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Date: Fri, 7 Jun 2024 01:40:38 -0400
From: Christian Hopps <chopps@...pps.org>
To: devel@...ux-ipsec.org
Cc: Steffen Klassert <steffen.klassert@...unet.com>,
netdev@...r.kernel.org,
Christian Hopps <chopps@...pps.org>,
Christian Hopps <chopps@...n.net>
Subject: [PATCH ipsec-next v3 14/17] xfrm: iptfs: add reusing received skb for the tunnel egress packet
From: Christian Hopps <chopps@...n.net>
Add an optimization of re-using the tunnel outer skb re-transmission
of the inner packet to avoid skb allocation and copy.
Signed-off-by: Christian Hopps <chopps@...n.net>
---
net/xfrm/xfrm_iptfs.c | 126 +++++++++++++++++++++++++++++++++++-------
1 file changed, 105 insertions(+), 21 deletions(-)
diff --git a/net/xfrm/xfrm_iptfs.c b/net/xfrm/xfrm_iptfs.c
index a8d6ce2882b3..1abcbd7672d7 100644
--- a/net/xfrm/xfrm_iptfs.c
+++ b/net/xfrm/xfrm_iptfs.c
@@ -579,19 +579,20 @@ static int iptfs_input(struct xfrm_state *x, struct sk_buff *skb)
struct ip_iptfs_cc_hdr iptcch;
struct skb_seq_state skbseq;
struct list_head sublist; /* rename this it's just a list */
- struct sk_buff *first_skb, *next;
+ struct sk_buff *first_skb, *defer, *next;
const unsigned char *old_mac;
struct xfrm_iptfs_data *xtfs;
struct ip_iptfs_hdr *ipth;
struct iphdr *iph;
struct net *net;
- u32 remaining, iplen, iphlen, data, tail;
+ u32 remaining, first_iplen, iplen, iphlen, data, tail;
u32 blkoff, capturelen;
u64 seq;
xtfs = x->mode_data;
net = dev_net(skb->dev);
first_skb = NULL;
+ defer = NULL;
seq = __esp_seq(skb);
@@ -719,25 +720,94 @@ static int iptfs_input(struct xfrm_state *x, struct sk_buff *skb)
skb_prepare_seq_read(save, data, tail, &skbseq);
}
- if (!first_skb)
+ if (first_skb) {
+ skb = NULL;
+ } else {
first_skb = skb;
+ first_iplen = iplen;
+
+ /* We are going to skip over `data` bytes to reach the
+ * start of the IP header of `iphlen` len for `iplen`
+ * inner packet.
+ */
+
+ if (skb_has_frag_list(skb)) {
+ defer = skb;
+ skb = NULL;
+ } else if (data + iphlen <= skb_headlen(skb) &&
+ /* make sure our header is 32-bit aligned? */
+ /* ((uintptr_t)(skb->data + data) & 0x3) == 0 && */
+ skb_tailroom(skb) + tail - data >= iplen) {
+ /* Reuse the received skb.
+ *
+ * We have enough headlen to pull past any
+ * initial fragment data, leaving at least the
+ * IP header in the linear buffer space.
+ *
+ * For linear buffer space we only require that
+ * linear buffer space is large enough to
+ * eventually hold the entire reassembled
+ * packet (by including tailroom in the check).
+ *
+ * For non-linear tailroom is 0 and so we only
+ * re-use if the entire packet is present
+ * already.
+ *
+ * NOTE: there are many more options for
+ * sharing, KISS for now. Also, this can produce
+ * skb's with the IP header unaligned to 32
+ * bits. If that ends up being a problem then a
+ * check should be added to the conditional
+ * above that the header lies on a 32-bit
+ * boundary as well.
+ */
+ skb_pull(skb, data);
+
+ /* our range just changed */
+ data = 0;
+ tail = skb->len;
+ remaining = skb->len;
+
+ skb->protocol = protocol;
+ skb_mac_header_rebuild(skb);
+ if (skb->mac_len)
+ eth_hdr(skb)->h_proto = skb->protocol;
+
+ /* all pointers could be changed now reset walk */
+ skb_abort_seq_read(&skbseq);
+ skb_prepare_seq_read(skb, data, tail, &skbseq);
+ } else {
+ /* We couldn't reuse the input skb so allocate a
+ * new one.
+ */
+ defer = skb;
+ skb = NULL;
+ }
+
+ /* Don't trim `first_skb` until the end as we are
+ * walking that data now.
+ */
+ }
capturelen = min(iplen, remaining);
- skb = iptfs_pskb_extract_seq(iplen, &skbseq, data, capturelen);
if (!skb) {
- /* skip to next packet or done */
- data += capturelen;
- continue;
- }
- BUG_ON(skb->len != capturelen);
-
- skb->protocol = protocol;
- if (old_mac) {
- /* rebuild the mac header */
- skb_set_mac_header(skb, -first_skb->mac_len);
- memcpy(skb_mac_header(skb), old_mac,
- first_skb->mac_len);
- eth_hdr(skb)->h_proto = skb->protocol;
+ skb = iptfs_pskb_extract_seq(iplen, &skbseq, data,
+ capturelen);
+ if (!skb) {
+ /* skip to next packet or done */
+ data += capturelen;
+ continue;
+ }
+ BUG_ON(skb->len != capturelen);
+
+ skb->protocol = protocol;
+ if (old_mac) {
+ /* rebuild the mac header */
+ skb_set_mac_header(skb, -first_skb->mac_len);
+ memcpy(skb_mac_header(skb), old_mac,
+ first_skb->mac_len);
+ eth_hdr(skb)->h_proto = skb->protocol;
+ }
}
data += capturelen;
@@ -772,8 +842,19 @@ static int iptfs_input(struct xfrm_state *x, struct sk_buff *skb)
/* this should not happen from the above code */
XFRM_INC_STATS(dev_net(skb->dev), LINUX_MIB_XFRMINIPTFSERROR);
+ if (first_skb && first_iplen && !defer && first_skb != xtfs->ra_newskb) {
+ /* first_skb is queued b/c !defer and not partial */
+ if (pskb_trim(first_skb, first_iplen)) {
+ /* error trimming */
+ list_del(&first_skb->list);
+ defer = first_skb;
+ }
+ first_skb->ip_summed = CHECKSUM_NONE;
+ }
+
/* Send the packets! */
list_for_each_entry_safe(skb, next, &sublist, list) {
+ BUG_ON(skb == defer);
skb_list_del_init(skb);
if (xfrm_input(skb, 0, 0, -3))
kfree_skb(skb);
@@ -783,12 +864,15 @@ static int iptfs_input(struct xfrm_state *x, struct sk_buff *skb)
skb = skbseq.root_skb;
skb_abort_seq_read(&skbseq);
- if (first_skb) {
- consume_skb(first_skb);
- } else {
+ if (defer) {
+ consume_skb(defer);
+ } else if (!first_skb) {
/* skb is the original passed in skb, but we didn't get far
- * enough to process it as the first_skb.
+ * enough to process it as the first_skb, if we had it would
+ * either be save in ra_newskb, trimmed and sent on as an skb or
+ * placed in defer to be freed.
*/
+ BUG_ON(!skb);
kfree_skb(skb);
}
--
2.45.2
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