cfg80211: add channel switch started notification

Add a new NL80211_CH_SWITCH_STARTED_NOTIFY message that can be sent to
the userspace when a channel switch process has started.  This allows
userspace to take action, for instance, by requesting other interfaces
to switch channel as necessary.

This patch introduces a function that allows the drivers to send this
notification.  It should be used when the driver starts processing a
channel switch initiated by a remote device (eg. when a STA receives a
CSA from the AP) and when it successfully starts a userspace-triggered
channel switch (eg. when hostapd triggers a channel swith in the AP).

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

2 files changed, 41 insertions, 3 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 24549cbe0b54..24fd2925b281 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -11653,7 +11653,9 @@ EXPORT_SYMBOL(cfg80211_pmksa_candidate_notify);
 static void nl80211_ch_switch_notify(struct cfg80211_registered_device *rdev,
                                      struct net_device *netdev,
                                      struct cfg80211_chan_def *chandef,
-                                     gfp_t gfp)
+                                     gfp_t gfp,
+                                     enum nl80211_commands notif,
+                                     u8 count)
 {
         struct sk_buff *msg;
         void *hdr;
@@ -11662,7 +11664,7 @@ static void nl80211_ch_switch_notify(struct cfg80211_registered_device *rdev,
         if (!msg)
                 return;
 
-        hdr = nl80211hdr_put(msg, 0, 0, 0, NL80211_CMD_CH_SWITCH_NOTIFY);
+        hdr = nl80211hdr_put(msg, 0, 0, 0, notif);
         if (!hdr) {
                 nlmsg_free(msg);
                 return;
@@ -11674,6 +11676,10 @@ static void nl80211_ch_switch_notify(struct cfg80211_registered_device *rdev,
         if (nl80211_send_chandef(msg, chandef))
                 goto nla_put_failure;
 
+        if ((notif == NL80211_CMD_CH_SWITCH_STARTED_NOTIFY) &&
+            (nla_put_u32(msg, NL80211_ATTR_CH_SWITCH_COUNT, count)))
+                        goto nla_put_failure;
+
         genlmsg_end(msg, hdr);
 
         genlmsg_multicast_netns(&nl80211_fam, wiphy_net(&rdev->wiphy), msg, 0,
@@ -11704,10 +11710,26 @@ void cfg80211_ch_switch_notify(struct net_device *dev,
 
         wdev->chandef = *chandef;
         wdev->preset_chandef = *chandef;
-        nl80211_ch_switch_notify(rdev, dev, chandef, GFP_KERNEL);
+        nl80211_ch_switch_notify(rdev, dev, chandef, GFP_KERNEL,
+                                 NL80211_CMD_CH_SWITCH_NOTIFY, 0);
 }
 EXPORT_SYMBOL(cfg80211_ch_switch_notify);
 
+void cfg80211_ch_switch_started_notify(struct net_device *dev,
+                                       struct cfg80211_chan_def *chandef,
+                                       u8 count)
+{
+        struct wireless_dev *wdev = dev->ieee80211_ptr;
+        struct wiphy *wiphy = wdev->wiphy;
+        struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
+
+        trace_cfg80211_ch_switch_started_notify(dev, chandef);
+
+        nl80211_ch_switch_notify(rdev, dev, chandef, GFP_KERNEL,
+                                 NL80211_CMD_CH_SWITCH_STARTED_NOTIFY, count);
+}
+EXPORT_SYMBOL(cfg80211_ch_switch_started_notify);
+
 void cfg80211_cqm_txe_notify(struct net_device *dev,
                              const u8 *peer, u32 num_packets,
                              u32 rate, u32 intvl, gfp_t gfp)
diff --git a/net/wireless/trace.h b/net/wireless/trace.h
index 277a85df910e..6e25370d3ce7 100644
--- a/net/wireless/trace.h
+++ b/net/wireless/trace.h
@@ -2355,6 +2355,22 @@ TRACE_EVENT(cfg80211_ch_switch_notify,
                   NETDEV_PR_ARG, CHAN_DEF_PR_ARG)
 );
 
+TRACE_EVENT(cfg80211_ch_switch_started_notify,
+        TP_PROTO(struct net_device *netdev,
+                 struct cfg80211_chan_def *chandef),
+        TP_ARGS(netdev, chandef),
+        TP_STRUCT__entry(
+                NETDEV_ENTRY
+                CHAN_DEF_ENTRY
+        ),
+        TP_fast_assign(
+                NETDEV_ASSIGN;
+                CHAN_DEF_ASSIGN(chandef);
+        ),
+        TP_printk(NETDEV_PR_FMT ", " CHAN_DEF_PR_FMT,
+                  NETDEV_PR_ARG, CHAN_DEF_PR_ARG)
+);
+
 TRACE_EVENT(cfg80211_radar_event,
         TP_PROTO(struct wiphy *wiphy, struct cfg80211_chan_def *chandef),
         TP_ARGS(wiphy, chandef),