tracing: Remove bottle neck mutex in splicing from ring buffer

While profiling with trace-cmd, I found that the there was a global mutex being taken in the per-cpu splice code. This was slowing down the recording and causing more missed events than necessary.

By adding a ref count to the tracer, and preventing the tracer from changing when the ref count is non-zero (when a trace file is opened) we can remove the taking of the trace_types_lock mutex from the splice page and speed things up a bit.

git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
for-next

Head SHA1: d716ff71dd12bc6328f84a9ec1c3647daf01c827

Steven Rostedt (Red Hat) (2):
tracing: Add ref count to tracer for when they are being read by pipe
tracing: Remove taking of trace_types_lock in pipe files

----

 kernel/trace/trace.c | 126 ++++++++++++++++++---------------------------------
 kernel/trace/trace.h |   1 +
 2 files changed, 44 insertions(+), 83 deletions(-)