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SubjectRe: [PATCH 2/2] lockdep: check that no locks held at freeze time
On Fri 2013-05-03 14:04:10, Colin Cross wrote:
> From: Mandeep Singh Baines <msb@chromium.org>
>
> We shouldn't try_to_freeze if locks are held. Holding a lock can cause a
> deadlock if the lock is later acquired in the suspend or hibernate path
> (e.g. by dpm). Holding a lock can also cause a deadlock in the case of
> cgroup_freezer if a lock is held inside a frozen cgroup that is later
> acquired by a process outside that group.

Ok, but this does not explain why

> --- a/include/linux/debug_locks.h
> +++ b/include/linux/debug_locks.h
> @@ -51,7 +51,7 @@ struct task_struct;
> extern void debug_show_all_locks(void);
> extern void debug_show_held_locks(struct task_struct *task);
> extern void debug_check_no_locks_freed(const void *from, unsigned long len);
> -extern void debug_check_no_locks_held(struct task_struct *task);
> +extern void debug_check_no_locks_held(void);
> #else
> static inline void debug_show_all_locks(void)
> {

Removing task_struct argument from those functions is good idea?

> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -835,7 +835,7 @@ void do_exit(long code)
> /*
> * Make sure we are holding no locks:
> */
> - debug_check_no_locks_held(tsk);
> + debug_check_no_locks_held();

Is task guaranteed == current?

Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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