mac80211: optimize tx status processing

When a cooked monitor interface is active, ieee80211_tx_status()
generates a radiotap header for every single frame, even if it wasn't
injected and thus won't be sent to a monitor interface.
This patch reduces cpu utilization by moving the cooked monitor check a
bit earlier, before it generates the rtap header.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/net/mac80211/status.c b/net/mac80211/status.c
index 56d5b9a..11805a3 100644 (file)
--- a/net/mac80211/status.c
+++ b/net/mac80211/status.c
@@ -171,7 +171,7 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
        struct net_device *prev_dev = NULL;
        struct sta_info *sta, *tmp;
        int retry_count = -1, i;
-       bool injected;
+       bool send_to_cooked;
 
        for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
                /* the HW cannot have attempted that rate */
@@ -296,11 +296,15 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
        /* this was a transmitted frame, but now we want to reuse it */
        skb_orphan(skb);
 
+       /* Need to make a copy before skb->cb gets cleared */
+       send_to_cooked = !!(info->flags & IEEE80211_TX_CTL_INJECTED) ||
+                       (type != IEEE80211_FTYPE_DATA);
+
        /*
         * This is a bit racy but we can avoid a lot of work
         * with this test...
         */
-       if (!local->monitors && !local->cooked_mntrs) {
+       if (!local->monitors && (!send_to_cooked || !local->cooked_mntrs)) {
                dev_kfree_skb(skb);
                return;
        }
@@ -345,9 +349,6 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
        /* for now report the total retry_count */
        rthdr->data_retries = retry_count;
 
-       /* Need to make a copy before skb->cb gets cleared */
-       injected = !!(info->flags & IEEE80211_TX_CTL_INJECTED);
-
        /* XXX: is this sufficient for BPF? */
        skb_set_mac_header(skb, 0);
        skb->ip_summed = CHECKSUM_UNNECESSARY;
@@ -362,8 +363,7 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
                                continue;
 
                        if ((sdata->u.mntr_flags & MONITOR_FLAG_COOK_FRAMES) &&
-                           !injected &&
-                           (type == IEEE80211_FTYPE_DATA))
+                           !send_to_cooked)
                                continue;
 
                        if (prev_dev) {