mac80211: introduce flush operation

We've long lacked a good confirmation that frames
have really gone out, e.g. before going off-channel
for a scan. Add a flush() operation that drivers
can implement to provide that confirmation, and use
it in a few places:
 * before scanning sends the nullfunc frames
 * after scanning sends the nullfunc frames, if any
 * when going idle, to send any pending frames

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

diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 718a5f1..4dee69a 100644 (file)
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -896,6 +896,16 @@ static int mac80211_hwsim_ampdu_action(struct ieee80211_hw *hw,
        return 0;
 }
 
+static void mac80211_hwsim_flush(struct ieee80211_hw *hw, bool drop)
+{
+       /*
+        * In this special case, there's nothing we need to
+        * do because hwsim does transmission synchronously.
+        * In the future, when it does transmissions via
+        * userspace, we may need to do something.
+        */
+}
+
 
 static const struct ieee80211_ops mac80211_hwsim_ops =
 {
@@ -912,6 +922,7 @@ static const struct ieee80211_ops mac80211_hwsim_ops =
        .conf_tx = mac80211_hwsim_conf_tx,
        CFG80211_TESTMODE_CMD(mac80211_hwsim_testmode_cmd)
        .ampdu_action = mac80211_hwsim_ampdu_action,
+       .flush = mac80211_hwsim_flush,
 };
 
 

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 494ac69..77ea34b 100644 (file)
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1545,6 +1545,10 @@ enum ieee80211_ampdu_mlme_action {
  *     and need to call wiphy_rfkill_set_hw_state() in the callback.
  *
  * @testmode_cmd: Implement a cfg80211 test mode command.
+ *
+ * @flush: Flush all pending frames from the hardware queue, making sure
+ *     that the hardware queues are empty. If the parameter @drop is set
+ *     to %true, pending frames may be dropped.
  */
 struct ieee80211_ops {
        int (*tx)(struct ieee80211_hw *hw, struct sk_buff *skb);
@@ -1601,6 +1605,7 @@ struct ieee80211_ops {
 #ifdef CONFIG_NL80211_TESTMODE
        int (*testmode_cmd)(struct ieee80211_hw *hw, void *data, int len);
 #endif
+       void (*flush)(struct ieee80211_hw *hw, bool drop);
 };
 
 /**

diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
index 727e4cf..cbe133b 100644 (file)
--- a/net/mac80211/driver-ops.h
+++ b/net/mac80211/driver-ops.h
@@ -259,4 +259,11 @@ static inline void drv_rfkill_poll(struct ieee80211_local *local)
        if (local->ops->rfkill_poll)
                local->ops->rfkill_poll(&local->hw);
 }
+
+static inline void drv_flush(struct ieee80211_local *local, bool drop)
+{
+       trace_drv_flush(local, drop);
+       if (local->ops->flush)
+               local->ops->flush(&local->hw, drop);
+}
 #endif /* __MAC80211_DRIVER_OPS */

diff --git a/net/mac80211/driver-trace.h b/net/mac80211/driver-trace.h
index 7a849b9..977cc75 100644 (file)
--- a/net/mac80211/driver-trace.h
+++ b/net/mac80211/driver-trace.h
@@ -690,6 +690,27 @@ TRACE_EVENT(drv_ampdu_action,
                LOCAL_PR_ARG, VIF_PR_ARG, STA_PR_ARG, __entry->action, __entry->tid, __entry->ret
        )
 );
+
+TRACE_EVENT(drv_flush,
+       TP_PROTO(struct ieee80211_local *local, bool drop),
+
+       TP_ARGS(local, drop),
+
+       TP_STRUCT__entry(
+               LOCAL_ENTRY
+               __field(bool, drop)
+       ),
+
+       TP_fast_assign(
+               LOCAL_ASSIGN;
+               __entry->drop = drop;
+       ),
+
+       TP_printk(
+               LOCAL_PR_FMT " drop:%d",
+               LOCAL_PR_ARG, __entry->drop
+       )
+);
 #endif /* !__MAC80211_DRIVER_TRACE || TRACE_HEADER_MULTI_READ */
 
 #undef TRACE_INCLUDE_PATH

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 1ceca14..389dc8d 100644 (file)
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -917,6 +917,8 @@ static u32 ieee80211_idle_on(struct ieee80211_local *local)
               wiphy_name(local->hw.wiphy));
 #endif
 
+       drv_flush(local, false);
+
        local->hw.conf.flags |= IEEE80211_CONF_IDLE;
        return IEEE80211_CONF_CHANGE_IDLE;
 }

diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index ae18300..d98c45e 100644 (file)
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -418,9 +418,10 @@ static int ieee80211_start_sw_scan(struct ieee80211_local *local)
        local->next_scan_state = SCAN_DECISION;
        local->scan_channel_idx = 0;
 
+       drv_flush(local, false);
+
        ieee80211_configure_filter(local);
 
-       /* TODO: start scan as soon as all nullfunc frames are ACKed */
        ieee80211_queue_delayed_work(&local->hw,
                                     &local->scan_work,
                                     IEEE80211_CHANNEL_TIME);
@@ -584,8 +585,16 @@ static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *loca
 
        __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 
+       /*
+        * What if the nullfunc frames didn't arrive?
+        */
+       drv_flush(local, false);
+       if (local->ops->flush)
+               *next_delay = 0;
+       else
+               *next_delay = HZ / 10;
+
        /* advance to the next channel to be scanned */
-       *next_delay = HZ / 10;
        local->next_scan_state = SCAN_SET_CHANNEL;
 }