[RFC v4] Kernel access to ftrace instances.

[Divya Indi <divya.indi@oracle.com>]

Hi,

Please review the patches that follow -

[PATCH 1/5] tracing: Declare newly exported APIs in include/linux/trace.h
[PATCH 2/5] tracing: Verify if trace array exists before destroying it.
[PATCH 3/5] tracing: Adding NULL checks
[PATCH 4/5] tracing: Adding new functions for kernel access to Ftrace instances.
[PATCH 5/5] tracing: Sample module to demonstrate kernel access to Ftrace instances.

This patchset addresses the feedback recieved for v3.

Changes from v3 include -

1) trace_array_get_by_name() replaces trace_array_lookup and 
with its new implementation we no longer need to export
trace_array_create().

If a trace array with given name exists, this func returns a pointer
to this trace array (Previously, trace_array_lookup()). 
If does not exist, create a new trace array (Previously done by trace_array_create()).

2) A new trace array will always have ref ctr = 1 on creation.
Destroying a trace array will require its ref ctr to be 1.

3) trace_array_set_clr_event(): Uses boolean instead of 0/1 to enable/disable
events to a trace array. 

4) Sample module reflects the above changes. It is now part of the same patch-set.

Thanks,
Divya