Messages in this thread | | | Date | Fri, 20 Oct 2017 08:34:36 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [RESEND PATCH 1/3] completion: Add support for initializing completion with lockdep_map |
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On Thu, 19 Oct 2017, Bart Van Assche wrote: > On Wed, 2017-10-18 at 18:38 +0900, Byungchul Park wrote: > > Sometimes, we want to initialize completions with sparate lockdep maps > > to assign lock classes under control. For example, the workqueue code > > manages lockdep maps, as it can classify lockdep maps properly. > > Provided a function for that purpose. > > > > Signed-off-by: Byungchul Park <byungchul.park@lge.com> > > --- > > include/linux/completion.h | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/include/linux/completion.h b/include/linux/completion.h > > index cae5400..182d56e 100644 > > --- a/include/linux/completion.h > > +++ b/include/linux/completion.h > > @@ -49,6 +49,13 @@ static inline void complete_release_commit(struct completion *x) > > lock_commit_crosslock((struct lockdep_map *)&x->map); > > } > > > > +#define init_completion_with_map(x, m) \ > > +do { \ > > + lockdep_init_map_crosslock((struct lockdep_map *)&(x)->map, \ > > + (m)->name, (m)->key, 0); \ > > + __init_completion(x); \ > > +} while (0) > > Are there any completion objects for which the cross-release checking is > useful?
All of them by definition.
> Are there any wait_for_completion() callers that hold a mutex or > other locking object?
Yes, there are also cross completion dependencies. There have been such bugs and I expect more to be unearthed.
I really have to ask what your motiviation is to fight the lockdep coverage of synchronization objects tooth and nail?
Thanks,
tglx
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