Re: [PATCH] mm: vmscan: handle any negative return value fromscan_objects

From: Dave Chinner
Date: Thu May 16 2013 - 07:52:52 EST

On Thu, May 16, 2013 at 10:42:16AM +0200, Oskar Andero wrote:
> The shrinkers must return -1 to indicate that it is busy. Instead, treat
> any negative value as busy.

Why? The API defines return condition for aborting a scan and gives
a specific value for doing that. i.e. explain why should change the
API to over-specify the 'abort scan" return value like this.

FWIW, using "any" negative number for "abort scan" is a bad API
design decision. It means that in future we can't introduce
different negative return values in the API if we have a new to.
i.e. each specific negative return value needs to have the potential
for defining a different behaviour.

So if any change needs to be made, it is to change the -1 return
value to an enum and have the shrinkers return that enum when they
want an abort.

Dave Chinner
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