Re: what is spinlock depth

[Jiri Slaby <jirislaby@gmail.com>]

On 01/31/2011 09:27 PM, Sri Ram Vemulpali wrote:
> Hi all,
> 
> I am reading spinlock code and looking at struct raw_spinlock. I found
> struct lockdep_map as member.
> which is defined as
> 
> struct lockdep_map {
>        struct lock_class_key           *key;
>        struct lock_class               *class_cache[NR_LOCKDEP_CACHING_CLASSES];
>        const char                      *name;
> #ifdef CONFIG_LOCK_STAT
>        int                             cpu;
>       unsigned long                   ip;
> #endif
> };
> 
> Can anyone help me explain, how this struct helps the spinlock. Why do
> we need lockdepth.

It's not dep-th, but dep-endency. It's a debugging technique to
dynamically check for locking correctness. See more details in
Documentation/lockdep-design.txt.

-- 
js