Re: [PATCH v5] lib/spinlock_debug.c: prevent a recursive cycle in the debug code

From: Sergey Senozhatsky
Date: Sun Jan 31 2016 - 21:12:11 EST

On (02/01/16 10:45), Byungchul Park wrote:
> But avoiding an unnecessary recursive cycle is better than panic(). What I handled
> in this patch is the warning case which causes unnecessary lockup and don't need to
> happen.


correct, that was one of the reasons why I proposed to
return back to discussion. it's a bit hard to tell if
we have any chance to survive a "lockup suspected"
spin_dump() recursion; even if we have one, it's a race
spin_unlock on CPUA vs. stack overflow on CPUB. we can
be more certain with ->magic mismatch, for example, but
"lockup suspected" is tricky.