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net: add vlan_get_protocol_offset_inline() helper

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skb_protocol() is bloated, and forces slow stack canaries in many
fast paths.

Add vlan_get_protocol_offset_inline() which deals with the non-vlan
common cases.

__vlan_get_protocol_offset() is now out of line.

It returns a vlan_type_depth struct to avoid stack canaries in callers.

struct vlan_type_depth {
       __be16 type;
       u16 depth;
};

$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/2 grow/shrink: 0/22 up/down: 0/-6320 (-6320)
Function                                     old     new   delta
vlan_get_protocol_dgram                       61      59      -2
__pfx_skb_protocol                            16       -     -16
__vlan_get_protocol_offset                   307     273     -34
tap_get_user                                1374    1207    -167
ip_md_tunnel_xmit                           1625    1452    -173
tap_sendmsg                                  940     753    -187
netif_skb_features                          1079     866    -213
netem_enqueue                               3017    2800    -217
vlan_parse_protocol                          271      50    -221
tso_start                                    567     344    -223
fq_dequeue                                  1908    1685    -223
skb_network_protocol                         434     205    -229
ip6_tnl_xmit                                2639    2409    -230
br_dev_queue_push_xmit                       474     236    -238
skb_protocol                                 258       -    -258
packet_parse_headers                         621     357    -264
__ip6_tnl_rcv                               1306    1039    -267
skb_csum_hwoffload_help                      515     224    -291
ip_tunnel_xmit                              2635    2339    -296
sch_frag_xmit_hook                          1582    1233    -349
bpf_skb_ecn_set_ce                           868     457    -411
IP6_ECN_decapsulate                         1297     768    -529
ip_tunnel_rcv                               2121    1489    -632
ipip6_rcv                                   2572    1922    -650
Total: Before=24892803, After=24886483, chg -0.03%

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260204053023.1622775-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Eric Dumazet
2026-02-04 05:30:23 +00:00
committed by Paolo Abeni
parent 770e112634
commit 7a4cd71fa4
3 changed files with 61 additions and 31 deletions
Download Patch File Download Diff File Expand all files Collapse all files

51
include/linux/if_vlan.h
View File

@@ -594,8 +594,17 @@ static inline int vlan_get_tag(const struct sk_buff *skb, u16 *vlan_tci)
}
}
struct vlan_type_depth {
__be16 type;
u16 depth;
};
struct vlan_type_depth __vlan_get_protocol_offset(const struct sk_buff *skb,
__be16 type,
int mac_offset);
/**
* __vlan_get_protocol_offset() - get protocol EtherType.
* vlan_get_protocol_offset_inline() - get protocol EtherType.
* @skb: skbuff to query
* @type: first vlan protocol
* @mac_offset: MAC offset
@@ -604,40 +613,24 @@ static inline int vlan_get_tag(const struct sk_buff *skb, u16 *vlan_tci)
* Returns: the EtherType of the packet, regardless of whether it is
* vlan encapsulated (normal or hardware accelerated) or not.
*/
static inline __be16 __vlan_get_protocol_offset(const struct sk_buff *skb,
__be16 type,
int mac_offset,
int *depth)
static inline
__be16 vlan_get_protocol_offset_inline(const struct sk_buff *skb,
__be16 type,
int mac_offset,
int *depth)
{
unsigned int vlan_depth = skb->mac_len, parse_depth = VLAN_MAX_DEPTH;
/* if type is 802.1Q/AD then the header should already be
* present at mac_len - VLAN_HLEN (if mac_len > 0), or at
* ETH_HLEN otherwise
*/
if (eth_type_vlan(type)) {
if (vlan_depth) {
if (WARN_ON(vlan_depth < VLAN_HLEN))
return 0;
vlan_depth -= VLAN_HLEN;
} else {
vlan_depth = ETH_HLEN;
}
do {
struct vlan_hdr vhdr, *vh;
struct vlan_type_depth res;
vh = skb_header_pointer(skb, mac_offset + vlan_depth,
sizeof(vhdr), &vhdr);
if (unlikely(!vh || !--parse_depth))
return 0;
res = __vlan_get_protocol_offset(skb, type, mac_offset);
type = vh->h_vlan_encapsulated_proto;
vlan_depth += VLAN_HLEN;
} while (eth_type_vlan(type));
if (depth && res.type)
*depth = res.depth;
return res.type;
}
if (depth)
*depth = vlan_depth;
*depth = skb->mac_len;
return type;
}
@@ -645,7 +638,7 @@ static inline __be16 __vlan_get_protocol_offset(const struct sk_buff *skb,
static inline __be16 __vlan_get_protocol(const struct sk_buff *skb, __be16 type,
int *depth)
{
return __vlan_get_protocol_offset(skb, type, 0, depth);
return vlan_get_protocol_offset_inline(skb, type, 0, depth);
}
/**

36
net/core/skbuff.c
View File

@@ -7444,3 +7444,39 @@ void __put_netmem(netmem_ref netmem)
net_devmem_put_net_iov(netmem_to_net_iov(netmem));
}
EXPORT_SYMBOL(__put_netmem);
struct vlan_type_depth __vlan_get_protocol_offset(const struct sk_buff *skb,
__be16 type,
int mac_offset)
{
unsigned int vlan_depth = skb->mac_len, parse_depth = VLAN_MAX_DEPTH;
/* if type is 802.1Q/AD then the header should already be
* present at mac_len - VLAN_HLEN (if mac_len > 0), or at
* ETH_HLEN otherwise
*/
if (vlan_depth) {
if (WARN_ON_ONCE(vlan_depth < VLAN_HLEN))
return (struct vlan_type_depth) { 0 };
vlan_depth -= VLAN_HLEN;
} else {
vlan_depth = ETH_HLEN;
}
do {
struct vlan_hdr vhdr, *vh;
vh = skb_header_pointer(skb, mac_offset + vlan_depth,
sizeof(vhdr), &vhdr);
if (unlikely(!vh || !--parse_depth))
return (struct vlan_type_depth) { 0 };
type = vh->h_vlan_encapsulated_proto;
vlan_depth += VLAN_HLEN;
} while (eth_type_vlan(type));
return (struct vlan_type_depth) {
.type = type,
.depth = vlan_depth
};
}
EXPORT_SYMBOL(__vlan_get_protocol_offset);

5
net/packet/af_packet.c
View File

@@ -572,8 +572,9 @@ static __be16 vlan_get_protocol_dgram(const struct sk_buff *skb)
__be16 proto = skb->protocol;
if (unlikely(eth_type_vlan(proto)))
proto = __vlan_get_protocol_offset(skb, proto,
skb_mac_offset(skb), NULL);
proto = vlan_get_protocol_offset_inline(skb, proto,
skb_mac_offset(skb),
NULL);
return proto;
}