wifi: cfg80211: add NL80211_CMD_NAN_SET_NON_EVAC_CHANNELS

Add a new NL80211_CMD_NAN_SET_NON_EVAC_CHANNELS command that lets user
space mark a set of NAN channels as non-evacuable. The command carries
the channels as nested NL80211_ATTR_NAN_CHANNEL attributes (chandef
only) and replaces the entire set of non-evacuable channels; channels
not included in the list become evacuable again.

All provided channels must already exist in the current local schedule,
otherwise -ENOENT is returned. The command is rejected with -EBUSY
while a schedule update is pending.

This prevents the kernel from evacuating channels that carry NDC or
immutable schedules, so evacuating these channels would break existing
NDP connections.

Fixes: 154b0296c0 ("wifi: nl80211: Add a notification to notify NAN channel evacuation")
Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20260921215936.2efc32011e73.Ice8839058e114f6f9783079807df446388187dda@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -4264,6 +4264,21 @@ struct cfg80211_nan_local_sched {
 	struct cfg80211_nan_channel nan_channels[] __counted_by(n_channels);
 };
 
+/**
+ * struct cfg80211_nan_non_evac_channels - NAN non-evacuable channels
+ *
+ * This struct defines the set of NAN local schedule channels that must not
+ * be evacuated for concurrent operations.
+ *
+ * @n_channels: number of channel definitions in %chandefs.
+ * @chandefs: array of channel definitions that must not be evacuated. Each
+ *	must match a channel of the current local schedule.
+ */
+struct cfg80211_nan_non_evac_channels {
+	u8 n_channels;
+	struct cfg80211_chan_def chandefs[] __counted_by(n_channels);
+};
+
 /**
  * struct cfg80211_nan_peer_map - NAN peer schedule map
  *
@@ -5212,6 +5227,12 @@ struct mgmt_frame_regs {
  *	schedule, the full new schedule is provided - partial updates are not
  *	supported, and the new schedule completely replaces the previous one.
  *
+ * @nan_set_non_evac_channels: set the list of local schedule channels that
+ *	must not be evacuated for concurrent operations. The provided list
+ *	replaces the previous set; channels of the current schedule that are
+ *	not included become evacuable again. All provided channels are
+ *	guaranteed by cfg80211 to belong to the current local schedule.
+ *
  * @set_multicast_to_unicast: configure multicast to unicast conversion for BSS
  *
  * @get_txq_stats: Get TXQ stats for interface or phy. If wdev is %NULL, this
@@ -5601,6 +5622,9 @@ struct cfg80211_ops {
 	int	(*nan_set_peer_sched)(struct wiphy *wiphy,
 				      struct wireless_dev *wdev,
 				      struct cfg80211_nan_peer_sched *sched);
+	int	(*nan_set_non_evac_channels)(struct wiphy *wiphy,
+					     struct wireless_dev *wdev,
+					     struct cfg80211_nan_non_evac_channels *channels);
 	int	(*set_multicast_to_unicast)(struct wiphy *wiphy,
 					    struct net_device *dev,
 					    const bool enabled);

include/uapi/linux/nl80211.h

@@ -1383,6 +1383,13 @@
  *	from the device to perform an announced schedule update. See
  *	%NL80211_ATTR_NAN_SCHED_DEFERRED for more details.
  *	If not set, the schedule should be applied immediately.
+ *	Setting a new schedule is always allowed and is never treated as an
+ *	evacuation, even if it removes channels that were previously marked as
+ *	non-evacuable with %NL80211_CMD_NAN_SET_NON_EVAC_CHANNELS. The
+ *	non-evacuable marking is a per-channel property of the schedule:
+ *	channels that remain in the new schedule keep their marking, channels
+ *	that are removed simply lose it, and newly added channels are
+ *	evacuable by default.
  * @NL80211_CMD_NAN_SCHED_UPDATE_DONE: Event sent to user space to notify that
  *	a deferred local NAN schedule update (requested with
  *	%NL80211_CMD_NAN_SET_LOCAL_SCHED and %NL80211_ATTR_NAN_SCHED_DEFERRED)
@@ -1427,6 +1434,28 @@
  * @NL80211_CMD_STOP_PD: Stop the PD operation, identified by
  *	its %NL80211_ATTR_WDEV interface.
  *
+ * @NL80211_CMD_NAN_SET_NON_EVAC_CHANNELS: Set the list of NAN local schedule
+ *	channels that must not be evacuated. NAN must be operational
+ *	(%NL80211_CMD_START_NAN was executed) and a local schedule must have
+ *	been set (%NL80211_CMD_NAN_SET_LOCAL_SCHED). The command carries zero
+ *	or more nested %NL80211_ATTR_NAN_CHANNEL attributes, each identifying a
+ *	channel (by its channel definition) of the current local schedule that
+ *	must not be evacuated for concurrent operations. The provided list
+ *	replaces the previous set of non-evacuable channels; channels of the
+ *	current schedule that are not included become evacuable again. All
+ *	provided channels must exist in the current local schedule, otherwise
+ *	the command fails. This is used to protect channels carrying NDC or
+ *	immutable schedules, whose evacuation would break existing NDP
+ *	connections.
+ *	The non-evacuable marking is a per-channel property of the current
+ *	local schedule and only affects evacuation for concurrent operations;
+ *	it does not prevent the schedule itself from being changed. Removing a
+ *	channel from the schedule with %NL80211_CMD_NAN_SET_LOCAL_SCHED is a
+ *	user-initiated change, not an evacuation, and is allowed even for a
+ *	non-evacuable channel. Across a schedule update, channels that remain
+ *	keep their non-evacuable marking, removed channels lose it, and newly
+ *	added channels are evacuable by default; issue this command again to
+ *	change the non-evacuable set.
  * @NL80211_CMD_MAX: highest used command number
  * @__NL80211_CMD_AFTER_LAST: internal use
  */
@@ -1705,6 +1734,8 @@ enum nl80211_commands {
 	NL80211_CMD_START_PD,
 	NL80211_CMD_STOP_PD,
 
+	NL80211_CMD_NAN_SET_NON_EVAC_CHANNELS,
+
 	/* add new commands above here */
 
 	/* used to define NL80211_CMD_MAX below */

net/wireless/core.c

@@ -348,6 +348,41 @@ int cfg80211_nan_set_local_schedule(struct cfg80211_registered_device *rdev,
 	return 0;
 }
 
+int cfg80211_nan_set_non_evac_channels(struct cfg80211_registered_device *rdev,
+				       struct wireless_dev *wdev,
+				       struct cfg80211_nan_non_evac_channels *channels)
+{
+	lockdep_assert_held(&rdev->wiphy.mtx);
+
+	if (wdev->iftype != NL80211_IFTYPE_NAN || !wdev_running(wdev))
+		return -EINVAL;
+
+	/*
+	 * Don't allow updating the non-evacuable channels while a deferred
+	 * schedule update is pending, as the set of channels may still change.
+	 */
+	if (wdev->u.nan.sched_update_pending)
+		return -EBUSY;
+
+	/* All provided channels must belong to the current local schedule. */
+	for (int i = 0; i < channels->n_channels; i++) {
+		bool found = false;
+
+		for (int j = 0; j < wdev->u.nan.n_channels; j++) {
+			if (cfg80211_chandef_identical(&wdev->u.nan.chandefs[j],
+						       &channels->chandefs[i])) {
+				found = true;
+				break;
+			}
+		}
+
+		if (!found)
+			return -ENOENT;
+	}
+
+	return rdev_nan_set_non_evac_channels(rdev, wdev, channels);
+}
+
 void cfg80211_stop_pd(struct cfg80211_registered_device *rdev,
 		      struct wireless_dev *wdev)
 {

net/wireless/core.h

@@ -578,6 +578,10 @@ int cfg80211_nan_set_local_schedule(struct cfg80211_registered_device *rdev,
 				    struct wireless_dev *wdev,
 				    struct cfg80211_nan_local_sched *sched);
 
+int cfg80211_nan_set_non_evac_channels(struct cfg80211_registered_device *rdev,
+				       struct wireless_dev *wdev,
+				       struct cfg80211_nan_non_evac_channels *channels);
+
 struct cfg80211_internal_bss *
 cfg80211_bss_update(struct cfg80211_registered_device *rdev,
 		    struct cfg80211_internal_bss *tmp,

net/wireless/nl80211.c

@@ -17845,6 +17845,69 @@ static int nl80211_nan_set_local_sched(struct sk_buff *skb,
 	return cfg80211_nan_set_local_schedule(rdev, wdev, sched);
 }
 
+static int
+nl80211_parse_non_evac_channel(struct cfg80211_registered_device *rdev,
+			       struct nlattr *channel, struct genl_info *info,
+			       struct cfg80211_chan_def *chandef)
+{
+	struct nlattr **channel_parsed __free(kfree) =
+		kcalloc(NL80211_ATTR_MAX + 1, sizeof(*channel_parsed),
+			GFP_KERNEL);
+	int ret;
+
+	if (!channel_parsed)
+		return -ENOMEM;
+
+	ret = nla_parse_nested(channel_parsed, NL80211_ATTR_MAX, channel, NULL,
+			       info->extack);
+	if (ret)
+		return ret;
+
+	return nl80211_parse_chandef(rdev, info->extack, channel_parsed,
+				     chandef, false);
+}
+
+static int nl80211_nan_set_non_evac_channels(struct sk_buff *skb,
+					     struct genl_info *info)
+{
+	struct cfg80211_registered_device *rdev = info->user_ptr[0];
+	struct wireless_dev *wdev = info->user_ptr[1];
+	int rem, i = 0, n_channels = 0;
+	struct nlattr *channel;
+
+	if (wdev->iftype != NL80211_IFTYPE_NAN)
+		return -EOPNOTSUPP;
+
+	if (!wdev_running(wdev))
+		return -ENOTCONN;
+
+	/* Count how many channel attributes we got */
+	nlmsg_for_each_attr_type(channel, NL80211_ATTR_NAN_CHANNEL,
+				 info->nlhdr, GENL_HDRLEN, rem)
+		n_channels++;
+
+	struct cfg80211_nan_non_evac_channels *channels __free(kfree) =
+		kzalloc(struct_size(channels, chandefs, n_channels),
+			GFP_KERNEL);
+	if (!channels)
+		return -ENOMEM;
+
+	channels->n_channels = n_channels;
+
+	nlmsg_for_each_attr_type(channel, NL80211_ATTR_NAN_CHANNEL,
+				 info->nlhdr, GENL_HDRLEN, rem) {
+		int ret;
+
+		ret = nl80211_parse_non_evac_channel(rdev, channel, info,
+						     &channels->chandefs[i]);
+		if (ret)
+			return ret;
+		i++;
+	}
+
+	return cfg80211_nan_set_non_evac_channels(rdev, wdev, channels);
+}
+
 static int nl80211_get_protocol_features(struct sk_buff *skb,
 					 struct genl_info *info)
 {
@@ -20724,6 +20787,12 @@ static const struct genl_small_ops nl80211_small_ops[] = {
 		.flags = GENL_ADMIN_PERM,
 		.internal_flags = IFLAGS(NL80211_FLAG_NEED_WDEV_UP),
 	},
+	{
+		.cmd = NL80211_CMD_NAN_SET_NON_EVAC_CHANNELS,
+		.doit = nl80211_nan_set_non_evac_channels,
+		.flags = GENL_ADMIN_PERM,
+		.internal_flags = IFLAGS(NL80211_FLAG_NEED_WDEV_UP),
+	},
 };
 
 static struct genl_family nl80211_fam __ro_after_init = {

net/wireless/rdev-ops.h

@@ -1097,6 +1097,23 @@ rdev_nan_set_peer_sched(struct cfg80211_registered_device *rdev,
 	return ret;
 }
 
+static inline int
+rdev_nan_set_non_evac_channels(struct cfg80211_registered_device *rdev,
+			       struct wireless_dev *wdev,
+			       struct cfg80211_nan_non_evac_channels *channels)
+{
+	int ret;
+
+	trace_rdev_nan_set_non_evac_channels(&rdev->wiphy, wdev, channels);
+	if (rdev->ops->nan_set_non_evac_channels)
+		ret = rdev->ops->nan_set_non_evac_channels(&rdev->wiphy, wdev,
+							   channels);
+	else
+		ret = -EOPNOTSUPP;
+	trace_rdev_return_int(&rdev->wiphy, ret);
+	return ret;
+}
+
 static inline int rdev_start_pd(struct cfg80211_registered_device *rdev,
 				struct wireless_dev *wdev)
 {

net/wireless/trace.h

@@ -2486,6 +2486,31 @@ TRACE_EVENT(rdev_nan_set_peer_sched,
 	)
 );
 
+TRACE_EVENT(rdev_nan_set_non_evac_channels,
+	TP_PROTO(struct wiphy *wiphy, struct wireless_dev *wdev,
+		 struct cfg80211_nan_non_evac_channels *channels),
+	TP_ARGS(wiphy, wdev, channels),
+	TP_STRUCT__entry(
+		WIPHY_ENTRY
+		WDEV_ENTRY
+		__field(u8, n_channels)
+		__dynamic_array(u32, freqs, channels->n_channels)
+	),
+	TP_fast_assign(
+		u32 *freqs = __get_dynamic_array(freqs);
+
+		WIPHY_ASSIGN;
+		WDEV_ASSIGN;
+		__entry->n_channels = channels->n_channels;
+		for (int i = 0; i < channels->n_channels; i++)
+			freqs[i] = channels->chandefs[i].chan->center_freq;
+	),
+	TP_printk(WIPHY_PR_FMT ", " WDEV_PR_FMT ", n_channels: %u, freqs: %s",
+		  WIPHY_PR_ARG, WDEV_PR_ARG, __entry->n_channels,
+		  __print_array(__get_dynamic_array(freqs),
+				__entry->n_channels, sizeof(u32)))
+);
+
 TRACE_EVENT(rdev_set_mac_acl,
 	TP_PROTO(struct wiphy *wiphy, struct net_device *netdev,
 		 struct cfg80211_acl_data *params),