Re: [PATCH V9 3/6] mm: frontswap: core frontswap functionality

[Andrew Morton <akpm@google.com>]

On Tue, 13 Sep 2011 15:40:36 -0500
Seth Jennings <sjenning@linux.vnet.ibm.com> wrote:

> Hey Dan,
> 
> I get the following compile warnings:
> 
> mm/frontswap.c: In function ‘init_frontswap’:
> mm/frontswap.c:264:5: warning: passing argument 4 of ‘debugfs_create_size_t’ from incompatible pointer type
> include/linux/debugfs.h:68:16: note: expected ‘size_t *’ but argument is of type ‘long unsigned int *’
> mm/frontswap.c:266:5: warning: passing argument 4 of ‘debugfs_create_size_t’ from incompatible pointer type
> include/linux/debugfs.h:68:16: note: expected ‘size_t *’ but argument is of type ‘long unsigned int *’
> mm/frontswap.c:268:5: warning: passing argument 4 of ‘debugfs_create_size_t’ from incompatible pointer type
> include/linux/debugfs.h:68:16: note: expected ‘size_t *’ but argument is of type ‘long unsigned int *’
> mm/frontswap.c:270:5: warning: passing argument 4 of ‘debugfs_create_size_t’ from incompatible pointer type
> include/linux/debugfs.h:68:16: note: expected ‘size_t *’ but argument is of type ‘long unsigned int *’
> 
> size_t is platform dependent but is generally "unsigned int"
> for 32-bit and "unsigned long" for 64-bit.
> 
> I think just typecasting these to size_t * would fix it.

That's very risky.

> On 09/13/2011 12:40 PM, Dan Magenheimer wrote:
> > +#ifdef CONFIG_DEBUG_FS
> > +	struct dentry *root = debugfs_create_dir("frontswap", NULL);
> > +	if (root == NULL)
> > +		return -ENXIO;
> > +	debugfs_create_size_t("gets", S_IRUGO,
> > +				root, &frontswap_gets);
> > +	debugfs_create_size_t("succ_puts", S_IRUGO,
> > +				root, &frontswap_succ_puts);
> > +	debugfs_create_size_t("puts", S_IRUGO,
> > +				root, &frontswap_failed_puts);
> > +	debugfs_create_size_t("invalidates", S_IRUGO,
> > +				root, &frontswap_invalidates);
> > +#endif

Make them u32 and use debugfs_create_x32(), perhaps.  Or create
debugfs_create_ulong().