On Sat, Dec 10, 2011 at 05:08:21PM +0000, Jonathan Cameron wrote:
> ...
> >
> >> --- /dev/null
> >> +++ b/drivers/staging/iio/inkern.c
> >> @@ -0,0 +1,21 @@
> >> +/* The industrial I/O core in kernel channel mapping
> >> + *
> >> + * Copyright (c) 2011 Jonathan Cameron
> >> + *
> >> + * This program is free software; you can redistribute it and/or modify it
> >> + * under the terms of the GNU General Public License version 2 as published by
> >> + * the Free Software Foundation.
> >> + */
> >> +#include "inkern.h"
> >> +#include <linux/err.h>
> >> +#include <linux/export.h>
> >> +
> >> +LIST_HEAD(iio_map_list);
> >> +EXPORT_SYMBOL_GPL(iio_map_list);
> >> +void iio_map_array_register(struct iio_map *map, int nummaps)
> >> +{
> >> + int i;
> >> + for (i = 0; i < nummaps; i++)
> >> + list_add(&map[i].l, &iio_map_list);
> >> +}
> >> +EXPORT_SYMBOL(iio_map_array_register);
> >
> > No _GPL here?
> oops
> >
> > If you have a register function, why do you need to export the list
> > symbol as well? Shouldn't you have accessor functions for the whole
> > list? And what is this list for?
>
> The issue here is where the access functions reside.
>
> The list registration stuff has to be built in (now optionally!) so that
> it can be filled from board files if appropriate.
>
> The list is then used by the iio-core in response to requests from
> client drivers that want to get data from iio devices. Short of
> supplying access functions that are effectively the equivalent of
> the standard list access functions I can't really see how else to
> avoid exporting this.
So why is this separate from the iio-core code?
And how are you guaranteing that anyone walking the list is doing so in
a "safe" manner? What's to keep an entry from being removed while some
random kernel code is walking it?
Hint, don't allow direct access to this list, if you do so, you are in
for a world of hurt...
> I'd welcome any suggestions on this!
>
> As for the other issues. I've added another kernel symbol (boolean)
> as a top level for iio with the core underneath. That means that
> this bit is no longer always built in. An additional header and
> source file now contain the elements that were defined in inkern.h
> and implemented in industrialio-core.c (inkern-consumer.h/.c).
> Will repost for review once we've addressed this exported list question!
Thanks for changing this.
greg k-h
--
To unsubscribe from this list: send the line "unsubscribe linux-iio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
