Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock()

Peter Zijlstra
2008-08-04T14:20:00Z

On Mon, 2008-08-04 at 07:07 -0700, Roland Dreier wrote:
> > NOTE: we're still bound to the MAX_LOCK_DEPTH (48) limit.
>
> A) It is probably a good idea to put this in a comment somewhere near
> where spin_lock_nest_lock() is declared.

Its not particular to this annotation - its true for anything lockdep.

> B) It is probably a good idea to write that comment in such a way that
> dumb people like me understand what the limit is. The sentence I
> quoted above is too telegraphic for me to get. Is the point that no
> more than 48 spinlocks can be held at once, even if the inner locks
> are protected by some top level lock? Or do you mean something else?

No more than 48 locks (mutexes, rwlocks, spinlock, RCU, everything
covered by lockdep) held by any one code-path; including nested
interrupt contexts.