Re: check && lockdep_no_validate (Was: lockdep: Introduce wait-typechecks)
From: Peter Zijlstra
Date: Thu Jan 16 2014 - 13:10:02 EST
On Thu, Jan 16, 2014 at 06:43:48PM +0100, Oleg Nesterov wrote:
> But with or without this change the following code
> static DEFINE_MUTEX(m1);
> static DEFINE_MUTEX(mx);
> // m1 -> mx
> // mx -> m1 ; should trigger the warning ???
> doesn't trigger the warning too. This is correct because
> lockdep_set_novalidate_class() means, well, no-validate.
> The question is: do we really want to avoid all validations?
> Why lockdep_set_novalidate_class() was added? Unlees I missed
> something the problem is that (say) __driver_attach() can take
> the "same" lock twice, drivers/base/ lacks annotations.
Indeed, the driver model locking always slips my mind but yes its
creative. Alan Stern seems to have a good grasp on it though.
> Perhaps we should change the meaning of lockdep_set_novalidate_class?
> (perhaps with rename). What do you think about the patch below?
> With this patch __lockdep_no_validate__ means "automatically nested",
Yes, I suppose that might work, it would allow some validation.
> although I have to remind I can hardly understand the code I am
> trying to change ;)
You don't seem to be doing too badly ;-)
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