+++ /dev/null
-From: Felix Fietkau <nbd@nbd.name>
-Date: Sun, 17 Mar 2019 18:11:30 +0100
-Subject: [PATCH] mac80211: optimize skb resizing
-
-When forwarding unicast packets from ethernet to batman-adv over 802.11s
-(with forwarding disabled), the typical required headroom to transmit
-encrypted packets on mt76 is 32 (802.11) + 6 (802.11s) + 8 (CCMP) +
-2 (padding) + 6 (LLC) + 18 (batman-adv) - 14 (old ethernet header) = 58 bytes.
-
-On systems where NET_SKB_PAD is 64 this leads to a call to pskb_expand_head
-for every packet, since mac80211 also tries to allocate 16 bytes status
-headroom for radiotap headers.
-
-This patch fixes these unnecessary reallocations by only requiring the extra
-status headroom in ieee80211_tx_monitor()
-If however a reallocation happens before that call, the status headroom gets
-added there as well, in order to avoid double reallocation.
-
-The patch also cleans up the code by moving the headroom calculation to
-ieee80211_skb_resize.
-
-Signed-off-by: Felix Fietkau <nbd@nbd.name>
----
-
---- a/net/mac80211/ieee80211_i.h
-+++ b/net/mac80211/ieee80211_i.h
-@@ -1762,6 +1762,9 @@ void ieee80211_clear_fast_xmit(struct st
- int ieee80211_tx_control_port(struct wiphy *wiphy, struct net_device *dev,
- const u8 *buf, size_t len,
- const u8 *dest, __be16 proto, bool unencrypted);
-+int ieee80211_skb_resize(struct ieee80211_local *local,
-+ struct ieee80211_sub_if_data *sdata,
-+ struct sk_buff *skb, int hdrlen, int hdr_add);
-
- /* HT */
- void ieee80211_apply_htcap_overrides(struct ieee80211_sub_if_data *sdata,
---- a/net/mac80211/status.c
-+++ b/net/mac80211/status.c
-@@ -671,6 +671,11 @@ void ieee80211_tx_monitor(struct ieee802
- }
- }
-
-+ if (ieee80211_skb_resize(local, NULL, skb, 0, 0)) {
-+ dev_kfree_skb(skb);
-+ return;
-+ }
-+
- /* send frame to monitor interfaces now */
- rtap_len = ieee80211_tx_radiotap_len(info);
- if (WARN_ON_ONCE(skb_headroom(skb) < rtap_len)) {
---- a/net/mac80211/tx.c
-+++ b/net/mac80211/tx.c
-@@ -1914,42 +1914,53 @@ static bool ieee80211_tx(struct ieee8021
- }
-
- /* device xmit handlers */
--
--enum ieee80211_encrypt {
-- ENCRYPT_NO,
-- ENCRYPT_MGMT,
-- ENCRYPT_DATA,
--};
--
--static int ieee80211_skb_resize(struct ieee80211_sub_if_data *sdata,
-- struct sk_buff *skb,
-- int head_need,
-- enum ieee80211_encrypt encrypt)
-+int ieee80211_skb_resize(struct ieee80211_local *local,
-+ struct ieee80211_sub_if_data *sdata,
-+ struct sk_buff *skb, int hdr_len, int hdr_extra)
- {
-- struct ieee80211_local *local = sdata->local;
-- bool enc_tailroom;
-- int tail_need = 0;
--
-- enc_tailroom = encrypt == ENCRYPT_MGMT ||
-- (encrypt == ENCRYPT_DATA &&
-- sdata->crypto_tx_tailroom_needed_cnt);
--
-- if (enc_tailroom) {
-- tail_need = IEEE80211_ENCRYPT_TAILROOM;
-- tail_need -= skb_tailroom(skb);
-- tail_need = max_t(int, tail_need, 0);
-+ struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
-+ struct ieee80211_hdr *hdr;
-+ int head_need, head_max;
-+ int tail_need, tail_max;
-+ bool enc_tailroom = false;
-+
-+ if (sdata && !hdr_len &&
-+ !(info->flags & IEEE80211_TX_INTFL_DONT_ENCRYPT)) {
-+ hdr = (struct ieee80211_hdr *) skb->data;
-+ enc_tailroom = (sdata->crypto_tx_tailroom_needed_cnt ||
-+ ieee80211_is_mgmt(hdr->frame_control));
-+ hdr_len += sdata->encrypt_headroom;
-+ }
-+
-+ head_need = head_max = hdr_len;
-+ tail_need = tail_max = 0;
-+ if (!sdata) {
-+ head_need = head_max = local->tx_headroom;
-+ } else {
-+ head_max += hdr_extra;
-+ head_max += max_t(int, local->tx_headroom,
-+ local->hw.extra_tx_headroom);
-+ head_need += local->hw.extra_tx_headroom;
-+
-+ tail_max = IEEE80211_ENCRYPT_TAILROOM;
-+ if (enc_tailroom)
-+ tail_need = tail_max;
- }
-
- if (skb_cloned(skb) &&
- (!ieee80211_hw_check(&local->hw, SUPPORTS_CLONED_SKBS) ||
- !skb_clone_writable(skb, ETH_HLEN) || enc_tailroom))
- I802_DEBUG_INC(local->tx_expand_skb_head_cloned);
-- else if (head_need || tail_need)
-+ else if (head_need > skb_headroom(skb) ||
-+ tail_need > skb_tailroom(skb))
- I802_DEBUG_INC(local->tx_expand_skb_head);
- else
- return 0;
-
-- if (pskb_expand_head(skb, head_need, tail_need, GFP_ATOMIC)) {
-+ head_max = max_t(int, 0, head_max - skb_headroom(skb));
-+ tail_max = max_t(int, 0, tail_max - skb_tailroom(skb));
-+
-+ if (pskb_expand_head(skb, head_max, tail_max, GFP_ATOMIC)) {
- wiphy_debug(local->hw.wiphy,
- "failed to reallocate TX buffer\n");
- return -ENOMEM;
-@@ -1964,24 +1975,9 @@ void ieee80211_xmit(struct ieee80211_sub
- {
- struct ieee80211_local *local = sdata->local;
- struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
-- struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
-- int headroom;
-- enum ieee80211_encrypt encrypt;
--
-- if (info->flags & IEEE80211_TX_INTFL_DONT_ENCRYPT)
-- encrypt = ENCRYPT_NO;
-- else if (ieee80211_is_mgmt(hdr->frame_control))
-- encrypt = ENCRYPT_MGMT;
-- else
-- encrypt = ENCRYPT_DATA;
--
-- headroom = local->tx_headroom;
-- if (encrypt != ENCRYPT_NO)
-- headroom += sdata->encrypt_headroom;
-- headroom -= skb_headroom(skb);
-- headroom = max_t(int, 0, headroom);
-+ struct ieee80211_hdr *hdr;
-
-- if (ieee80211_skb_resize(sdata, skb, headroom, encrypt)) {
-+ if (ieee80211_skb_resize(local, sdata, skb, 0, 0)) {
- ieee80211_free_txskb(&local->hw, skb);
- return;
- }
-@@ -2752,30 +2748,14 @@ static struct sk_buff *ieee80211_build_h
-
- skb_pull(skb, skip_header_bytes);
- padsize = ieee80211_hdr_padsize(&local->hw, hdrlen);
-- head_need = hdrlen + encaps_len + meshhdrlen - skb_headroom(skb);
-+ head_need = hdrlen + encaps_len + meshhdrlen;
- head_need += padsize;
-
-- /*
-- * So we need to modify the skb header and hence need a copy of
-- * that. The head_need variable above doesn't, so far, include
-- * the needed header space that we don't need right away. If we
-- * can, then we don't reallocate right now but only after the
-- * frame arrives at the master device (if it does...)
-- *
-- * If we cannot, however, then we will reallocate to include all
-- * the ever needed space. Also, if we need to reallocate it anyway,
-- * make it big enough for everything we may ever need.
-- */
--
-- if (head_need > 0 || skb_cloned(skb)) {
-- head_need += sdata->encrypt_headroom;
-- head_need += local->tx_headroom;
-- head_need = max_t(int, 0, head_need);
-- if (ieee80211_skb_resize(sdata, skb, head_need, ENCRYPT_DATA)) {
-- ieee80211_free_txskb(&local->hw, skb);
-- skb = NULL;
-- return ERR_PTR(-ENOMEM);
-- }
-+ if (ieee80211_skb_resize(local, sdata, skb, head_need,
-+ sdata->encrypt_headroom)) {
-+ ieee80211_free_txskb(&local->hw, skb);
-+ skb = NULL;
-+ return ERR_PTR(-ENOMEM);
- }
-
- if (encaps_data)
-@@ -3388,7 +3368,6 @@ static bool ieee80211_xmit_fast(struct i
- struct ieee80211_local *local = sdata->local;
- u16 ethertype = (skb->data[12] << 8) | skb->data[13];
- int extra_head = fast_tx->hdr_len - (ETH_HLEN - 2);
-- int hw_headroom = sdata->local->hw.extra_tx_headroom;
- struct ethhdr eth;
- struct ieee80211_tx_info *info;
- struct ieee80211_hdr *hdr = (void *)fast_tx->hdr;
-@@ -3440,10 +3419,7 @@ static bool ieee80211_xmit_fast(struct i
- * as the may-encrypt argument for the resize to not account for
- * more room than we already have in 'extra_head'
- */
-- if (unlikely(ieee80211_skb_resize(sdata, skb,
-- max_t(int, extra_head + hw_headroom -
-- skb_headroom(skb), 0),
-- ENCRYPT_NO))) {
-+ if (unlikely(ieee80211_skb_resize(local, sdata, skb, extra_head, 0))) {
- kfree_skb(skb);
- return true;
- }
projects / openwrt / openwrt.git / commitdiff