mac80211 & nl80211: add support to abort a scan request on tx

This fix comes from:
https://gerrit.chromium.org/gerrit/#change,5744
https://gerrit.chromium.org/gerrit/#change,5745

So that it can work with the related wpa_supplicant tool.

BUG=895591

Change-Id: Ie81f6d6052bd45dab13c936f9f0c5f4eb277496a
Original-Signed-off-by: Wei Ni <wni@nvidia.com>
Signed-off-by: Rhyland Klein <rklein@nvidia.com>
Reviewed-on: http://git-master/r/111333
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>

3 files changed, 53 insertions, 10 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 9fab144cc9f5..8624f27441f2 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -718,6 +718,10 @@ enum {
  *	about us leaving the channel and stop all associated STA interfaces
  * @SCAN_ENTER_OPER_CHANNEL: Enter the operating channel again, notify the
  *	AP about us being back and restart all associated STA interfaces
+ * @SCAN_ABORT: Abnormally terminate the scan operation, set only when
+ *	on the operating channel
+ * @SCAN_ENTER_OPER_CHANNEL_ABORT: Return to the operating channel then
+ *	terminate the scan operation
  */
 enum mac80211_scan_state {
 	SCAN_DECISION,
@@ -725,6 +729,8 @@ enum mac80211_scan_state {
 	SCAN_SEND_PROBE,
 	SCAN_LEAVE_OPER_CHANNEL,
 	SCAN_ENTER_OPER_CHANNEL,
+	SCAN_ABORT,
+	SCAN_ENTER_OPER_CHANNEL_ABORT,
 };
 
 struct ieee80211_local {
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 6f09eca01112..4aa2cec04f31 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -477,6 +477,7 @@ static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 	unsigned long min_beacon_int = 0;
 	struct ieee80211_sub_if_data *sdata;
 	struct ieee80211_channel *next_chan;
+	enum mac80211_scan_state next_scan_state;
 
 	/*
 	 * check if at least one STA interface is associated,
@@ -512,13 +513,21 @@ static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 		/* We're currently on operating channel. */
 		if (next_chan == local->oper_channel)
 			/* We don't need to move off of operating channel. */
-			local->next_scan_state = SCAN_SET_CHANNEL;
-		else
+			next_scan_state = SCAN_SET_CHANNEL;
+		else {
 			/*
 			 * We do need to leave operating channel, as next
-			 * scan is somewhere else.
+			 * scan is somewhere else, unless
+			 * there is pending traffic and the scan request is
+			 * marked to abort when this happens
 			 */
-			local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
+			if (associated && !tx_empty &&
+			    (local->scan_req->flags &
+				CFG80211_SCAN_FLAG_TX_ABORT))
+				next_scan_state = SCAN_ABORT;
+			else
+				next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
+		}
 	} else {
 		/*
 		 * we're currently scanning a different channel, let's
@@ -547,12 +556,24 @@ static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 				usecs_to_jiffies(min_beacon_int * 1024) *
 				local->hw.conf.listen_interval);
 
-		if (associated && ( !tx_empty || bad_latency ||
-		    listen_int_exceeded))
-			local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
+		if (associated && !tx_empty) {
+			if (unlikely(local->scan_req->flags &
+				CFG80211_SCAN_FLAG_TX_ABORT)) {
+				/*
+				 * Scan request is marked to abort when there
+				 * is outbound traffic.  Mark state to return
+				 * the operating channel and then abort.  This
+				 * happens as soon as possible.
+				 */
+				next_scan_state = SCAN_ENTER_OPER_CHANNEL_ABORT;
+			} else
+				next_scan_state = SCAN_ENTER_OPER_CHANNEL;
+		} else if (associated && (bad_latency || listen_int_exceeded))
+			next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 		else
-			local->next_scan_state = SCAN_SET_CHANNEL;
+			next_scan_state = SCAN_SET_CHANNEL;
 	}
+	local->next_scan_state = next_scan_state;
 
 	*next_delay = 0;
 }
@@ -596,8 +617,13 @@ static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *loca
 	 */
 	ieee80211_offchannel_return(local, true, false);
 
-	*next_delay = HZ / 5;
-	local->next_scan_state = SCAN_DECISION;
+	if (local->next_scan_state == SCAN_ENTER_OPER_CHANNEL) {
+		*next_delay = HZ / 5;
+		local->next_scan_state = SCAN_DECISION;
+	} else {
+		*next_delay = 0;
+		local->next_scan_state = SCAN_ABORT;
+	}
 }
 
 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
@@ -741,11 +767,15 @@ void ieee80211_scan_work(struct work_struct *work)
 			ieee80211_scan_state_send_probe(local, &next_delay);
 			break;
 		case SCAN_LEAVE_OPER_CHANNEL:
+		case SCAN_ENTER_OPER_CHANNEL_ABORT:
 			ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 			break;
 		case SCAN_ENTER_OPER_CHANNEL:
 			ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 			break;
+		case SCAN_ABORT:
+			aborted = true;
+			goto out_complete;
 		}
 	} while (next_delay == 0);
 
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index d7b91a351f84..84400e3a17b6 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -131,6 +131,7 @@ static const struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] = {
 	[NL80211_ATTR_MGMT_SUBTYPE] = { .type = NLA_U8 },
 	[NL80211_ATTR_IE] = { .type = NLA_BINARY,
 			      .len = IEEE80211_MAX_DATA_LEN },
+	[NL80211_ATTR_SCAN_FLAGS] = { .type = NLA_U32 },
 	[NL80211_ATTR_SCAN_FREQUENCIES] = { .type = NLA_NESTED },
 	[NL80211_ATTR_SCAN_SSIDS] = { .type = NLA_NESTED },
 
@@ -3457,6 +3458,10 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
 		       request->ie_len);
 	}
 
+	if (info->attrs[NL80211_ATTR_SCAN_FLAGS])
+		request->flags = nla_get_u32(
+			info->attrs[NL80211_ATTR_SCAN_FLAGS]);
+
 	for (i = 0; i < IEEE80211_NUM_BANDS; i++)
 		if (wiphy->bands[i])
 			request->rates[i] =
@@ -6158,6 +6163,8 @@ static int nl80211_add_scan_req(struct sk_buff *msg,
 	if (req->ie)
 		NLA_PUT(msg, NL80211_ATTR_IE, req->ie_len, req->ie);
 
+	NLA_PUT_U8(msg, NL80211_ATTR_SCAN_FLAGS, req->flags);
+
 	return 0;
  nla_put_failure:
 	return -ENOBUFS;