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[34.150.146.164]) by smtp.gmail.com with ESMTPSA id j13-20020a0cf30d000000b0069b584cd2dbsm6593546qvl.5.2024.04.24.19.45.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Apr 2024 19:45:55 -0700 (PDT) Date: Wed, 24 Apr 2024 22:45:55 -0400 From: Willem de Bruijn To: Richard Gobert , davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, dsahern@kernel.org, willemdebruijn.kernel@gmail.com, alobakin@pm.me, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Richard Gobert Message-ID: <6629c3e399f65_1bd6b029423@willemb.c.googlers.com.notmuch> In-Reply-To: <20240424163045.123528-3-richardbgobert@gmail.com> References: <20240424163045.123528-1-richardbgobert@gmail.com> <20240424163045.123528-3-richardbgobert@gmail.com> Subject: Re: [PATCH net v3 2/2] net: gro: add flush check in udp_gro_receive_segment Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Richard Gobert wrote: > GRO-GSO path is supposed to be transparent and as such L3 flush checks are > relevant to all UDP flows merging in GRO. This patch uses the same logic > and code from tcp_gro_receive, terminating merge if flush is non zero. > > Fixes: 36707061d6ba ("udp: allow forwarding of plain (non-fraglisted) UDP GRO packets") Should this be Fixes: e20cf8d3f1f7 ("udp: implement GRO for plain UDP sockets.") > net/ipv4/udp_offload.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c > index fd29d21d579c..8721fe5beca2 100644 > --- a/net/ipv4/udp_offload.c > +++ b/net/ipv4/udp_offload.c > @@ -471,6 +471,7 @@ static struct sk_buff *udp_gro_receive_segment(struct list_head *head, > struct sk_buff *p; > unsigned int ulen; > int ret = 0; > + int flush; > > /* requires non zero csum, for symmetry with GSO */ > if (!uh->check) { > @@ -504,13 +505,22 @@ static struct sk_buff *udp_gro_receive_segment(struct list_head *head, > return p; > } > > + flush = NAPI_GRO_CB(p)->flush; > + > + if (NAPI_GRO_CB(p)->flush_id != 1 || > + NAPI_GRO_CB(p)->count != 1 || > + !NAPI_GRO_CB(p)->is_atomic) > + flush |= NAPI_GRO_CB(p)->flush_id; > + else > + NAPI_GRO_CB(p)->is_atomic = false; > + > /* Terminate the flow on len mismatch or if it grow "too much". > * Under small packet flood GRO count could elsewhere grow a lot > * leading to excessive truesize values. > * On len mismatch merge the first packet shorter than gso_size, > * otherwise complete the GRO packet. > */ > - if (ulen > ntohs(uh2->len)) { > + if (ulen > ntohs(uh2->len) || flush) { > pp = p; I suppose this branch already could immediately return p. And avoid a level of indentation below. But agreed to not change that in this bug fix.