lkml.org 
[lkml]   [2009]   [Jul]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RESEND PATCH 01/11] kernel:lockdep:print the shortest dependency chain if finding a circle
From
Date
On Mon, 2009-07-13 at 09:01 +0200, Ingo Molnar wrote:
>
> It's a nice byproduct, beyond the primary advantage of not being a
> stack based recursion check.
>
> I think this patch-set is great, and there's just one more step
> needed to make it round: it would be nice to remove the limitation
> of maximum number of locks held per task. (MAX_LOCK_DEPTH)
>
> The way we could do it is to split out this bit of struct task:
>
> #ifdef CONFIG_LOCKDEP
> # define MAX_LOCK_DEPTH 48UL
> u64 curr_chain_key;
> int lockdep_depth;
> unsigned int lockdep_recursion;
> struct held_lock held_locks[MAX_LOCK_DEPTH];
> gfp_t lockdep_reclaim_gfp;
> #endif
>
> into a separate 'struct lockdep_state' structure, and allocate it
> dynamically during fork with a initial pre-set size of say 64 locks
> depth. If we hit that limit, we'd double the allocation threshold,
> which would cause a larger structure to be allocated for all newly
> allocated tasks.

Right, except allocating stuff while in the middle of lockdep is very
hard since it involves taking more locks :-)

I've tried it several times but never quite managed it in a way that I
felt comfortable with.

It would require having a reserve and serializing over that reserve.



\
 
 \ /
  Last update: 2009-07-13 11:17    [from the cache]
©2003-2011 Jasper Spaans