tracing: Fixes for 7.1

tracing fixes for v7.1:

- Avoid NULL return from hist_field_name()

The function hist_field_name() is directly passed to a strcat() which does not handle "NULL" characters. Return a zero length string when size is greater than the limit.

This is used only to output already created histograms and no field currently is greater than the limit. But it should still not return NULL.

- Do not call map->ops->elt_free() on allocation failure

When elt_alloc() fails, it should not call the map->ops->elt_free() function if it exists, as that function may not be able to handle the free on allocation failures. The ->elt_free() should only be called when elt_alloc() succeeds.

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

Head SHA1: 8f0f5c4fb9df0e19a341e0c6ed8dc4fda9124f03

David Carlier (1):
tracing: Avoid NULL return from hist_field_name() on truncation

Masami Hiramatsu (Google) (1):

      tracing: Do not call map->ops->elt_free() if elt_alloc() fails

----

 kernel/trace/trace_events_hist.c |  6 ++----
 kernel/trace/tracing_map.c       | 17 +++++++++++++----
 2 files changed, 15 insertions(+), 8 deletions(-)