linux-kernel - Re: [PATCH v4 1/3] dax: Add an enum for specifying dax wakup mode

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Date:   Mon, 26 Apr 2021 13:52:17 -0400
From:   Vivek Goyal <vgoyal@...hat.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     linux-fsdevel@...r.kernel.org, linux-nvdimm@...ts.01.org,
        dan.j.williams@...el.com, linux-kernel@...r.kernel.org,
        virtio-fs@...hat.com, miklos@...redi.hu, jack@...e.cz,
        slp@...hat.com, groug@...d.org
Subject: Re: [PATCH v4 1/3] dax: Add an enum for specifying dax wakup mode

On Mon, Apr 26, 2021 at 02:46:32PM +0100, Matthew Wilcox wrote:
> On Fri, Apr 23, 2021 at 09:07:21AM -0400, Vivek Goyal wrote:
> > +enum dax_wake_mode {
> > +	WAKE_NEXT,
> > +	WAKE_ALL,
> > +};
> 
> Why define them in this order when ...
> 
> > @@ -196,7 +207,7 @@ static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)
> >  	 * must be in the waitqueue and the following check will see them.
> >  	 */
> >  	if (waitqueue_active(wq))
> > -		__wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
> > +		__wake_up(wq, TASK_NORMAL, mode == WAKE_ALL ? 0 : 1, &key);
> 
> ... they're used like this?  This is almost as bad as
> 
> enum bool {
> 	true,
> 	false,
> };

Hi Matthew,

So you prefer that I should switch order of WAKE_NEXT and WAKE_ALL? 

enum dax_wake_mode {
	WAKE_ALL,
	WAKE_NEXT,
};


And then do following to wake task.

if (waitqueue_active(wq))
	__wake_up(wq, TASK_NORMAL, mode, &key);

I am fine with this if you like this better.

Or you are suggesting that don't introduce "enum dax_wake_mode" to
begin with.

Vivek