On 8/30/19 8:35 AM, Roopa Prabhu wrote: > On Wed, Aug 28, 2019 at 10:26 PM Michal Kubecek <mkube...@suse.cz> wrote: >> >> On Wed, Aug 28, 2019 at 09:36:41PM -0700, Roopa Prabhu wrote: >>> >>> yes, correct. I mentioned that because I was wondering if we can >>> think along the same lines for this API. >>> eg >>> (a) RTM_NEWLINK always replaces the list attribute >>> (b) RTM_SETLINK with NLM_F_APPEND always appends to the list attribute >>> (c) RTM_DELLINK with NLM_F_APPEND updates the list attribute >>> >>> (It could be NLM_F_UPDATE if NLM_F_APPEND sounds weird in the del >>> case. I have not looked at the full dellink path if it will work >>> neatly..its been a busy day ) >> >> AFAICS rtnl_dellink() calls nlmsg_parse_deprecated() so that even >> current code would ignore any future attribute in RTM_DELLINK message >> (any kernel before the strict validation was introduced definitely will) >> and it does not seem to check NLM_F_APPEND or NLM_F_UPDATE either. So >> unless I missed something, such message would result in deleting the >> network device (if possible) with any kernel not implementing the >> feature. > > ok, ack. yes today it does. I was hinting if that can be changed to > support list update with a flag like the RTM_DELLINK AF_BRIDGE does > for vlan list del. > > so to summarize, i think we have discussed the following options to > update a netlink list attribute so far: > (a) encode an optional attribute/flag in the list attribute in > RTM_SETLINK to indicate if it is a add or del
The ALT_IFNAME attribute could also be a struct that has both the string and a flag. > (b) Use a flag in RTM_SETLINK and RTM_DELINK to indicate add/del > (close to bridge vlan add/del) > (c) introduce a separate generic msg type to add/del to a list > attribute (IIUC this does need a separate msg type per subsystem or > netlink API) >
