On 31/01/2022 01:24, Dmitry V. Levin wrote: > On Tue, Dec 28, 2021 at 09:06:10PM +0800, Tony Lu wrote: >> This adds net namespace ID to diag of linkgroup, helps us to distinguish >> different namespaces, and net_cookie is unique in the whole system. >> > > I'm sorry but this is an ABI regression. > > Since struct smc_diag_lgrinfo contains an object of type "struct smc_diag_linkinfo", > offset of all subsequent members of struct smc_diag_lgrinfo is changed by > this patch. > > As result, applications compiled with the old version of struct smc_diag_linkinfo > will receive garbage in struct smc_diag_lgrinfo.role if the kernel implements > this new version of struct smc_diag_linkinfo. > Good catch! This patch adds 2 ways to provide the net_cookie to user space, one is over the new netlink interface, and the other is using the old smc_diag way. Imho to use the new netlink interface is good enough, there is no need to touch the smc_diag ABI. We already started adding new fields to the netlink interface only, this flexibility is the reason why we added this interface initially. So a patch that removes __aligned_u64 net_cookie; and .lnk[0].net_cookie = net->net_cookie, should solve the issue. Thoughts?
