From: Johannes Berg <johannes.berg@xxxxxxxxx>
Currently the code assigns channel contexts to VLANs
(for use by the TX/RX code) when the AP master gets
its channel context assigned. This works fine, but
in the upcoming radar detection work the VLANs don't
require a channel context (during radar detection)
and assigning one to them anyway causes issues with
locking and also inconsistencies -- a VLAN interface
that is added before radar detection would get the
channel context, while one added during it wouldn't.
Fix these issues moving the channel context copying
to a new explicit operation that will not be used
in the radar detection code.
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
---
net/mac80211/cfg.c | 2 ++
net/mac80211/chan.c | 52 ++++++++++++++++++++++++++++++----------------
net/mac80211/ieee80211_i.h | 2 ++
3 files changed, 38 insertions(+), 18 deletions(-)
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 799e706..68eca17 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -933,6 +933,7 @@ static int ieee80211_start_ap(struct wiphy *wiphy, struct net_device *dev,
IEEE80211_CHANCTX_SHARED);
if (err)
return err;
+ ieee80211_vif_copy_chanctx_to_vlans(sdata, false);
/*
* Apply control port protocol, this allows us to
@@ -1047,6 +1048,7 @@ static int ieee80211_stop_ap(struct wiphy *wiphy, struct net_device *dev)
local->total_ps_buffered -= skb_queue_len(&sdata->u.ap.ps.bc_buf);
skb_queue_purge(&sdata->u.ap.ps.bc_buf);
+ ieee80211_vif_copy_chanctx_to_vlans(sdata, true);
ieee80211_vif_release_channel(sdata);
return 0;
diff --git a/net/mac80211/chan.c b/net/mac80211/chan.c
index ad35185..bf10da6 100644
--- a/net/mac80211/chan.c
+++ b/net/mac80211/chan.c
@@ -211,15 +211,6 @@ static void __ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
ctx = container_of(conf, struct ieee80211_chanctx, conf);
- if (sdata->vif.type == NL80211_IFTYPE_AP) {
- struct ieee80211_sub_if_data *vlan;
-
- /* for the VLAN list */
- ASSERT_RTNL();
- list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list)
- rcu_assign_pointer(vlan->vif.chanctx_conf, NULL);
- }
-
ieee80211_unassign_vif_chanctx(sdata, ctx);
if (ctx->refcount == 0)
ieee80211_free_chanctx(local, ctx);
@@ -339,15 +330,6 @@ int ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
goto out;
}
- if (sdata->vif.type == NL80211_IFTYPE_AP) {
- struct ieee80211_sub_if_data *vlan;
-
- /* for the VLAN list */
- ASSERT_RTNL();
- list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list)
- rcu_assign_pointer(vlan->vif.chanctx_conf, &ctx->conf);
- }
-
ieee80211_recalc_smps_chanctx(local, ctx);
out:
mutex_unlock(&local->chanctx_mtx);
@@ -430,6 +412,40 @@ void ieee80211_vif_vlan_copy_chanctx(struct ieee80211_sub_if_data *sdata)
mutex_unlock(&local->chanctx_mtx);
}
+void ieee80211_vif_copy_chanctx_to_vlans(struct ieee80211_sub_if_data *sdata,
+ bool clear)
+{
+ struct ieee80211_local *local = sdata->local;
+ struct ieee80211_sub_if_data *vlan;
+ struct ieee80211_chanctx_conf *conf;
+
+ ASSERT_RTNL();
+
+ if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_AP))
+ return;
+
+ mutex_lock(&local->chanctx_mtx);
+
+ /*
+ * Check that conf exists, even when clearing this function
+ * must be called with the AP's channel context still there
+ * as it would otherwise cause VLANs to have an invalid
+ * channel context pointer for a while, possibly pointing
+ * to a channel context that has already been freed.
+ */
+ conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
+ lockdep_is_held(&local->chanctx_mtx));
+ WARN_ON(!conf);
+
+ if (clear)
+ conf = NULL;
+
+ list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list)
+ rcu_assign_pointer(vlan->vif.chanctx_conf, conf);
+
+ mutex_unlock(&local->chanctx_mtx);
+}
+
void ieee80211_iter_chan_contexts_atomic(
struct ieee80211_hw *hw,
void (*iter)(struct ieee80211_hw *hw,
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 816bebb..f016507 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1614,6 +1614,8 @@ ieee80211_vif_change_bandwidth(struct ieee80211_sub_if_data *sdata,
const struct cfg80211_chan_def *chandef);
void ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata);
void ieee80211_vif_vlan_copy_chanctx(struct ieee80211_sub_if_data *sdata);
+void ieee80211_vif_copy_chanctx_to_vlans(struct ieee80211_sub_if_data *sdata,
+ bool clear);
void ieee80211_recalc_smps_chanctx(struct ieee80211_local *local,
struct ieee80211_chanctx *chanctx);
--
1.8.0
--
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