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202 lines
6.9 KiB
Diff
202 lines
6.9 KiB
Diff
From: Felix Fietkau <nbd@nbd.name>
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Date: Sun, 17 Mar 2019 18:11:30 +0100
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Subject: [PATCH] mac80211: optimize skb resizing
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When forwarding unicast packets from ethernet to batman-adv over 802.11s
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(with forwarding disabled), the typical required headroom to transmit
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encrypted packets on mt76 is 32 (802.11) + 6 (802.11s) + 8 (CCMP) +
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2 (padding) + 6 (LLC) + 18 (batman-adv) - 14 (old ethernet header) = 58 bytes.
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On systems where NET_SKB_PAD is 64 this leads to a call to pskb_expand_head
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for every packet, since mac80211 also tries to allocate 16 bytes status
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headroom for radiotap headers.
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This patch fixes these unnecessary reallocations by only requiring the extra
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status headroom in ieee80211_tx_monitor()
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If however a reallocation happens before that call, the status headroom gets
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added there as well, in order to avoid double reallocation.
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The patch also cleans up the code by moving the headroom calculation to
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ieee80211_skb_resize.
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Signed-off-by: Felix Fietkau <nbd@nbd.name>
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---
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--- a/net/mac80211/ieee80211_i.h
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+++ b/net/mac80211/ieee80211_i.h
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@@ -1809,6 +1809,9 @@ int ieee80211_tx_control_port(struct wip
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u64 *cookie);
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int ieee80211_probe_mesh_link(struct wiphy *wiphy, struct net_device *dev,
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const u8 *buf, size_t len);
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+int ieee80211_skb_resize(struct ieee80211_local *local,
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+ struct ieee80211_sub_if_data *sdata,
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+ struct sk_buff *skb, int hdrlen, int hdr_add);
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/* HT */
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void ieee80211_apply_htcap_overrides(struct ieee80211_sub_if_data *sdata,
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--- a/net/mac80211/status.c
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+++ b/net/mac80211/status.c
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@@ -835,6 +835,11 @@ void ieee80211_tx_monitor(struct ieee802
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struct net_device *prev_dev = NULL;
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int rtap_len;
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+ if (ieee80211_skb_resize(local, NULL, skb, 0, 0)) {
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+ dev_kfree_skb(skb);
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+ return;
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+ }
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+
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/* send frame to monitor interfaces now */
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rtap_len = ieee80211_tx_radiotap_len(info, status);
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if (WARN_ON_ONCE(skb_headroom(skb) < rtap_len)) {
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--- a/net/mac80211/tx.c
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+++ b/net/mac80211/tx.c
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@@ -1937,37 +1937,53 @@ static bool ieee80211_tx(struct ieee8021
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}
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/* device xmit handlers */
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-
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-static int ieee80211_skb_resize(struct ieee80211_sub_if_data *sdata,
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- struct sk_buff *skb,
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- int head_need, bool may_encrypt)
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+int ieee80211_skb_resize(struct ieee80211_local *local,
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+ struct ieee80211_sub_if_data *sdata,
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+ struct sk_buff *skb, int hdr_len, int hdr_extra)
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{
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- struct ieee80211_local *local = sdata->local;
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+ struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
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struct ieee80211_hdr *hdr;
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- bool enc_tailroom;
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- int tail_need = 0;
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-
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- hdr = (struct ieee80211_hdr *) skb->data;
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- enc_tailroom = may_encrypt &&
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- (sdata->crypto_tx_tailroom_needed_cnt ||
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- ieee80211_is_mgmt(hdr->frame_control));
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-
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- if (enc_tailroom) {
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- tail_need = IEEE80211_ENCRYPT_TAILROOM;
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- tail_need -= skb_tailroom(skb);
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- tail_need = max_t(int, tail_need, 0);
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+ int head_need, head_max;
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+ int tail_need, tail_max;
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+ bool enc_tailroom = false;
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+
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+ if (sdata && !hdr_len &&
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+ !(info->flags & IEEE80211_TX_INTFL_DONT_ENCRYPT)) {
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+ hdr = (struct ieee80211_hdr *) skb->data;
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+ enc_tailroom = (sdata->crypto_tx_tailroom_needed_cnt ||
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+ ieee80211_is_mgmt(hdr->frame_control));
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+ hdr_len += sdata->encrypt_headroom;
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+ }
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+
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+ head_need = head_max = hdr_len;
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+ tail_need = tail_max = 0;
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+ if (!sdata) {
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+ head_need = head_max = local->tx_headroom;
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+ } else {
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+ head_max += hdr_extra;
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+ head_max += max_t(int, local->tx_headroom,
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+ local->hw.extra_tx_headroom);
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+ head_need += local->hw.extra_tx_headroom;
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+
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+ tail_max = IEEE80211_ENCRYPT_TAILROOM;
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+ if (enc_tailroom)
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+ tail_need = tail_max;
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}
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if (skb_cloned(skb) &&
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(!ieee80211_hw_check(&local->hw, SUPPORTS_CLONED_SKBS) ||
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!skb_clone_writable(skb, ETH_HLEN) || enc_tailroom))
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I802_DEBUG_INC(local->tx_expand_skb_head_cloned);
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- else if (head_need || tail_need)
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+ else if (head_need > skb_headroom(skb) ||
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+ tail_need > skb_tailroom(skb))
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I802_DEBUG_INC(local->tx_expand_skb_head);
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else
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return 0;
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- if (pskb_expand_head(skb, head_need, tail_need, GFP_ATOMIC)) {
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+ head_max = max_t(int, 0, head_max - skb_headroom(skb));
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+ tail_max = max_t(int, 0, tail_max - skb_tailroom(skb));
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+
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+ if (pskb_expand_head(skb, head_max, tail_max, GFP_ATOMIC)) {
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wiphy_debug(local->hw.wiphy,
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"failed to reallocate TX buffer\n");
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return -ENOMEM;
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@@ -1983,18 +1999,8 @@ void ieee80211_xmit(struct ieee80211_sub
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struct ieee80211_local *local = sdata->local;
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struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
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struct ieee80211_hdr *hdr;
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- int headroom;
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- bool may_encrypt;
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-
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- may_encrypt = !(info->flags & IEEE80211_TX_INTFL_DONT_ENCRYPT);
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- headroom = local->tx_headroom;
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- if (may_encrypt)
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- headroom += sdata->encrypt_headroom;
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- headroom -= skb_headroom(skb);
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- headroom = max_t(int, 0, headroom);
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-
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- if (ieee80211_skb_resize(sdata, skb, headroom, may_encrypt)) {
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+ if (ieee80211_skb_resize(local, sdata, skb, 0, 0)) {
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ieee80211_free_txskb(&local->hw, skb);
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return;
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}
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@@ -2809,29 +2815,13 @@ static struct sk_buff *ieee80211_build_h
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}
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skb_pull(skb, skip_header_bytes);
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- head_need = hdrlen + encaps_len + meshhdrlen - skb_headroom(skb);
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+ head_need = hdrlen + encaps_len + meshhdrlen;
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- /*
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- * So we need to modify the skb header and hence need a copy of
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- * that. The head_need variable above doesn't, so far, include
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- * the needed header space that we don't need right away. If we
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- * can, then we don't reallocate right now but only after the
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- * frame arrives at the master device (if it does...)
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- *
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- * If we cannot, however, then we will reallocate to include all
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- * the ever needed space. Also, if we need to reallocate it anyway,
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- * make it big enough for everything we may ever need.
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- */
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-
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- if (head_need > 0 || skb_cloned(skb)) {
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- head_need += sdata->encrypt_headroom;
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- head_need += local->tx_headroom;
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- head_need = max_t(int, 0, head_need);
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- if (ieee80211_skb_resize(sdata, skb, head_need, true)) {
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- ieee80211_free_txskb(&local->hw, skb);
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- skb = NULL;
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- return ERR_PTR(-ENOMEM);
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- }
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+ if (ieee80211_skb_resize(local, sdata, skb, head_need,
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+ sdata->encrypt_headroom)) {
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+ ieee80211_free_txskb(&local->hw, skb);
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+ skb = NULL;
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+ return ERR_PTR(-ENOMEM);
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}
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if (encaps_data)
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@@ -3446,7 +3436,6 @@ static bool ieee80211_xmit_fast(struct i
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struct ieee80211_local *local = sdata->local;
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u16 ethertype = (skb->data[12] << 8) | skb->data[13];
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int extra_head = fast_tx->hdr_len - (ETH_HLEN - 2);
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- int hw_headroom = sdata->local->hw.extra_tx_headroom;
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struct ethhdr eth;
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struct ieee80211_tx_info *info;
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struct ieee80211_hdr *hdr = (void *)fast_tx->hdr;
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@@ -3498,10 +3487,7 @@ static bool ieee80211_xmit_fast(struct i
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* as the may-encrypt argument for the resize to not account for
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* more room than we already have in 'extra_head'
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*/
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- if (unlikely(ieee80211_skb_resize(sdata, skb,
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- max_t(int, extra_head + hw_headroom -
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- skb_headroom(skb), 0),
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- false))) {
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+ if (unlikely(ieee80211_skb_resize(local, sdata, skb, extra_head, 0))) {
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kfree_skb(skb);
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return true;
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}
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