Re: [PATCH 1/2] mtd: nand: BUG_ON in case of no select_chip and cmd_ctrl

Boris Brezillon
2016-07-19T15:59:18Z

On Tue, 19 Jul 2016 17:44:48 +0200
Richard Weinberger <richard@nod.at> wrote:

> Am 19.07.2016 um 17:41 schrieb Andrey Smirnov:
> > If no user specified chip->select_chip() function is provided, code in
> > nand_base.c will automatically set this hook to nand_select_chip(),
> > which in turn depends on chip->cmd_ctrl() hook being valid. Not
> > providing both of those functions in NAND controller driver (for example
> > by mistake) will result in a bit cryptic segfault. Replace it with
> > explicit BUG_ON statement so it would be obvious what went wrong.
> >
> > Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> > ---
> > drivers/mtd/nand/nand_base.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> > index ce7b2ca..57043a6 100644
> > --- a/drivers/mtd/nand/nand_base.c
> > +++ b/drivers/mtd/nand/nand_base.c
> > @@ -3128,8 +3128,10 @@ static void nand_set_defaults(struct nand_chip *chip, int busw)
> > if (chip->waitfunc == NULL)
> > chip->waitfunc = nand_wait;
> >
> > - if (!chip->select_chip)
> > + if (!chip->select_chip) {
> > + BUG_ON(!chip->cmd_ctrl);
>
> Please don't add new BUG_ON() calls. WARN_ON() is good enough to raise the driver developer's
> attention and won't kill the machine.

Not sure a BUG_ON() is worst than a NULL-pointer exception ;-).