Richard Gobert wrote:
{inet,ipv6}_gro_receive functions perform flush checks (ttl, flags, iph->id, ...) against all packets in a loop. These flush checks are relevant only to tcp flows, and as such they're used to determine whether the packets can be merged later in tcp_gro_receive.
These checks are not relevant to UDP packets.
These are network protocol coalescing invariants. Why would they be limited to certain transport protocols only?
Furthermore, they need to be done only once in tcp_gro_receive and only against the found p skb, since they only affect flush and not same_flow.
Levaraging the previous commit in the series, in which correct network header offsets are saved for both outer and inner network headers - allowing these checks to be done only once, in tcp_gro_receive. As a result, NAPI_GRO_CB(p)->flush is not used at all. In addition - flush_id checks are more declerative and contained in inet_gro_flush, thus removing
declarative
the need for flush_id in napi_gro_cb.
Signed-off-by: Richard Gobert richardbgobert@gmail.com
+static int inet_gro_flush(const struct iphdr *iph, const struct iphdr *iph2,
struct sk_buff *p, u32 outer)+{
- const u32 id = ntohl(*(__be32 *)&iph->id);
- const u32 id2 = ntohl(*(__be32 *)&iph2->id);
- const int flush_id = ntohs(id >> 16) - ntohs(id2 >> 16);
- const u16 count = NAPI_GRO_CB(p)->count;
- const u32 df = id & IP_DF;
- u32 is_atomic;
- int flush;
- /* All fields must match except length and checksum. */
- flush = (iph->ttl ^ iph2->ttl) | (iph->tos ^ iph2->tos) | (df ^ (id2 & IP_DF));
- /* When we receive our second frame we can make a decision on if we
* continue this flow as an atomic flow with a fixed ID or if we use* an incremdfenting ID.*/
Comment became garbled on move: incrementing
- if (count == 1) {
is_atomic = df && flush_id == 0;NAPI_GRO_CB(p)->is_atomic = is_atomic;- } else {
is_atomic = df && NAPI_GRO_CB(p)->is_atomic;- }
- /* Ignore outer IP ID value if based on atomic datagram. */
- outer = (outer && df) - 1;
- is_atomic--;
- return flush | ((flush_id ^ (count & is_atomic)) & outer);
+}