mac80211: allow reservation of a running chanctx
With single-channel drivers, we need to be able to change a running
chanctx if we want to use chanctx reservation. Not all drivers may be
able to do this, so add a flag that indicates support for it.
Changing a running chanctx can also be used as an optimization in
multi-channel drivers when the context needs to be reserved for future
usage.
Introduce IEEE80211_CHANCTX_RESERVED chanctx mode to mark a channel as
reserved so nobody else can use it (since we know it's going to
change). In the future, we may allow several vifs to use the same
reservation as long as they plan to use the chanctx on the same
future channel.
Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/chan.c b/net/mac80211/chan.c
index baad756..57b8ab1 100644
--- a/net/mac80211/chan.c
+++ b/net/mac80211/chan.c
@@ -168,6 +168,27 @@
}
}
+static bool ieee80211_chanctx_is_reserved(struct ieee80211_local *local,
+ struct ieee80211_chanctx *ctx)
+{
+ struct ieee80211_sub_if_data *sdata;
+ bool ret = false;
+
+ lockdep_assert_held(&local->chanctx_mtx);
+ rcu_read_lock();
+ list_for_each_entry_rcu(sdata, &local->interfaces, list) {
+ if (!ieee80211_sdata_running(sdata))
+ continue;
+ if (sdata->reserved_chanctx == ctx) {
+ ret = true;
+ break;
+ }
+ }
+
+ rcu_read_unlock();
+ return ret;
+}
+
static struct ieee80211_chanctx *
ieee80211_find_chanctx(struct ieee80211_local *local,
const struct cfg80211_chan_def *chandef,
@@ -183,7 +204,12 @@
list_for_each_entry(ctx, &local->chanctx_list, list) {
const struct cfg80211_chan_def *compat;
- if (ctx->mode == IEEE80211_CHANCTX_EXCLUSIVE)
+ /* We don't support chanctx reservation for multiple
+ * vifs yet, so don't allow reserved chanctxs to be
+ * reused.
+ */
+ if ((ctx->mode == IEEE80211_CHANCTX_EXCLUSIVE) ||
+ ieee80211_chanctx_is_reserved(local, ctx))
continue;
compat = cfg80211_chandef_compatible(&ctx->conf.def, chandef);
@@ -718,11 +744,20 @@
/* try to find another context with the chandef we want */
new_ctx = ieee80211_find_chanctx(local, chandef, mode);
if (!new_ctx) {
- /* create a new context */
- new_ctx = ieee80211_new_chanctx(local, chandef, mode);
- if (IS_ERR(new_ctx)) {
- ret = PTR_ERR(new_ctx);
- goto out;
+ if (curr_ctx->refcount == 1 &&
+ (local->hw.flags & IEEE80211_HW_CHANGE_RUNNING_CHANCTX)) {
+ /* if we're the only users of the chanctx and
+ * the driver supports changing a running
+ * context, reserve our current context
+ */
+ new_ctx = curr_ctx;
+ } else {
+ /* create a new context and reserve it */
+ new_ctx = ieee80211_new_chanctx(local, chandef, mode);
+ if (IS_ERR(new_ctx)) {
+ ret = PTR_ERR(new_ctx);
+ goto out;
+ }
}
}
@@ -770,22 +805,30 @@
sdata->vif.bss_conf.chandef = sdata->reserved_chandef;
- /* unref our reservation before assigning */
+ /* unref our reservation */
ctx->refcount--;
sdata->reserved_chanctx = NULL;
- ret = ieee80211_assign_vif_chanctx(sdata, ctx);
- if (old_ctx->refcount == 0)
- ieee80211_free_chanctx(local, old_ctx);
- if (ret) {
- /* if assign fails refcount stays the same */
- if (ctx->refcount == 0)
- ieee80211_free_chanctx(local, ctx);
- goto out;
- }
+ if (old_ctx == ctx) {
+ /* This is our own context, just change it */
+ ret = __ieee80211_vif_change_channel(sdata, old_ctx,
+ &tmp_changed);
+ if (ret)
+ goto out;
+ } else {
+ ret = ieee80211_assign_vif_chanctx(sdata, ctx);
+ if (old_ctx->refcount == 0)
+ ieee80211_free_chanctx(local, old_ctx);
+ if (ret) {
+ /* if assign fails refcount stays the same */
+ if (ctx->refcount == 0)
+ ieee80211_free_chanctx(local, ctx);
+ goto out;
+ }
- if (sdata->vif.type == NL80211_IFTYPE_AP)
- __ieee80211_vif_copy_chanctx_to_vlans(sdata, false);
+ if (sdata->vif.type == NL80211_IFTYPE_AP)
+ __ieee80211_vif_copy_chanctx_to_vlans(sdata, false);
+ }
*changed = tmp_changed;