We observed the crash point count going negative in cases where the
crash point is hit multiple times before the check of "count == 0" is
done.  Because of this we never call lkdtm_do_action().  This patch just
adds a spinlock to protect count.
Reported-by: NTapan Dhimant <tdhimant@akamai.com>
Signed-off-by: NJosh Hunt <johunt@akamai.com>
Acked-by: NAnkita Garg <ankita@in.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>