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Date: Sat, 11 Sep 2004 16:19:46 -0700
From: Andrew Morton <akpm@osdl.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: linux-kernel@vger.kernel.org, mochel@digitalimplant.org
Subject: Re: swsusp: clean up reading
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Pavel Machek <pavel@ucw.cz> wrote:
>
>  -static void wait_io(void)
>  -{
>  -	while(atomic_read(&io_done))
>  -		io_schedule();
>  -}
>  -
>  -
>   static struct block_device * resume_bdev;
>   
> ...
> 
>  -	wait_io();
>  +	while (atomic_read(&io_done))
>  +		yield();

This doesn't seem to be much of an improvement, really.  It still runs the
risk that the caller might have SCHIED_FIFO policy and we end up in a
spinloop until I/O completion.

Why not stick a `struct completion' at bio->bi_private, do complete() in
the end_io handler and wait_for_completion() in the caller?

I'll add the current patch to -mm for now, thanks.