Re: page_launder() bug

Rusty Russell
2001-05-09T02:29:00Z

In message <15094.10942.592911.70443@pizda.ninka.net> you write:
>
> Jonathan Morton writes:
> > >- page_count(page) == (1 + !!page->buffers));
> >
> > Two inversions in a row?
>
> It is the most straightforward way to make a '1' or '0'
> integer from the NULL state of a pointer.

Overall, I'd have to say that this:

- dead_swap_page =
- (PageSwapCache(page) &&
- page_count(page) == (1 + !!page->buffers));
-

Is nicer as:

int dead_swap_page = 0;

if (PageSwapCache(page)
&& page_count(page) == (page->buffers ? 1 : 2))
dead_swap_page = 1;

After all, the second is what the code *means* (1 and 2 are magic
numbers).

That said, anyone who doesn't understand the former should probably
get some more C experience before commenting on others' code...

Rusty.
--
Premature optmztion is rt of all evl. --DK