Hi all, Also, for those changes to have an effect, a new eBPF skeleton must be generated.
On Fri, Apr 28, 2023 at 1:58 PM Andrew Melnichenko <and...@daynix.com> wrote: > > Hi all, > I don't think that checking DF flag is a case for figuring out that > the packet is a fragment of some big datagram. > For nonfragmented packets, DF may not be set. > We need to check that the fragment offset is 0. > Actually, it's a good idea to check that MF flag is not set too. So we > can find the first fragment that doesn't require steering. > So the code may look something like this: > ``` > info->is_fragmented = !!(bpf_ntohs(ip.frag_off) & (0x2000 | 0x1fff)); > // checking MF and frag offset. > OR > info->is_fragmented = !!(bpf_ntohs(ip.frag_off) & ~0x4000); // if we > consider that CE always 0(which is always should be) > ``` > > On Sun, Apr 23, 2023 at 9:12 AM Yan Vugenfirer <yvuge...@redhat.com> wrote: > > > > FYI > > > > ---------- Forwarded message --------- > > From: luwenpeng <lwp_1...@163.com> > > Date: Fri, Apr 21, 2023 at 3:21 PM > > Subject: [PATCH] tools/ebpf: Fix IPv4 fragmentation identify > > To: <qemu-devel@nongnu.org> > > Cc: <jasow...@redhat.com>, luwenpeng <lwp_1...@163.com> > > > > > > The meaning of the bit flag in ip.frag_off is Don`t fragmented > > When judging IPv4 is_fragmented according to ip.frag_off, > > should use !(bpf_ntohs(ip.frag_off) & 0x4000) instead of !!ip.frag_off > > > > Signed-off-by: WenPeng Lu <lwp_1...@163.com> > > --- > > tools/ebpf/rss.bpf.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/tools/ebpf/rss.bpf.c b/tools/ebpf/rss.bpf.c > > index 20f227e2ac..e77b764f3d 100644 > > --- a/tools/ebpf/rss.bpf.c > > +++ b/tools/ebpf/rss.bpf.c > > @@ -317,7 +317,7 @@ static inline int parse_packet(struct __sk_buff *skb, > > > > info->in_src = ip.saddr; > > info->in_dst = ip.daddr; > > - info->is_fragmented = !!ip.frag_off; > > + info->is_fragmented = !(bpf_ntohs(ip.frag_off) & 0x4000); > > > > l4_protocol = ip.protocol; > > l4_offset = ip.ihl * 4; > > -- > > 2.30.1 (Apple Git-130) > > > >
