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Message-ID: <CALnjE+rJEtyL-QDrp0x+N_pCxDuR6soHkaY-OrswWrdZwfE2sQ@mail.gmail.com>
Date: Wed, 19 Nov 2014 00:06:19 -0800
From: Pravin Shelar <pshelar@...ira.com>
To: Jiri Pirko <jiri@...nulli.us>
Cc: netdev <netdev@...r.kernel.org>,
David Miller <davem@...emloft.net>,
Jamal Hadi Salim <jhs@...atatu.com>,
Tom Herbert <therbert@...gle.com>,
Eric Dumazet <edumazet@...gle.com>,
Willem de Bruijn <willemb@...gle.com>,
Daniel Borkmann <dborkman@...hat.com>, mst@...hat.com,
fw@...len.de, Paul.Durrant@...rix.com, Thomas Graf <tgraf@...g.ch>,
Cong Wang <cwang@...pensource.com>
Subject: Re: [patch net-next v3 8/9] net: move vlan pop/push functions into
common code
On Tue, Nov 18, 2014 at 1:37 PM, Jiri Pirko <jiri@...nulli.us> wrote:
> So it can be used from out of openvswitch code.
> Did couple of cosmetic changes on the way, namely variable naming and
> adding support for 8021AD proto.
>
> Signed-off-by: Jiri Pirko <jiri@...nulli.us>
> ---
>
> v2->v3
> - used previously introduced __vlan_insert_tag helper
> - used skb_push/pull to get skb->data into needed point
> - fixed skb->mac_len computation in skb_vlan_push pointed out by Pravin
> v1->v2:
> - adjusted to fix recent ovs changes
> - included change to use make_writable suggested by Eric
>
> include/linux/skbuff.h | 2 +
> net/core/skbuff.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++
> net/openvswitch/actions.c | 88 ++++++-------------------------------------
> 3 files changed, 109 insertions(+), 76 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index e045516..78c299f 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -2679,6 +2679,8 @@ unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
> struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
> struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
> int skb_ensure_writable(struct sk_buff *skb, int write_len);
> +int skb_vlan_pop(struct sk_buff *skb);
> +int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci);
>
> struct skb_checksum_ops {
> __wsum (*update)(const void *mem, int len, __wsum wsum);
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index d11bbe0..2f72e62 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -4163,6 +4163,101 @@ int skb_ensure_writable(struct sk_buff *skb, int write_len)
> }
> EXPORT_SYMBOL(skb_ensure_writable);
>
> +/* remove VLAN header from packet and update csum accordingly. */
> +static int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci)
> +{
> + struct vlan_hdr *vhdr;
> + unsigned int offset = skb->data - skb_mac_header(skb);
> + int err;
> +
> + __skb_push(skb, offset);
> + err = skb_ensure_writable(skb, VLAN_ETH_HLEN);
> + if (unlikely(err))
> + goto pull;
> +
> + skb_postpull_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
> +
> + vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
> + *vlan_tci = ntohs(vhdr->h_vlan_TCI);
> +
> + memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
> + __skb_pull(skb, VLAN_HLEN);
> +
> + vlan_set_encap_proto(skb, vhdr);
> + skb->mac_header += VLAN_HLEN;
> +
> + if (skb_network_offset(skb) < ETH_HLEN)
> + skb_set_network_header(skb, ETH_HLEN);
> +
> + skb_reset_mac_len(skb);
skb_reset_mac_len() sets length according to ethernet and network
offsets, but mpls expects mac-length to be offset to mpls header (ref.
skb_mpls_header()). Therefore rather than reset we need to subtract
VLAN_HLEN from mac_len. Same goes for vlan-push(), we can add
VLAN_HLEN.
> +pull:
> + __skb_pull(skb, offset);
> +
> + return err;
> +}
> +
> +int skb_vlan_pop(struct sk_buff *skb)
> +{
> + u16 vlan_tci;
> + __be16 vlan_proto;
> + int err;
> +
> + if (likely(vlan_tx_tag_present(skb))) {
> + skb->vlan_tci = 0;
> + } else {
> + if (unlikely((skb->protocol != htons(ETH_P_8021Q) &&
> + skb->protocol != htons(ETH_P_8021AD)) ||
> + skb->len < VLAN_ETH_HLEN))
> + return 0;
> +
> + err = __skb_vlan_pop(skb, &vlan_tci);
> + if (err)
> + return err;
> + }
> + /* move next vlan tag to hw accel tag */
> + if (likely((skb->protocol != htons(ETH_P_8021Q) &&
> + skb->protocol != htons(ETH_P_8021AD)) ||
> + skb->len < VLAN_ETH_HLEN))
> + return 0;
> +
> + vlan_proto = skb->protocol;
> + err = __skb_vlan_pop(skb, &vlan_tci);
> + if (unlikely(err))
> + return err;
> +
> + __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
> + return 0;
> +}
> +EXPORT_SYMBOL(skb_vlan_pop);
> +
> +int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
> +{
> + if (vlan_tx_tag_present(skb)) {
> + unsigned int offset = skb->data - skb_mac_header(skb);
> + int err;
> +
> + /* __vlan_insert_tag expect skb->data pointing to mac header.
> + * So change skb->data before calling it and change back to
> + * original position later
> + */
> + __skb_push(skb, offset);
> + err = __vlan_insert_tag(skb, skb->vlan_proto,
> + vlan_tx_tag_get(skb));
> + if (err)
> + return err;
> + skb->protocol = skb->vlan_proto;
> + skb_reset_mac_len(skb);
> + __skb_pull(skb, offset);
> +
> + if (skb->ip_summed == CHECKSUM_COMPLETE)
> + skb->csum = csum_add(skb->csum, csum_partial(skb->data
> + + (2 * ETH_ALEN), VLAN_HLEN, 0));
> + }
> + __vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
> + return 0;
> +}
> +EXPORT_SYMBOL(skb_vlan_push);
> +
> /**
> * alloc_skb_with_frags - allocate skb with page frags
> *
> diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
> index 7ffa377..ae7e1b2 100644
> --- a/net/openvswitch/actions.c
> +++ b/net/openvswitch/actions.c
> @@ -206,93 +206,27 @@ static int set_mpls(struct sk_buff *skb, struct sw_flow_key *key,
> return 0;
> }
>
> -/* remove VLAN header from packet and update csum accordingly. */
> -static int __pop_vlan_tci(struct sk_buff *skb, __be16 *current_tci)
> -{
> - struct vlan_hdr *vhdr;
> - int err;
> -
> - err = skb_ensure_writable(skb, VLAN_ETH_HLEN);
> - if (unlikely(err))
> - return err;
> -
> - skb_postpull_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
> -
> - vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
> - *current_tci = vhdr->h_vlan_TCI;
> -
> - memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
> - __skb_pull(skb, VLAN_HLEN);
> -
> - vlan_set_encap_proto(skb, vhdr);
> - skb->mac_header += VLAN_HLEN;
> -
> - if (skb_network_offset(skb) < ETH_HLEN)
> - skb_set_network_header(skb, ETH_HLEN);
> -
> - /* Update mac_len for subsequent MPLS actions */
> - skb_reset_mac_len(skb);
> - return 0;
> -}
> -
> static int pop_vlan(struct sk_buff *skb, struct sw_flow_key *key)
> {
> - __be16 tci;
> int err;
>
> - if (likely(vlan_tx_tag_present(skb))) {
> - skb->vlan_tci = 0;
> - } else {
> - if (unlikely(skb->protocol != htons(ETH_P_8021Q) ||
> - skb->len < VLAN_ETH_HLEN))
> - return 0;
> -
> - err = __pop_vlan_tci(skb, &tci);
> - if (err)
> - return err;
> - }
> - /* move next vlan tag to hw accel tag */
> - if (likely(skb->protocol != htons(ETH_P_8021Q) ||
> - skb->len < VLAN_ETH_HLEN)) {
> + err = skb_vlan_pop(skb);
> + if (vlan_tx_tag_present(skb))
> + invalidate_flow_key(key);
> + else
> key->eth.tci = 0;
> - return 0;
> - }
> -
> - invalidate_flow_key(key);
> - err = __pop_vlan_tci(skb, &tci);
> - if (unlikely(err))
> - return err;
> -
> - __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), ntohs(tci));
> - return 0;
> + return err;
> }
>
> static int push_vlan(struct sk_buff *skb, struct sw_flow_key *key,
> const struct ovs_action_push_vlan *vlan)
> {
> - if (unlikely(vlan_tx_tag_present(skb))) {
> - u16 current_tag;
> -
> - /* push down current VLAN tag */
> - current_tag = vlan_tx_tag_get(skb);
> -
> - skb = vlan_insert_tag_set_proto(skb, skb->vlan_proto,
> - current_tag);
> - if (!skb)
> - return -ENOMEM;
> - /* Update mac_len for subsequent MPLS actions */
> - skb->mac_len += VLAN_HLEN;
> -
> - if (skb->ip_summed == CHECKSUM_COMPLETE)
> - skb->csum = csum_add(skb->csum, csum_partial(skb->data
> - + (2 * ETH_ALEN), VLAN_HLEN, 0));
> -
> + if (vlan_tx_tag_present(skb))
> invalidate_flow_key(key);
> - } else {
> + else
> key->eth.tci = vlan->vlan_tci;
> - }
> - __vlan_hwaccel_put_tag(skb, vlan->vlan_tpid, ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);
> - return 0;
> + return skb_vlan_push(skb, vlan->vlan_tpid,
> + ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);
> }
>
> static int set_eth_addr(struct sk_buff *skb, struct sw_flow_key *key,
> @@ -858,8 +792,10 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
>
> case OVS_ACTION_ATTR_PUSH_VLAN:
> err = push_vlan(skb, key, nla_data(a));
> - if (unlikely(err)) /* skb already freed. */
> + if (unlikely(err)) {
> + dev_kfree_skb_any(skb);
> return err;
> + }
There is no need to check for error. Just break is sufficient. Error
checking is done after switch case.
> break;
>
> case OVS_ACTION_ATTR_POP_VLAN:
> --
> 1.9.3
>
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