Am 19.07.2016 um 17:59 schrieb Boris Brezillon: > On Tue, 19 Jul 2016 17:44:48 +0200 > Richard Weinberger <[email protected]> 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 <[email protected]> >>> --- >>> 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 ;-).
When this really just triggers a NULL-pointer exception, we don't need a BUG_ON or WARN_ON at all since the kernel can tell anyway what went wrong. >From the patch description I thought it is a more cryptic problem... Thanks, //richard
