tracing: Fixes for v7.2

tracing fixes for 7.2:

- Reset dropped_count in mmio_reset_data()

When mmio_reset_data() is called, it does not reset the dropped_count so that subsequent runs will have incorrect reporting.

- Add NULL check for mmio_trace_array in logging functions

The functions __trace_mmiotrace_rw() and __trace_mmiotrace_map() may have the 'tr' variable passed to it as NULL. But they both dereference it without checking if it is NULL first.

- Check return value of __register_event() in trace_module_add_events()

If __register_event() fails, the call after it (__add_event_to_tracers()) will create a file for it. If the module fails to load and its memory is freed, the file will still point to it and it will not be removed as the registering of the event did not complete. Only call __add_event_to_tracers() if the __register_event() was successful.

- Fix false positive match in regex_match_full()

The regex full matching uses a strncmp() to test against the match string and the value. It should not match if value is a prefix of the string to match. Check to make sure the length of the strings match before comparing.

- Fix reader page read offset for remote buffers

A page swapped in by __rb_get_reader_page_from_remote() retains its stale read offset, causing subsequent reads to skip events or read past valid data.

git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace/fixes

Head SHA1: 78cd56c2a9d2e8da763cea3b06b636266ca66911

Masami Hiramatsu (Google) (4):
tracing/mmiotrace: Reset dropped_count in mmio_reset_data() tracing/mmiotrace: Add NULL check for mmio_trace_array in logging functions
tracing: Check return value of __register_event() in trace_module_add_events() tracing/filters: Fix false positive match in regex_match_full()

Vincent Donnefort (1):
ring-buffer: Fix reader page read offset for remote buffers

----

 kernel/trace/ring_buffer.c         |  1 +
 kernel/trace/trace_events.c        |  4 ++--
 kernel/trace/trace_events_filter.c |  3 +++
 kernel/trace/trace_mmiotrace.c     | 13 +++++++++++--
 4 files changed, 17 insertions(+), 4 deletions(-)