Re: [PATCH] writeback: fix hung_task alarm when sync block

[Fengguang Wu <fengguang.wu@intel.com>]

> >> @@ -1311,7 +1312,12 @@ void writeback_inodes_sb_nr(struct super_block *sb,
> >>  
> >>  	WARN_ON(!rwsem_is_locked(&sb->s_umount));
> >>  	bdi_queue_work(sb->s_bdi, &work);
> >> -	wait_for_completion(&done);
> >> +	hangcheck = sysctl_hung_task_timeout_secs;
> >> +	if (hangcheck)
> >
> >The hangcheck variable looks redundant.
> 
> if sysctl_hung_task_timeout_secs is equal to ZERO, it means infinite
> timeout -- no checking done. So I think wait_for_completion_timeout 
> makes no sense this time.

I mean, you can test sysctl_hung_task_timeout_secs directly?
It's a one shot test anyway.

> >> +		while (!wait_for_completion_timeout(&done, HZ/2))
> >> +			;
> >> +	else
> >> +		wait_for_completion(&done);
> >>  }
> >>  EXPORT_SYMBOL(writeback_inodes_sb_nr);
> >>  
> >> -- 
> >> 1.7.9.5