tracing: More fixes for v7.2

tracing fixes for 7.2:

- Fix use-after-free in user_event_mm_dup()

When the enabler is removed from the link list, it is freed immediately. But it is protected via RCU and needs to be freed after an RCU grace period. Use queue_rcu_work() so that the event_mutex can also be taken as user_event_put() takes the mutex on the last reference is released.

- Free type string in error path of parse_synth_field()

There's an error path in parse_synth_field() where the allocated type string is not freed.

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

Head SHA1: 05074bb90af94f2acbbc8f8ffaa507f914c273c8

Michael Bommarito (1):
tracing/user_events: Fix use-after-free in user_event_mm_dup()

Yu Peng (1):
tracing/synthetic: Free type string on error path

----

 kernel/trace/trace_events_synth.c |  4 +++-
 kernel/trace/trace_events_user.c  | 39 ++++++++++++++++++++++++++++++++-------
 2 files changed, 35 insertions(+), 8 deletions(-)