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

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

The original issue is the chromium issue:
http://code.google.com/p/chromium-os/issues/detail?id=11485

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

Since this change is for ChromeOs and will affect Android P2P function,
so we add config option MAC80211_SCAN_ABORT for it.

Bug 1051830

Change-Id: I77504f4d279f3f3d99b5e5f9d734480888d62193
Signed-off-by: Wei Ni <wni@nvidia.com>
Reviewed-on: http://git-master/r/160777
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Rhyland Klein <rklein@nvidia.com>
Reviewed-by: Bibhay Ranjan <bibhayr@nvidia.com>
Tested-by: Bibhay Ranjan <bibhayr@nvidia.com>
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>

4 files changed, 71 insertions, 0 deletions

diff --git a/net/mac80211/Kconfig b/net/mac80211/Kconfig
index 96ddb72760b9..778f88d75741 100644
--- a/net/mac80211/Kconfig
+++ b/net/mac80211/Kconfig
@@ -247,3 +247,12 @@ config MAC80211_DEBUG_COUNTERS
 	  and show them in debugfs.
 
 	  If unsure, say N.
+
+config MAC80211_SCAN_ABORT
+	bool "Support to abort a scan request on tx"
+	depends on MAC80211
+	depends on WIRELESS
+	default n
+	---help---
+	  Add support for aborting scan requests.
+	  This is only for ChromeOs, because it will affect Android P2P.
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index db8fae51714c..a68ef6219833 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -808,6 +808,10 @@ enum {
  * @SCAN_SUSPEND: Suspend the scan and go back to operating channel to
  *	send out data
  * @SCAN_RESUME: Resume the scan and scan the next channel
+ * @SCAN_ABORT: Abnormally terminate the scan operation, set only when
+ *	on the operating channel.
+ * @SCAN_SUSPEND_ABORT: Return to the operating channel then
+ *	terminate the scan operation.
  */
 enum mac80211_scan_state {
 	SCAN_DECISION,
@@ -815,6 +819,8 @@ enum mac80211_scan_state {
 	SCAN_SEND_PROBE,
 	SCAN_SUSPEND,
 	SCAN_RESUME,
+	SCAN_ABORT,
+	SCAN_SUSPEND_ABORT,
 };
 
 struct ieee80211_local {
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index c70e17677135..9f8412c48960 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -487,6 +487,9 @@ 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;
+#ifdef CONFIG_MAC80211_SCAN_ABORT
+	enum mac80211_scan_state next_scan_state;
+#endif
 
 	/*
 	 * check if at least one STA interface is associated,
@@ -545,10 +548,31 @@ static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 			usecs_to_jiffies(min_beacon_int * 1024) *
 			local->hw.conf.listen_interval);
 
+#ifndef CONFIG_MAC80211_SCAN_ABORT
 	if (associated && (!tx_empty || bad_latency || listen_int_exceeded))
 		local->next_scan_state = SCAN_SUSPEND;
 	else
 		local->next_scan_state = SCAN_SET_CHANNEL;
+#else
+	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_SUSPEND_ABORT;
+		} else
+			next_scan_state = SCAN_SUSPEND;
+	} else if (associated && (bad_latency || listen_int_exceeded))
+		next_scan_state = SCAN_SUSPEND;
+	else
+		next_scan_state = SCAN_SET_CHANNEL;
+
+	local->next_scan_state = next_scan_state;
+#endif
 
 	*next_delay = 0;
 }
@@ -636,9 +660,20 @@ static void ieee80211_scan_state_suspend(struct ieee80211_local *local,
 	 */
 	ieee80211_offchannel_return(local, false);
 
+#ifndef CONFIG_MAC80211_SCAN_ABORT
 	*next_delay = HZ / 5;
 	/* afterwards, resume scan & go to next channel */
 	local->next_scan_state = SCAN_RESUME;
+#else
+	if (local->next_scan_state == SCAN_SUSPEND) {
+		*next_delay = HZ / 5;
+		/* afterwards, resume scan & go to next channel */
+		local->next_scan_state = SCAN_RESUME;
+	} else {
+		*next_delay = 0;
+		local->next_scan_state = SCAN_ABORT;
+	}
+#endif
 }
 
 static void ieee80211_scan_state_resume(struct ieee80211_local *local,
@@ -731,11 +766,19 @@ void ieee80211_scan_work(struct work_struct *work)
 			ieee80211_scan_state_send_probe(local, &next_delay);
 			break;
 		case SCAN_SUSPEND:
+#ifdef CONFIG_MAC80211_SCAN_ABORT
+		case SCAN_SUSPEND_ABORT:
+#endif
 			ieee80211_scan_state_suspend(local, &next_delay);
 			break;
 		case SCAN_RESUME:
 			ieee80211_scan_state_resume(local, &next_delay);
 			break;
+#ifdef CONFIG_MAC80211_SCAN_ABORT
+		case SCAN_ABORT:
+			aborted = true;
+			goto out_complete;
+#endif
 		}
 	} while (next_delay == 0);
 
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index e0e655b4b80a..4371ed4729d5 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -136,6 +136,9 @@ 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 },
+#ifdef CONFIG_MAC80211_SCAN_ABORT
+	[NL80211_ATTR_SCAN_FLAGS] = { .type = NLA_U32 },
+#endif
 	[NL80211_ATTR_SCAN_FREQUENCIES] = { .type = NLA_NESTED },
 	[NL80211_ATTR_SCAN_SSIDS] = { .type = NLA_NESTED },
 
@@ -3867,6 +3870,12 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
 	request->no_cck =
 		nla_get_flag(info->attrs[NL80211_ATTR_TX_NO_CCK_RATE]);
 
+#ifdef CONFIG_MAC80211_SCAN_ABORT
+	if (info->attrs[NL80211_ATTR_SCAN_FLAGS])
+		request->flags = nla_get_u32(
+		    info->attrs[NL80211_ATTR_SCAN_FLAGS]);
+#endif
+
 	request->dev = dev;
 	request->wiphy = &rdev->wiphy;
 
@@ -6923,6 +6932,10 @@ static int nl80211_add_scan_req(struct sk_buff *msg,
 	if (req->ie)
 		NLA_PUT(msg, NL80211_ATTR_IE, req->ie_len, req->ie);
 
+#ifdef CONFIG_MAC80211_SCAN_ABORT
+	NLA_PUT_U32(msg, NL80211_ATTR_SCAN_FLAGS, req->flags);
+#endif
+
 	return 0;
  nla_put_failure:
 	return -ENOBUFS;