)
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