[PATCH v4] lib/spinlock_debug.c: prevent a recursive cycle in the debug code

From: Byungchul Park
Date: Wed Jan 27 2016 - 07:02:00 EST

changes form v3 to v4
- reuse a existing code as much as possible for preventing an infinite
recursive cycle.

changes from v2 to v3
- avoid printk() only in case of lockup suspected, not real lockup in
which case it does not help at all.
- consider not only console_sem.lock but also logbuf_lock which is used
by printk().

changes from v1 to v2
- only change comment and commit message esp. replacing "deadlock" with
"infinite recursive cycle", since it is not an actual deadlock.