Re: [PATCH] mm: cleanup swap unused warning

From: Con Kolivas
Date: Wed May 10 2006 - 07:46:08 EST


On Wednesday 10 May 2006 21:38, Andrew Morton wrote:
> Con Kolivas <kernel@xxxxxxxxxxx> wrote:
> > Are there any users of swp_entry_t when CONFIG_SWAP is not defined?
>
> Well there shouldn't be. Making accesses to swp_entry_t.val fail to
> compile if !CONFIG_SWAP might be useful.
>
> > +/*
> > + * A swap entry has to fit into a "unsigned long", as
> > + * the entry is hidden in the "index" field of the
> > + * swapper address space.
> > + */
> > +#ifdef CONFIG_SWAP
> > typedef struct {
> > unsigned long val;
> > } swp_entry_t;
> > +#else
> > +typedef struct {
> > + unsigned long val;
> > +} swp_entry_t __attribute__((__unused__));
> > +#endif
>
> We have __attribute_used__, which hides a gcc oddity.

I tried that.

In file included from arch/i386/mm/pgtable.c:11:
include/linux/swap.h:82: warning: â__used__â attribute ignored
In file included from include/linux/suspend.h:8,
from init/do_mounts.c:7:
include/linux/swap.h:82: warning: â__used__â attribute ignored
In file included from arch/i386/mm/init.c:22:
include/linux/swap.h:82: warning: â__used__â attribute ignored
AS arch/i386/kernel/vsyscall-sysenter.o

etc..

and doesn't fix the warning in vmscan.c. __attribute_used__ is handled
differently by gcc4 it seems (this is 4.1.0)

--
-ck
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