Re: [PATCH 2/2] lockdep: check that no locks held at freeze time

[Pavel Machek]

On Fri 2013-05-03 14:04:10, Colin Cross wrote:
> From: Mandeep Singh Baines <msb@xxxxxxxxxxxx>
> 
> 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
-- 
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