mac80211: add support for tx to abort low priority scan requests

Use NL80211_SCAN_FLAG_LOW_PRIORITY flag in mac80211's scan state
machine to prematurely terminate scan operations if outbound
traffic collides. This is useful for marking background scans so
they don't affect throughput.

Signed-off-by: Sam Leffler <sleffler@chromium.org>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
[set feature flag only if software scan is used]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 22 insertions, 4 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 6327816790e6..02e47930964f 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -866,6 +866,7 @@ 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: Abort the scan and go back to operating channel
  */
 enum mac80211_scan_state {
         SCAN_DECISION,
@@ -873,6 +874,7 @@ enum mac80211_scan_state {
         SCAN_SEND_PROBE,
         SCAN_SUSPEND,
         SCAN_RESUME,
+        SCAN_ABORT,
 };
 
 struct ieee80211_local {
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 931f14f3281f..ba5a23249771 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -602,6 +602,9 @@ struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
                            NL80211_FEATURE_SAE |
                            NL80211_FEATURE_HT_IBSS;
 
+        if (!ops->hw_scan)
+                wiphy->features |= NL80211_FEATURE_LOW_PRIORITY_SCAN;
+
         if (!ops->set_key)
                 wiphy->flags |= WIPHY_FLAG_IBSS_RSN;
 
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 987c75d46bc0..13d23299e696 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -466,6 +466,7 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
                         sizeof(*local->hw_scan_req) +
                         req->n_channels * sizeof(req->channels[0]);
                 local->hw_scan_req->ie = ies;
+                local->hw_scan_req->flags = req->flags;
 
                 local->hw_scan_band = 0;
 
@@ -566,6 +567,7 @@ 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,
@@ -624,10 +626,18 @@ 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_SUSPEND;
-        else
-                local->next_scan_state = SCAN_SET_CHANNEL;
+        if (associated && !tx_empty) {
+                if (local->scan_req->flags & NL80211_SCAN_FLAG_LOW_PRIORITY)
+                        next_scan_state = SCAN_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;
 
         *next_delay = 0;
 }
@@ -798,6 +808,9 @@ void ieee80211_scan_work(struct work_struct *work)
                 case SCAN_RESUME:
                         ieee80211_scan_state_resume(local, &next_delay);
                         break;
+                case SCAN_ABORT:
+                        aborted = true;
+                        goto out_complete;
                 }
         } while (next_delay == 0);