mac80211: make software rate control optional

Some devices implement the entire rate control in
firmware in some way, like wl1271 or like iwlwifi
which does some things in software but not a lot.
Therefore generic software rate control is rather
useless for them and just adds avoidable overhead
to the transmit path.

It's fairly simple to let drivers indicate that
they do not need rate control, but they need to
fulfil a number of conditions that we encode in
WARN_ONs.

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

1 files changed, 22 insertions, 7 deletions

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index aa017a56afc..71f370dd24b 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -148,8 +148,10 @@ struct sta_info *sta_info_get_by_idx(struct ieee80211_sub_if_data *sdata,
 static void __sta_info_free(struct ieee80211_local *local,
                             struct sta_info *sta)
 {
-        rate_control_free_sta(sta);
-        rate_control_put(sta->rate_ctrl);
+        if (sta->rate_ctrl) {
+                rate_control_free_sta(sta);
+                rate_control_put(sta->rate_ctrl);
+        }
 
 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
         printk(KERN_DEBUG "%s: Destroyed STA %pM\n",
@@ -277,6 +279,23 @@ static void sta_unblock(struct work_struct *wk)
                 ieee80211_sta_ps_deliver_poll_response(sta);
 }
 
+static int sta_prepare_rate_control(struct ieee80211_local *local,
+                                    struct sta_info *sta, gfp_t gfp)
+{
+        if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
+                return 0;
+
+        sta->rate_ctrl = rate_control_get(local->rate_ctrl);
+        sta->rate_ctrl_priv = rate_control_alloc_sta(sta->rate_ctrl,
+                                                     &sta->sta, gfp);
+        if (!sta->rate_ctrl_priv) {
+                rate_control_put(sta->rate_ctrl);
+                return -ENOMEM;
+        }
+
+        return 0;
+}
+
 struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
                                 u8 *addr, gfp_t gfp)
 {
@@ -296,11 +315,7 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
         sta->local = local;
         sta->sdata = sdata;
 
-        sta->rate_ctrl = rate_control_get(local->rate_ctrl);
-        sta->rate_ctrl_priv = rate_control_alloc_sta(sta->rate_ctrl,
-                                                     &sta->sta, gfp);
-        if (!sta->rate_ctrl_priv) {
-                rate_control_put(sta->rate_ctrl);
+        if (sta_prepare_rate_control(local, sta, gfp)) {
                 kfree(sta);
                 return NULL;
         }