wifi: cfg80211/nl80211: Add support to indicate STA MLD setup links removal

STA MLD setup links may get removed if AP MLD remove the corresponding
affiliated APs with Multi-Link reconfiguration as described in
P802.11be_D3.0, section 35.3.6.2.2 Removing affiliated APs. Currently,
there is no support to notify such operation to cfg80211 and userspace.

Add support for the drivers to indicate STA MLD setup links removal to
cfg80211 and notify the same to userspace. Upon receiving such
indication from the driver, clear the MLO links information of the
removed links in the WDEV.

Signed-off-by: Veerendranath Jakkam <quic_vjakkam@quicinc.com>
Link: https://lore.kernel.org/r/20230317142153.237900-1-quic_vjakkam@quicinc.com
[rename function and attribute, fix kernel-doc]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

4 files changed, 101 insertions, 0 deletions

diff --git a/net/wireless/core.h b/net/wireless/core.h
index 291c6d83d56f77..8a807b609ef733 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -576,5 +576,6 @@ void cfg80211_remove_link(struct wireless_dev *wdev, unsigned int link_id);
 void cfg80211_remove_links(struct wireless_dev *wdev);
 int cfg80211_remove_virtual_intf(struct cfg80211_registered_device *rdev,
 				 struct wireless_dev *wdev);
+void cfg80211_wdev_release_link_bsses(struct wireless_dev *wdev, u16 link_mask);
 
 #endif /* __NET_WIRELESS_CORE_H */
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 7b547aeb52f1c0..0da2e6a2a7ea94 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -18288,6 +18288,76 @@ void nl80211_send_disconnected(struct cfg80211_registered_device *rdev,
 	nlmsg_free(msg);
 }
 
+void cfg80211_links_removed(struct net_device *dev, u16 link_mask)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct wiphy *wiphy = wdev->wiphy;
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
+	struct sk_buff *msg;
+	struct nlattr *links;
+	void *hdr;
+
+	ASSERT_WDEV_LOCK(wdev);
+	trace_cfg80211_links_removed(dev, link_mask);
+
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_STATION &&
+		    wdev->iftype != NL80211_IFTYPE_P2P_CLIENT))
+		return;
+
+	if (WARN_ON(!wdev->valid_links || !link_mask ||
+		    (wdev->valid_links & link_mask) != link_mask ||
+		    wdev->valid_links == link_mask))
+		return;
+
+	cfg80211_wdev_release_link_bsses(wdev, link_mask);
+	wdev->valid_links &= ~link_mask;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return;
+
+	hdr = nl80211hdr_put(msg, 0, 0, 0, NL80211_CMD_LINKS_REMOVED);
+	if (!hdr) {
+		nlmsg_free(msg);
+		return;
+	}
+
+	if (nla_put_u32(msg, NL80211_ATTR_WIPHY, rdev->wiphy_idx) ||
+	    nla_put_u32(msg, NL80211_ATTR_IFINDEX, dev->ifindex))
+		goto nla_put_failure;
+
+	links = nla_nest_start(msg, NL80211_ATTR_MLO_LINKS);
+	if (!links)
+		goto nla_put_failure;
+
+	while (link_mask) {
+		struct nlattr *link;
+		int link_id = __ffs(link_mask);
+
+		link = nla_nest_start(msg, link_id + 1);
+		if (!link)
+			goto nla_put_failure;
+
+		if (nla_put_u8(msg, NL80211_ATTR_MLO_LINK_ID, link_id))
+			goto nla_put_failure;
+
+		nla_nest_end(msg, link);
+		link_mask &= ~(1 << link_id);
+	}
+
+	nla_nest_end(msg, links);
+
+	genlmsg_end(msg, hdr);
+
+	genlmsg_multicast_netns(&nl80211_fam, wiphy_net(&rdev->wiphy), msg, 0,
+				NL80211_MCGRP_MLME, GFP_KERNEL);
+	return;
+
+ nla_put_failure:
+	nlmsg_free(msg);
+}
+EXPORT_SYMBOL(cfg80211_links_removed);
+
 void nl80211_send_ibss_bssid(struct cfg80211_registered_device *rdev,
 			     struct net_device *netdev, const u8 *bssid,
 			     gfp_t gfp)
diff --git a/net/wireless/sme.c b/net/wireless/sme.c
index 247369004aaab4..9bba233b5a6ec8 100644
--- a/net/wireless/sme.c
+++ b/net/wireless/sme.c
@@ -491,6 +491,21 @@ static void cfg80211_wdev_release_bsses(struct wireless_dev *wdev)
 	}
 }
 
+void cfg80211_wdev_release_link_bsses(struct wireless_dev *wdev, u16 link_mask)
+{
+	unsigned int link;
+
+	for_each_valid_link(wdev, link) {
+		if (!wdev->links[link].client.current_bss ||
+		    !(link_mask & BIT(link)))
+			continue;
+		cfg80211_unhold_bss(wdev->links[link].client.current_bss);
+		cfg80211_put_bss(wdev->wiphy,
+				 &wdev->links[link].client.current_bss->pub);
+		wdev->links[link].client.current_bss = NULL;
+	}
+}
+
 static int cfg80211_sme_get_conn_ies(struct wireless_dev *wdev,
 				     const u8 *ies, size_t ies_len,
 				     const u8 **out_ies, size_t *out_ies_len)
diff --git a/net/wireless/trace.h b/net/wireless/trace.h
index e63990b81249d8..617c0d0dfa963c 100644
--- a/net/wireless/trace.h
+++ b/net/wireless/trace.h
@@ -3966,6 +3966,21 @@ TRACE_EVENT(rdev_set_hw_timestamp,
 		  __entry->enable)
 );
 
+TRACE_EVENT(cfg80211_links_removed,
+	TP_PROTO(struct net_device *netdev, u16 link_mask),
+	TP_ARGS(netdev, link_mask),
+	TP_STRUCT__entry(
+		NETDEV_ENTRY
+		__field(u16, link_mask)
+	),
+	TP_fast_assign(
+		NETDEV_ASSIGN;
+		__entry->link_mask = link_mask;
+	),
+	TP_printk(NETDEV_PR_FMT ", link_mask:%u", NETDEV_PR_ARG,
+		  __entry->link_mask)
+);
+
 #endif /* !__RDEV_OPS_TRACE || TRACE_HEADER_MULTI_READ */
 
 #undef TRACE_INCLUDE_PATH