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Message-ID: <28f7885f-1084-d790-fff2-96d4c4bf54a6@iogearbox.net> Date: Sat, 2 Feb 2019 00:00:36 +0100 From: Daniel Borkmann <daniel@...earbox.net> To: Jakub Kicinski <jakub.kicinski@...ronome.com> Cc: Maciej Fijalkowski <maciejromanfijalkowski@...il.com>, ast@...nel.org, netdev@...r.kernel.org, brouer@...hat.com, john.fastabend@...il.com Subject: Re: [PATCH bpf-next v5 7/8] libbpf: Add a support for getting xdp prog id on ifindex On 02/01/2019 10:47 PM, Jakub Kicinski wrote: > On Fri, 1 Feb 2019 22:43:39 +0100, Daniel Borkmann wrote: >> On 02/01/2019 01:19 AM, Maciej Fijalkowski wrote: >>> Since we have a dedicated netlink attributes for xdp setup on a >>> particular interface, it is now possible to retrieve the program id that >>> is currently attached to the interface. The use case is targeted for >>> sample xdp programs, which will store the program id just after loading >>> bpf program onto iface. On shutdown, the sample will make sure that it >>> can unload the program by querying again the iface and verifying that >>> both program id's matches. >>> >>> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com> >>> Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com> >> [...] >>> +int bpf_get_link_xdp_id(int ifindex, __u32 *prog_id, __u32 flags) >>> +{ >>> + struct xdp_id_md xdp_id = {}; >>> + int sock, ret; >>> + __u32 nl_pid; >>> + __u32 mask; >>> + >>> + if (flags & ~XDP_FLAGS_MASK) >>> + return -EINVAL; >>> + >>> + /* Check whether the single {HW,DRV,SKB} mode is set */ >>> + flags &= (XDP_FLAGS_SKB_MODE | XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE); >>> + mask = flags - 1; >>> + if (flags && flags & mask) >>> + return -EINVAL; >>> + >>> + sock = libbpf_netlink_open(&nl_pid); >>> + if (sock < 0) >>> + return sock; >>> + >>> + xdp_id.ifindex = ifindex; >>> + xdp_id.flags = flags; >>> + >>> + ret = libbpf_nl_get_link(sock, nl_pid, get_xdp_id, &xdp_id); >>> + if (!ret) >>> + *prog_id = xdp_id.id; >>> + >>> + close(sock); >>> + return ret; >>> +} >> >> Btw, is anyone going to follow-up on XDP_ATTACHED_MULTI support as well >> later on? > > I haven't tested to be honest, but I think Maciek got that right - > get_xdp_id_attr() should return IFLA_XDP_PROG_ID or a mode-specific > attr based on flags. And there is a check that only flag is set. > > Or do you mean retrieving all program ids with one dump? Yeah was thinking about the latter, but agree it's fine and probably cleaner this way here.
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