On Sat, Apr 04, 2015 at 06:59:58PM +0300, Dan Carpenter wrote: > This is a clever Coccinelle check. :) > > On Sat, Apr 04, 2015 at 04:59:30PM +0200, Julia Lawall wrote: > > Put NULL test on the result of the previous call instead on one of its > > arguments. A simplified version of the semantic match that finds this > > problem is as follows (http://coccinelle.lip6.fr/): > > > > // <smpl> > > r@ > > expression *e1; > > expression *e2; > > identifier f; > > statement S1,S2; > > @@ > > > > e1 = f(...,e2,...); > > ( > > if (e1 == NULL || ...) S1 else S2 > > | > > *if (e2 == NULL || ...) S1 else S2 > > ) > > // </smpl> > > > > Signed-off-by: Julia Lawall <Julia.Lawall@xxxxxxx> > > > > --- > > drivers/staging/emxx_udc/emxx_udc.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/staging/emxx_udc/emxx_udc.c b/drivers/staging/emxx_udc/emxx_udc.c > > index fbf82bc..7de1e9e 100644 > > --- a/drivers/staging/emxx_udc/emxx_udc.c > > +++ b/drivers/staging/emxx_udc/emxx_udc.c > > @@ -2998,7 +2998,7 @@ static void nbu2ss_ep_fifo_flush(struct usb_ep *_ep) > > } > > > > ep = container_of(_ep, struct nbu2ss_ep, ep); > > - if (!_ep) { > > + if (!ep) { > > pr_err("udc: %s, bad ep\n", __func__); > > return; > > The better thing to do here is to remove the condition. container_of() > takes an pointer and subtracts an offset so testing the return value > is normally meaningless. > > Sometimes (and in this case) the offset is zero. In that situation it > might make sense to check the return value but it's an ugly thing to > do because if we re-order the nbu2ss_ep struct layout so "ep" isn't the > first member then it breaks. > > In this case we already verified that "_ep" is non-NULL so the check > isn't needed. This will teach me to read ahead in an email thread... :) -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
