On Fri, Jan 15, 2021 at 04:07:23PM -0800, Jakub Kicinski wrote: > On Fri, 15 Jan 2021 15:30:35 +0100 Oleksij Rempel wrote: > > Since 20dd3850bcf8 ("can: Speed up CAN frame receiption by using > > ml_priv") the CAN framework uses per device specific data in the AF_CAN > > protocol. For this purpose the struct net_device->ml_priv is used. Later > > the ml_priv usage in CAN was extended for other users, one of them being > > CAN_J1939. > > > > Later in the kernel ml_priv was converted to an union, used by other > > drivers. E.g. the tun driver started storing it's stats pointer. > > > > Since tun devices can claim to be a CAN device, CAN specific protocols > > will wrongly interpret this pointer, which will cause system crashes. > > Mostly this issue is visible in the CAN_J1939 stack. > > > > To fix this issue, we request a dedicated CAN pointer within the > > net_device struct. > > No strong objection, others already added their pointers, but > I wonder if we can't save those couple of bytes by adding a > ml_priv_type, to check instead of dev->type? And leave it 0 > for drivers using stats? Sounds good. If we want to save even more bytes, it might be possible, to move the wireless and wpan pointers to ml_priv. struct wireless_dev *ieee80211_ptr; struct wpan_dev *ieee802154_ptr; > That way other device types which are limited by all being > ARPHDR_ETHER can start using ml_priv as well? > > > +#if IS_ENABLED(CONFIG_CAN) > > + struct can_ml_priv *can; > > +#endif > > Perhaps put it next to all the _ptr fields? Makes sense. Oleksij will resping the series. regards, Marc -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
Attachment:
signature.asc
Description: PGP signature