[GIT PULL] ring-buffer: Updates for 7.3

Linus,

ring-buffer updates for 7.3:

- Remove unneeded semicolon

  A macro ended with a semicolon that wasn't needed.

- Fix freeing cpu_buffer extra subbuffer with order greater than zero

  When the cpu_buffer was being freed, its "free" page, was using
  free_page() to free it when it could be more than one page.

- Hold the cpu_buffer lock when resizing the subbuffer

  The freeing of the "free" page of the cpu_buffer was done without locking.
  The order of the data was being saved and then the "free" page was set to
  NULL. But there is a race that the "free" page could have been updated
  between those two operations. Add locking around it to prevent the race.

- Save the order of the data along with the data in the free page

  The cpu_buffer would store just the data portion of the subbuffer page in
  its descriptor. But it did not store the order of the data pages. The order
  was being saved in the global buffer descriptor. But this leads to races.

  Have the cpu_buffer save the subbuf data along with its metadata (which
  includes the order of the page) to make sure when it frees it, it frees
  the correct order along with it.

- Remove the subbuf_size and use the order directly when needed

  Having a size field for the size of the subbufer along with its order
  allowed for races to have them get out of sync. Remove the subbuf_size and
  use the order from the subbuf meta data directly under locks.

  Use the subbuf_order for other calculations in the ring buffer.

- Remove the useless "cpus" field of trace_buffer

  The code has been restructured and the "cpus" field is no longer used.
  Remove it.

- Remove the "mapped" field of the ring buffer and use a helper function instead.

  The "mapped" field has become a bit overused and made the code come
  complex in using a counter for what is denoted as being mapped or not.
  There are other fields that are set when the ring buffer is considered
  mapped. Add a helper function to check those fields and use that instead
  of keeping track of a counter.


Please pull the latest trace-ringbuffer-v7.3 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace-ringbuffer-v7.3

Tag SHA1: ff54701599a2c7d5155e1180ecac245a6a8d40c7
Head SHA1: 8b502bf6eb3da15f4b954ad3632335ff10ed746a


Julia Lawall (1):
      ring-buffer: drop unneeded semicolon

Vincent Donnefort (8):
      ring-buffer: Free cpu_buffer::free_page with subbuf_order
      ring-buffer: Hold cpu_buffer::lock when resizing a subbuf
      ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page
      ring-buffer: Fix subbuf resize race with ring buffer readers
      ring-buffer: Fix subbuf resize race with ring_buffer_alloc_read_page()
      ring-buffer: Dynamically calculate max_data_size
      ring-buffer: Remove trace_buffer::cpus
      ring-buffer: Remove ring_buffer_per_cpu::mapped

----
 kernel/trace/ring_buffer.c | 272 ++++++++++++++++++++++++++-------------------
 1 file changed, 160 insertions(+), 112 deletions(-)
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