[RFC 3/5] mac80211: don't overwrite QoS TID of injected frames

[Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>]

Currently ieee80211_set_qos_hdr overwrites the QoS TID of injected
frames based on the value assigned to skb->priority. The commit
753ffad3d624 ("mac80211: fix TID field in monitor mode transmit")
worked around this problem by setting skb->priority to the TID of
the injected frame, which assured the QoS TID will not be changed
to a different value. Unfortunately, this workaround complicates
the handling of injected frames because we can't set skb->priority
without affecting the TID value of injected frames.

To avoid this, and to simplify the next patch, detect if a frame is
injected in ieee80211_set_qos_hdr and if so do not change its QoS
field.

Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
---
 net/mac80211/tx.c  | 5 +----
 net/mac80211/wme.c | 8 ++++++++
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 23fa19148..96069683f 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2266,10 +2266,7 @@ netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb,
 						    payload[7]);
 	}
 
-	/*
-	 * Initialize skb->priority for QoS frames. This is put in the TID field
-	 * of the frame before passing it to the driver.
-	 */
+	/* Initialize skb->priority for QoS frames */
 	if (ieee80211_is_data_qos(hdr->frame_control)) {
 		u8 *p = ieee80211_get_qos_ctl(hdr);
 		skb->priority = *p & IEEE80211_QOS_CTL_TAG1D_MASK;
diff --git a/net/mac80211/wme.c b/net/mac80211/wme.c
index a49dd7f1f..e66d1463d 100644
--- a/net/mac80211/wme.c
+++ b/net/mac80211/wme.c
@@ -252,6 +252,14 @@ void ieee80211_set_qos_hdr(struct ieee80211_sub_if_data *sdata,
 
 	p = ieee80211_get_qos_ctl(hdr);
 
+	/* don't overwrite the QoS field of injected frames */
+	if (info->flags & IEEE80211_TX_CTL_INJECTED) {
+		/* do take into account Ack policy of injected frames */
+		if (*p & IEEE80211_QOS_CTL_ACK_POLICY_NOACK)
+			info->flags |= IEEE80211_TX_CTL_NO_ACK;
+		return;
+	}
+
 	/* set up the first byte */
 
 	/*
-- 
2.27.0