On Mon, Sep 03, 2012 at 02:40:39PM +0200, Marc Kleine-Budde wrote: > On 08/25/2012 12:01 AM, Fabio Baltieri wrote: > > Hello Kurt, > > > > On Fri, Aug 24, 2012 at 02:42:48PM +0200, Kurt Van Dijck wrote: > >> On Fri, Aug 24, 2012 at 01:28:16PM +0200, Marc Kleine-Budde wrote: > >>> On 08/24/2012 07:10 AM, Kurt Van Dijck wrote: > >>>> Hello, > >>>> > >>>> I find the CAN led triggers an interesting thing. > >>>> > >>>> And then, this scenario fell crossed my mind: > >>>> Imagine I do: > >>>> [insert CAN device: can0] > >>>> $ ip link set can0 name helga > >>>> [insert another CAN device: again 'can0'] > >>>> > >>>> Registering 'can0-tx' led trigger will fail for the second CAN device, > >>>> since that led trigger name is already reserved for CAN device 'helga'. > >>> Good point. > > > > Yep, thanks for pointing that out! > > > > Interface renaming was something I considered when I first wrote the > > code and I had the mac80211-led driver in mind, as that driver uses the > > phy name and not the netdev one for its triggers. > > > > The reason why I did not care that much in the end is that on SoC based > > systems trigger-led association is made at probe time, based on data > > either from platform_data or devicetree, so I imagined that once the > > kernel is ported to the board and default triggers are set correctly at > > boot time, the userspace is free to rename CAN interfaces and nobody > > should notice... :^) > > > > The thing I did not consider are hot-plug interfaces mixed with > > renaming, such as in the case you pointed out - it's probably not really > > common but still possible. > > > >>>> I'm not sure how to fix such. > >>>> If 'rx' & 'tx' may be combined, reusing the netdev name may be possible? > >>>> Just wild thinking ... > >>> > >>> I think the device's name (not netdev) is unique in the system and > >>> cannot be changed. > >> > >> but may contain several netdev's ... > > > > Ouch. > > The net->ifindex is unique. But it's only an integer. Usually can0 has a > ifindex != 0, so a simple can%d is contra productive here. > > Some pointers to related code: > http://lxr.free-electrons.com/source/drivers/base/core.c#L1847 > http://lxr.free-electrons.com/source/drivers/base/core.c#L73 > http://lxr.free-electrons.com/source/include/linux/device.h#L695 > > comments?
a very recent idea: something with netdevice notifiers and NETDEV_CHANGENAME ... http://lxr.free-electrons.com/source/net/core/dev.c#L1030 you could: rename the trigger, or if we think it's usefull, block the netdev rename when its triggers are in use. Kurt -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
