| Message ID | 1435871054-635096-2-git-send-email-tom@herbertland.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
On Thu, 2015-07-02 at 14:04 -0700, Tom Herbert wrote: > When setting up the first skb in a gro list we ensure that all the > headers up to skb_gro_offset have been pulled into head. In subsequent > uses of this skb (e.g. determining same_flow) it is assumed that the > headers can be accessed in the skb head. > > Signed-off-by: Tom Herbert <tom@herbertland.com> > --- > net/core/dev.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/net/core/dev.c b/net/core/dev.c > index 6778a99..05e0e37 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -4228,6 +4228,10 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff > } else { > napi->gro_count++; > } > + > + /* Ensure all headers are pulled into head for 1st skb */ > + skb_gro_header_slow(skb, skb_gro_offset(skb), 0); > + > NAPI_GRO_CB(skb)->count = 1; > NAPI_GRO_CB(skb)->age = jiffies; > NAPI_GRO_CB(skb)->last = skb; I do not see how we can reach this point without having headers already pulled. For example, tcp_gro_receive() has : off = skb_gro_offset(skb); hlen = off + sizeof(*th); th = skb_gro_header_fast(skb, off); if (skb_gro_header_hard(skb, hlen)) { th = skb_gro_header_slow(skb, hlen, off); if (unlikely(!th)) goto out; } So by definition, skb is put in gro_list only if it was fully validated as a GRO candidate. Given the complexity of your 2nd patch, I am stopping the review right now. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Jul 2, 2015 at 9:50 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote: > On Thu, 2015-07-02 at 14:04 -0700, Tom Herbert wrote: >> When setting up the first skb in a gro list we ensure that all the >> headers up to skb_gro_offset have been pulled into head. In subsequent >> uses of this skb (e.g. determining same_flow) it is assumed that the >> headers can be accessed in the skb head. >> >> Signed-off-by: Tom Herbert <tom@herbertland.com> >> --- >> net/core/dev.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/net/core/dev.c b/net/core/dev.c >> index 6778a99..05e0e37 100644 >> --- a/net/core/dev.c >> +++ b/net/core/dev.c >> @@ -4228,6 +4228,10 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff >> } else { >> napi->gro_count++; >> } >> + >> + /* Ensure all headers are pulled into head for 1st skb */ >> + skb_gro_header_slow(skb, skb_gro_offset(skb), 0); >> + >> NAPI_GRO_CB(skb)->count = 1; >> NAPI_GRO_CB(skb)->age = jiffies; >> NAPI_GRO_CB(skb)->last = skb; > > I do not see how we can reach this point without having headers already > pulled. > > For example, tcp_gro_receive() has : > > off = skb_gro_offset(skb); > hlen = off + sizeof(*th); > th = skb_gro_header_fast(skb, off); > if (skb_gro_header_hard(skb, hlen)) { > th = skb_gro_header_slow(skb, hlen, off); > if (unlikely(!th)) > goto out; > } > > So by definition, skb is put in gro_list only if it was fully validated as a GRO > candidate. > That code will access the data from fragments if possible, the skb_gro_header_slow is what pulls the data into head. In tcp_gro_receive we do tcp_hdr(p) on the 1st skbuf in a gro list so it is assumed there that the headers have been pulled into head. > Given the complexity of your 2nd patch, I am stopping the review right > now. > > > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, 2015-07-03 at 11:36 -0700, Tom Herbert wrote: > On Thu, Jul 2, 2015 at 9:50 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote: > > On Thu, 2015-07-02 at 14:04 -0700, Tom Herbert wrote: > >> When setting up the first skb in a gro list we ensure that all the > >> headers up to skb_gro_offset have been pulled into head. In subsequent > >> uses of this skb (e.g. determining same_flow) it is assumed that the > >> headers can be accessed in the skb head. > >> > >> Signed-off-by: Tom Herbert <tom@herbertland.com> > >> --- > >> net/core/dev.c | 4 ++++ > >> 1 file changed, 4 insertions(+) > >> > >> diff --git a/net/core/dev.c b/net/core/dev.c > >> index 6778a99..05e0e37 100644 > >> --- a/net/core/dev.c > >> +++ b/net/core/dev.c > >> @@ -4228,6 +4228,10 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff > >> } else { > >> napi->gro_count++; > >> } > >> + > >> + /* Ensure all headers are pulled into head for 1st skb */ > >> + skb_gro_header_slow(skb, skb_gro_offset(skb), 0); > >> + > >> NAPI_GRO_CB(skb)->count = 1; > >> NAPI_GRO_CB(skb)->age = jiffies; > >> NAPI_GRO_CB(skb)->last = skb; > > > > I do not see how we can reach this point without having headers already > > pulled. > > > > For example, tcp_gro_receive() has : > > > > off = skb_gro_offset(skb); > > hlen = off + sizeof(*th); > > th = skb_gro_header_fast(skb, off); > > if (skb_gro_header_hard(skb, hlen)) { > > th = skb_gro_header_slow(skb, hlen, off); > > if (unlikely(!th)) > > goto out; > > } > > > > So by definition, skb is put in gro_list only if it was fully validated as a GRO > > candidate. > > > That code will access the data from fragments if possible, the > skb_gro_header_slow is what pulls the data into head. In > tcp_gro_receive we do tcp_hdr(p) on the 1st skbuf in a gro list so it > is assumed there that the headers have been pulled into head. Not really, this code handles the current skb being passed to GRO engine. struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb) Then, we parse the gro list later : for (; (p = *head); head = &p->next) { And yes, all skb found in gro list already have all headers pulled. Your patch is not needed. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/core/dev.c b/net/core/dev.c index 6778a99..05e0e37 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4228,6 +4228,10 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff } else { napi->gro_count++; } + + /* Ensure all headers are pulled into head for 1st skb */ + skb_gro_header_slow(skb, skb_gro_offset(skb), 0); + NAPI_GRO_CB(skb)->count = 1; NAPI_GRO_CB(skb)->age = jiffies; NAPI_GRO_CB(skb)->last = skb;
When setting up the first skb in a gro list we ensure that all the headers up to skb_gro_offset have been pulled into head. In subsequent uses of this skb (e.g. determining same_flow) it is assumed that the headers can be accessed in the skb head. Signed-off-by: Tom Herbert <tom@herbertland.com> --- net/core/dev.c | 4 ++++ 1 file changed, 4 insertions(+)