mac80211: parse radiotap header earlier

We can now move the radiotap header parsing into
ieee80211_monitor_start_xmit(). This moves it out of
the hotpath, and also helps the code since now the
radiotap header will no longer be present in
ieee80211_xmit() etc. which is easier to understand.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 89 insertions, 116 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 05f102197cfe..021317367d55 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -349,8 +349,6 @@ struct ieee80211_bss_conf {
  * @IEEE80211_TX_INTFL_RETRANSMISSION: This frame is being retransmitted
  *      after TX status because the destination was asleep, it must not
  *      be modified again (no seqno assignment, crypto, etc.)
- * @IEEE80211_TX_INTFL_HAS_RADIOTAP: This frame was injected and still
- *      has a radiotap header at skb->data.
  * @IEEE80211_TX_INTFL_NL80211_FRAME_TX: Frame was requested through nl80211
  *      MLME command (internal to mac80211 to figure out whether to send TX
  *      status to user space)
@@ -402,7 +400,7 @@ enum mac80211_tx_control_flags {
         IEEE80211_TX_CTL_POLL_RESPONSE          = BIT(17),
         IEEE80211_TX_CTL_MORE_FRAMES            = BIT(18),
         IEEE80211_TX_INTFL_RETRANSMISSION       = BIT(19),
-        IEEE80211_TX_INTFL_HAS_RADIOTAP         = BIT(20),
+        /* hole at 20, use later */
         IEEE80211_TX_INTFL_NL80211_FRAME_TX     = BIT(21),
         IEEE80211_TX_CTL_LDPC                   = BIT(22),
         IEEE80211_TX_CTL_STBC                   = BIT(23) | BIT(24),
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 7f7d45cf77d1..3d2b6b2749f6 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1035,103 +1035,6 @@ ieee80211_tx_h_calculate_duration(struct ieee80211_tx_data *tx)
 
 /* actual transmit path */
 
-/*
- * deal with packet injection down monitor interface
- * with Radiotap Header -- only called for monitor mode interface
- */
-static bool __ieee80211_parse_tx_radiotap(struct ieee80211_tx_data *tx,
-                                          struct sk_buff *skb)
-{
-        /*
-         * this is the moment to interpret and discard the radiotap header that
-         * must be at the start of the packet injected in Monitor mode
-         *
-         * Need to take some care with endian-ness since radiotap
-         * args are little-endian
-         */
-
-        struct ieee80211_radiotap_iterator iterator;
-        struct ieee80211_radiotap_header *rthdr =
-                (struct ieee80211_radiotap_header *) skb->data;
-        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
-        int ret = ieee80211_radiotap_iterator_init(&iterator, rthdr, skb->len,
-                                                   NULL);
-        u16 txflags;
-
-        info->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT |
-                       IEEE80211_TX_CTL_DONTFRAG;
-
-        /*
-         * for every radiotap entry that is present
-         * (ieee80211_radiotap_iterator_next returns -ENOENT when no more
-         * entries present, or -EINVAL on error)
-         */
-
-        while (!ret) {
-                ret = ieee80211_radiotap_iterator_next(&iterator);
-
-                if (ret)
-                        continue;
-
-                /* see if this argument is something we can use */
-                switch (iterator.this_arg_index) {
-                /*
-                 * You must take care when dereferencing iterator.this_arg
-                 * for multibyte types... the pointer is not aligned.  Use
-                 * get_unaligned((type *)iterator.this_arg) to dereference
-                 * iterator.this_arg for type "type" safely on all arches.
-                */
-                case IEEE80211_RADIOTAP_FLAGS:
-                        if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FCS) {
-                                /*
-                                 * this indicates that the skb we have been
-                                 * handed has the 32-bit FCS CRC at the end...
-                                 * we should react to that by snipping it off
-                                 * because it will be recomputed and added
-                                 * on transmission
-                                 */
-                                if (skb->len < (iterator._max_length + FCS_LEN))
-                                        return false;
-
-                                skb_trim(skb, skb->len - FCS_LEN);
-                        }
-                        if (*iterator.this_arg & IEEE80211_RADIOTAP_F_WEP)
-                                info->flags &= ~IEEE80211_TX_INTFL_DONT_ENCRYPT;
-                        if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FRAG)
-                                info->flags &= ~IEEE80211_TX_CTL_DONTFRAG;
-                        break;
-
-                case IEEE80211_RADIOTAP_TX_FLAGS:
-                        txflags = le16_to_cpu(get_unaligned((__le16*)
-                                                iterator.this_arg));
-                        if (txflags & IEEE80211_RADIOTAP_F_TX_NOACK)
-                                info->flags |= IEEE80211_TX_CTL_NO_ACK;
-                        break;
-
-                /*
-                 * Please update the file
-                 * Documentation/networking/mac80211-injection.txt
-                 * when parsing new fields here.
-                 */
-
-                default:
-                        break;
-                }
-        }
-
-        if (ret != -ENOENT) /* ie, if we didn't simply run out of fields */
-                return false;
-
-        /*
-         * remove the radiotap header
-         * iterator->_max_length was sanity-checked against
-         * skb->len by iterator init
-         */
-        skb_pull(skb, iterator._max_length);
-
-        return true;
-}
-
 static bool ieee80211_tx_prep_agg(struct ieee80211_tx_data *tx,
                                   struct sk_buff *skb,
                                   struct ieee80211_tx_info *info,
@@ -1205,19 +1108,6 @@ ieee80211_tx_prepare(struct ieee80211_sub_if_data *sdata,
         tx->sdata = sdata;
         tx->channel = local->hw.conf.channel;
 
-        /* process and remove the injection radiotap header */
-        if (unlikely(info->flags & IEEE80211_TX_INTFL_HAS_RADIOTAP)) {
-                if (!__ieee80211_parse_tx_radiotap(tx, skb))
-                        return TX_DROP;
-
-                /*
-                 * __ieee80211_parse_tx_radiotap has now removed
-                 * the radiotap header that was present and pre-filled
-                 * 'tx' with tx control information.
-                 */
-                info->flags &= ~IEEE80211_TX_INTFL_HAS_RADIOTAP;
-        }
-
         /*
          * If this flag is set to true anywhere, and we get here,
          * we are doing the needed processing, so remove the flag
@@ -1559,6 +1449,89 @@ void ieee80211_xmit(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
         rcu_read_unlock();
 }
 
+static bool ieee80211_parse_tx_radiotap(struct sk_buff *skb)
+{
+        struct ieee80211_radiotap_iterator iterator;
+        struct ieee80211_radiotap_header *rthdr =
+                (struct ieee80211_radiotap_header *) skb->data;
+        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+        int ret = ieee80211_radiotap_iterator_init(&iterator, rthdr, skb->len,
+                                                   NULL);
+        u16 txflags;
+
+        info->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT |
+                       IEEE80211_TX_CTL_DONTFRAG;
+
+        /*
+         * for every radiotap entry that is present
+         * (ieee80211_radiotap_iterator_next returns -ENOENT when no more
+         * entries present, or -EINVAL on error)
+         */
+
+        while (!ret) {
+                ret = ieee80211_radiotap_iterator_next(&iterator);
+
+                if (ret)
+                        continue;
+
+                /* see if this argument is something we can use */
+                switch (iterator.this_arg_index) {
+                /*
+                 * You must take care when dereferencing iterator.this_arg
+                 * for multibyte types... the pointer is not aligned.  Use
+                 * get_unaligned((type *)iterator.this_arg) to dereference
+                 * iterator.this_arg for type "type" safely on all arches.
+                */
+                case IEEE80211_RADIOTAP_FLAGS:
+                        if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FCS) {
+                                /*
+                                 * this indicates that the skb we have been
+                                 * handed has the 32-bit FCS CRC at the end...
+                                 * we should react to that by snipping it off
+                                 * because it will be recomputed and added
+                                 * on transmission
+                                 */
+                                if (skb->len < (iterator._max_length + FCS_LEN))
+                                        return false;
+
+                                skb_trim(skb, skb->len - FCS_LEN);
+                        }
+                        if (*iterator.this_arg & IEEE80211_RADIOTAP_F_WEP)
+                                info->flags &= ~IEEE80211_TX_INTFL_DONT_ENCRYPT;
+                        if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FRAG)
+                                info->flags &= ~IEEE80211_TX_CTL_DONTFRAG;
+                        break;
+
+                case IEEE80211_RADIOTAP_TX_FLAGS:
+                        txflags = get_unaligned_le16(iterator.this_arg);
+                        if (txflags & IEEE80211_RADIOTAP_F_TX_NOACK)
+                                info->flags |= IEEE80211_TX_CTL_NO_ACK;
+                        break;
+
+                /*
+                 * Please update the file
+                 * Documentation/networking/mac80211-injection.txt
+                 * when parsing new fields here.
+                 */
+
+                default:
+                        break;
+                }
+        }
+
+        if (ret != -ENOENT) /* ie, if we didn't simply run out of fields */
+                return false;
+
+        /*
+         * remove the radiotap header
+         * iterator->_max_length was sanity-checked against
+         * skb->len by iterator init
+         */
+        skb_pull(skb, iterator._max_length);
+
+        return true;
+}
+
 netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb,
                                          struct net_device *dev)
 {
@@ -1646,8 +1619,11 @@ netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb,
         memset(info, 0, sizeof(*info));
 
         info->flags = IEEE80211_TX_CTL_REQ_TX_STATUS |
-                      IEEE80211_TX_CTL_INJECTED |
-                      IEEE80211_TX_INTFL_HAS_RADIOTAP;
+                      IEEE80211_TX_CTL_INJECTED;
+
+        /* process and remove the injection radiotap header */
+        if (!ieee80211_parse_tx_radiotap(skb))
+                goto fail;
 
         rcu_read_lock();
 
@@ -1674,7 +1650,6 @@ netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb,
                 }
         }
 
-        /* pass the radiotap header up to xmit */
         ieee80211_xmit(sdata, skb);
         rcu_read_unlock();