mac80211: move TX station pointer and restructure TX

Remove the control.sta pointer from ieee80211_tx_info to free up
sufficient space in the TX skb control buffer for the upcoming
Transmit Power Control (TPC).
Instead, the pointer is now on the stack in a new control struct
that is passed as a function parameter to the drivers' tx method.

Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de>
Signed-off-by: Alina Friedrichsen <x-alina@gmx.net>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
[reworded commit message]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 15 insertions, 5 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index d67d3bbe21c1..8114f590f715 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -527,9 +527,6 @@ struct ieee80211_tx_rate {
  *  (2) driver internal use (if applicable)
  *  (3) TX status information - driver tells mac80211 what happened
  *
- * The TX control's sta pointer is only valid during the ->tx call,
- * it may be NULL.
- *
  * @flags: transmit info flags, defined above
  * @band: the band to transmit on (use for checking for races)
  * @hw_queue: HW queue to put the frame on, skb_get_queue_mapping() gives the AC
@@ -560,6 +557,7 @@ struct ieee80211_tx_info {
                                         struct ieee80211_tx_rate rates[
                                                 IEEE80211_TX_MAX_RATES];
                                         s8 rts_cts_rate_idx;
+                                        /* 3 bytes free */
                                 };
                                 /* only needed before rate control */
                                 unsigned long jiffies;
@@ -567,7 +565,7 @@ struct ieee80211_tx_info {
                         /* NB: vif can be NULL for injected frames */
                         struct ieee80211_vif *vif;
                         struct ieee80211_key_conf *hw_key;
-                        struct ieee80211_sta *sta;
+                        /* 8 bytes free */
                 } control;
                 struct {
                         struct ieee80211_tx_rate rates[IEEE80211_TX_MAX_RATES];
@@ -1079,6 +1077,16 @@ enum sta_notify_cmd {
 };
 
 /**
+ * struct ieee80211_tx_control - TX control data
+ *
+ * @sta: station table entry, this sta pointer may be NULL and
+ *      it is not allowed to copy the pointer, due to RCU.
+ */
+struct ieee80211_tx_control {
+        struct ieee80211_sta *sta;
+};
+
+/**
  * enum ieee80211_hw_flags - hardware flags
  *
  * These flags are used to indicate hardware capabilities to
@@ -2269,7 +2277,9 @@ enum ieee80211_rate_control_changed {
  *      The callback is optional and can (should!) sleep.
  */
 struct ieee80211_ops {
-        void (*tx)(struct ieee80211_hw *hw, struct sk_buff *skb);
+        void (*tx)(struct ieee80211_hw *hw,
+                   struct ieee80211_tx_control *control,
+                   struct sk_buff *skb);
         int (*start)(struct ieee80211_hw *hw);
         void (*stop)(struct ieee80211_hw *hw);
 #ifdef CONFIG_PM