tracing: Fixes for v6.18

Fixes for tracing:

- Check for reader catching up in ring_buffer_map_get_reader()

If the reader catches up to the writer in the memory mapped ring buffer then calling rb_get_reader_page() will return NULL as there's no pages left. But this isn't checked for before calling rb_get_reader_page() and the return of NULL causes a warning.

If it is detected that the reader caught up to the writer, then simply exit the routine.

- Fix memory leak in histogram create_field_var()

The couple of the error paths in create_field_var() did not properly clean up what was allocated. Make sure everything is freed properly on error.

- Fix help message of tools latency_collector

The help message incorrectly stated that "-t" was the same as "--threads" whereas "--threads" is actually represented by "-e".

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

Head SHA1: 53afec2c8fb2a562222948cb1c2aac48598578c9

Steven Rostedt (1):
ring-buffer: Do not warn in ring_buffer_map_get_reader() when reader catches up

Zhang Chujun (1):
tracing/tools: Fix incorrcet short option in usage text for --threads

Zilin Guan (1):
tracing: Fix memory leaks in create_field_var()

----

 kernel/trace/ring_buffer.c                | 4 ++++
 kernel/trace/trace_events_hist.c          | 6 ++++--
 tools/tracing/latency/latency-collector.c | 2 +-
 3 files changed, 9 insertions(+), 3 deletions(-)