linux-kernel - Re: [PATCH 2/3] vmevent: Factor vmevent_match_attr() out of vmevent

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Message-ID: <20121012222141.GA15629@lizard>
Date:	Fri, 12 Oct 2012 15:21:42 -0700
From:	Anton Vorontsov <anton.vorontsov@...aro.org>
To:	Pekka Enberg <penberg@...nel.org>
Cc:	John Stultz <john.stultz@...aro.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, linaro-kernel@...ts.linaro.org,
	patches@...aro.org
Subject: Re: [PATCH 2/3] vmevent: Factor vmevent_match_attr() out of
 vmevent_match()

On Fri, Oct 12, 2012 at 03:37:43PM +0300, Pekka Enberg wrote:
[...]
> > +static bool vmevent_match_attr(struct vmevent_attr *attr, u64 value)
> > +{
> > +       u32 state = attr->state;
> > +       bool attr_lt = state & VMEVENT_ATTR_STATE_VALUE_LT;
> > +       bool attr_gt = state & VMEVENT_ATTR_STATE_VALUE_GT;
> > +       bool attr_eq = state & VMEVENT_ATTR_STATE_VALUE_EQ;
> > +       bool edge = state & VMEVENT_ATTR_STATE_EDGE_TRIGGER;
> > +       u32 was_lt_mask = VMEVENT_ATTR_STATE_VALUE_WAS_LT;
> > +       u32 was_gt_mask = VMEVENT_ATTR_STATE_VALUE_WAS_GT;
> > +       bool lt = value < attr->value;
> > +       bool gt = value > attr->value;
> > +       bool eq = value == attr->value;
> > +       bool was_lt = state & was_lt_mask;
> > +       bool was_gt = state & was_gt_mask;
> 
> [snip]
> 
> So I merged this patch but vmevent_match_attr() is still too ugly for
> words. It really could use some serious cleanups.

Thanks a lot for merging these cleanups!

Yes, the patch wasn't meant to simplify the matching logic, but just to
let us use the function in other places.

I once started converting the function into table-based approach, but the
code started growing, and I abandoned the idea for now. I might resume the
work just for the fun of it, but the code will be larger than this ad-hoc
function, althouh surely it will be more generic and understandable.

But let's solve primary problems with the vmevent first. :-)

Thanks,
Anton.
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