On Mon, Oct 14, 2019 at 04:36:34PM +0800, Xin Long wrote: > On Thu, Oct 10, 2019 at 12:18 AM Neil Horman <nhorman@xxxxxxxxxxxxx> wrote: > > > > On Tue, Oct 08, 2019 at 11:28:32PM +0800, Xin Long wrote: > > > On Tue, Oct 8, 2019 at 9:02 PM David Laight <David.Laight@xxxxxxxxxx> wrote: > > > > > > > > From: Xin Long > > > > > Sent: 08 October 2019 12:25 > > > > > > > > > > This is a sockopt defined in section 7.3 of rfc7829: "Exposing > > > > > the Potentially Failed Path State", by which users can change > > > > > pf_expose per sock and asoc. > > > > > > > > If I read these patches correctly the default for this sockopt in 'enabled'. > > > > Doesn't this mean that old application binaries will receive notifications > > > > that they aren't expecting? > > > > > > > > I'd have thought that applications would be required to enable it. > > > If we do that, sctp_getsockopt_peer_addr_info() in patch 2/5 breaks. > > > > > I don't think we can safely do either of these things. Older > > applications still need to behave as they did prior to the introduction > > of this notification, and we shouldn't allow unexpected notifications to > > be sent. > Hi, Neil > > I think about again, and also talked with QE, we think to get unexpected > notifications shouldn't be a problem for user's applications. > On principle, I disagree. Regardless of what the RFC does, we shouldn't send notifications that an application aren't subscribed to. Just because QE doesn't think it should be a problem (and for their uses it may well not be an issue), we can't make that general assumption. > RFC actually keeps adding new notifications, and a user shouldn't expect > the specific notifications coming in some exact orders. They should just > ignore it and wait until the ones they expect. I don't think some users > would abort its application when getting an unexpected notification. > To make that assertion is to discount the purpose of the SCTP_EVENTS sockopt entirely. the SCTP_EVENTS option is a whitelist operation, so they expect to get what they subscribe to, and no more. > We should NACK patchset v3 and go with v2. What do you think? > No, we need to go with an option that maintains backwards compatibility without relying on the assumption that applications will just ignore events they didn't subscribe to. Davids example is a case in point. Neil > > > > What if you added a check in get_peer_addr_info to only return -EACCESS > > if pf_expose is 0 and the application isn't subscribed to the PF event? > > > > Neil > > > > > > > > > > David > > > > > > > > - > > > > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK > > > > Registration No: 1397386 (Wales) > > > > > > > >
