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, 11 insertions, 1 deletions

diff --git a/net/mac80211/rate.c b/net/mac80211/rate.c
index ccda7454fb1..b9007f80cb9 100644
--- a/net/mac80211/rate.c
+++ b/net/mac80211/rate.c
@@ -284,9 +284,16 @@ int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
 	struct rate_control_ref *ref, *old;
 
 	ASSERT_RTNL();
+
 	if (local->open_count)
 		return -EBUSY;
 
+	if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) {
+		if (WARN_ON(!local->ops->set_rts_threshold))
+			return -EINVAL;
+		return 0;
+	}
+
 	ref = rate_control_alloc(name, local);
 	if (!ref) {
 		printk(KERN_WARNING "%s: Failed to select rate control "
@@ -305,7 +312,6 @@ int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
 	       "algorithm '%s'\n", wiphy_name(local->hw.wiphy),
 	       ref->ops->name);
 
-
 	return 0;
 }
 
@@ -314,6 +320,10 @@ void rate_control_deinitialize(struct ieee80211_local *local)
 	struct rate_control_ref *ref;
 
 	ref = local->rate_ctrl;
+
+	if (!ref)
+		return;
+
 	local->rate_ctrl = NULL;
 	rate_control_put(ref);
 }