cfg80211/mac80211: allow management TX to not wait for ACK

For probe responses it can be useful to not wait for ACK to
avoid retransmissions if the station that sent the probe is
already on the next channel, so allow userspace to request
not caring about the ACK with a new nl80211 flag.

Since mac80211 needs to be updated for the new function
prototype anyway implement it right away -- it's just a
few lines of code.

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

1 files changed, 24 insertions, 15 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 5b659068b020..0ef09415c89a 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -196,6 +196,7 @@ static const struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] = {
 	[NL80211_ATTR_TDLS_OPERATION] = { .type = NLA_U8 },
 	[NL80211_ATTR_TDLS_SUPPORT] = { .type = NLA_FLAG },
 	[NL80211_ATTR_TDLS_EXTERNAL_SETUP] = { .type = NLA_FLAG },
+	[NL80211_ATTR_DONT_WAIT_FOR_ACK] = { .type = NLA_FLAG },
 };
 
 /* policy for the key attributes */
@@ -5282,10 +5283,11 @@ static int nl80211_tx_mgmt(struct sk_buff *skb, struct genl_info *info)
 	int err;
 	void *hdr;
 	u64 cookie;
-	struct sk_buff *msg;
+	struct sk_buff *msg = NULL;
 	unsigned int wait = 0;
-	bool offchan;
-	bool no_cck;
+	bool offchan, no_cck, dont_wait_for_ack;
+
+	dont_wait_for_ack = info->attrs[NL80211_ATTR_DONT_WAIT_FOR_ACK];
 
 	if (!info->attrs[NL80211_ATTR_FRAME] ||
 	    !info->attrs[NL80211_ATTR_WIPHY_FREQ])
@@ -5329,29 +5331,36 @@ static int nl80211_tx_mgmt(struct sk_buff *skb, struct genl_info *info)
 	if (chan == NULL)
 		return -EINVAL;
 
-	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
-	if (!msg)
-		return -ENOMEM;
+	if (!dont_wait_for_ack) {
+		msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+		if (!msg)
+			return -ENOMEM;
 
-	hdr = nl80211hdr_put(msg, info->snd_pid, info->snd_seq, 0,
-			     NL80211_CMD_FRAME);
+		hdr = nl80211hdr_put(msg, info->snd_pid, info->snd_seq, 0,
+				     NL80211_CMD_FRAME);
 
-	if (IS_ERR(hdr)) {
-		err = PTR_ERR(hdr);
-		goto free_msg;
+		if (IS_ERR(hdr)) {
+			err = PTR_ERR(hdr);
+			goto free_msg;
+		}
 	}
+
 	err = cfg80211_mlme_mgmt_tx(rdev, dev, chan, offchan, channel_type,
 				    channel_type_valid, wait,
 				    nla_data(info->attrs[NL80211_ATTR_FRAME]),
 				    nla_len(info->attrs[NL80211_ATTR_FRAME]),
-				    no_cck, &cookie);
+				    no_cck, dont_wait_for_ack, &cookie);
 	if (err)
 		goto free_msg;
 
-	NLA_PUT_U64(msg, NL80211_ATTR_COOKIE, cookie);
+	if (msg) {
+		NLA_PUT_U64(msg, NL80211_ATTR_COOKIE, cookie);
 
-	genlmsg_end(msg, hdr);
-	return genlmsg_reply(msg, info);
+		genlmsg_end(msg, hdr);
+		return genlmsg_reply(msg, info);
+	}
+
+	return 0;
 
  nla_put_failure:
 	err = -ENOBUFS;