From: Luciano Coelho <luciano.coelho@xxxxxxxxx>
In order to support channel switch with multiple vifs and multiple
contexts, we implement a concept of channel context reservation. This
allows us to reserve a channel context to be used later.
The reservation functionality is not tied directly to channel switch
and may be used in other situations (eg. reserving a channel context
during IBSS join).
When reserving the context, the following algorithm is used:
1) try to find an existing context that matches our future chandef and
reserve it if it exists;
2) otherwise, check if we're the only vif in the current context, in
which case we can just change our current context. To prevent
other vifs from joining this context in the meantime, we mark it as
exclusive. This is an optimization to avoid using extra contexts
when not necessary and requires the driver to support changing a
context on-the-fly;
3) if we're not the only vif in the current context, create a new
context and reserve it;
Signed-off-by: Luciano Coelho <luciano.coelho@xxxxxxxxx>
---
In RFC v2:
* reformulated the patch to make channel reservation generic and
not only for channel switch, as we may find other uses for it in
the future;
* added ieee80211_vif_unreserve_chanctx();
* removed reservation of the current chanctx from this patch;
* added a stop_queue_reason for chanctx reservation;
* added a few TODOs according to Michal's comments to be handled in
future patch series;
* set sdata->csa_chandef to the received chandef in all cases (it
was only happening in the alone-in-the-vif case;
---
net/mac80211/chan.c | 139 +++++++++++++++++++++++++++++++++++++++++++++
net/mac80211/ieee80211_i.h | 11 ++++
2 files changed, 150 insertions(+)
diff --git a/net/mac80211/chan.c b/net/mac80211/chan.c
index a27c6ec..bd42d17 100644
--- a/net/mac80211/chan.c
+++ b/net/mac80211/chan.c
@@ -419,6 +419,9 @@ static void __ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
ctx = container_of(conf, struct ieee80211_chanctx, conf);
+ if (sdata->reserved_chanctx)
+ ieee80211_vif_unreserve_chanctx(sdata);
+
ieee80211_unassign_vif_chanctx(sdata, ctx);
if (ctx->refcount == 0)
ieee80211_free_chanctx(local, ctx);
@@ -611,6 +614,142 @@ int ieee80211_vif_change_channel(struct ieee80211_sub_if_data *sdata,
return ret;
}
+int ieee80211_vif_unreserve_chanctx(struct ieee80211_sub_if_data *sdata)
+{
+
+ lockdep_assert_held(&sdata->local->chanctx_mtx);
+
+ if (WARN_ON(!sdata->reserved_chanctx))
+ return -EINVAL;
+
+ if (--sdata->reserved_chanctx->refcount == 0)
+ ieee80211_free_chanctx(sdata->local, sdata->reserved_chanctx);
+
+ sdata->reserved_chanctx = NULL;
+
+ return 0;
+}
+
+int ieee80211_vif_reserve_chanctx(struct ieee80211_sub_if_data *sdata,
+ const struct cfg80211_chan_def *chandef)
+{
+ struct ieee80211_local *local = sdata->local;
+ struct ieee80211_chanctx_conf *conf;
+ struct ieee80211_chanctx *new_ctx, *curr_ctx;
+ int ret = 0;
+
+ mutex_lock(&local->chanctx_mtx);
+
+ conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
+ lockdep_is_held(&local->chanctx_mtx));
+ if (!conf) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ curr_ctx = container_of(conf, struct ieee80211_chanctx, conf);
+
+ /* try to find another context with the chandef we want */
+ new_ctx = ieee80211_find_chanctx(local, chandef,
+ IEEE80211_CHANCTX_SHARED);
+ if (!new_ctx) {
+ /* create a new context */
+ new_ctx = ieee80211_new_chanctx(local, chandef,
+ IEEE80211_CHANCTX_SHARED);
+ if (IS_ERR(new_ctx)) {
+ ret = PTR_ERR(new_ctx);
+ goto out;
+ }
+ }
+
+ /* reserve the new or existing context */
+ sdata->reserved_chanctx = new_ctx;
+ new_ctx->refcount++;
+
+ sdata->csa_chandef = *chandef;
+out:
+ mutex_unlock(&local->chanctx_mtx);
+ return ret;
+}
+
+int ieee80211_vif_use_reserved_context(struct ieee80211_sub_if_data *sdata,
+ u32 *changed)
+{
+ struct ieee80211_local *local = sdata->local;
+ struct ieee80211_chanctx *ctx;
+ struct ieee80211_chanctx *old_ctx;
+ struct ieee80211_chanctx_conf *conf;
+ int ret, local_changed = *changed;
+
+ /* TODO: need to recheck if the chandef is usable etc.? */
+
+ lockdep_assert_held(&local->mtx);
+
+ mutex_lock(&local->chanctx_mtx);
+
+ ctx = sdata->reserved_chanctx;
+ if (WARN_ON(!ctx)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
+ lockdep_is_held(&local->chanctx_mtx));
+ if (!conf) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ old_ctx = container_of(conf, struct ieee80211_chanctx, conf);
+
+ ieee80211_stop_queues_by_reason(&local->hw,
+ IEEE80211_MAX_QUEUE_MAP,
+ IEEE80211_QUEUE_STOP_REASON_CHANCTX);
+
+ ieee80211_unassign_vif_chanctx(sdata, old_ctx);
+ if (old_ctx->refcount == 0)
+ ieee80211_free_chanctx(local, old_ctx);
+
+ /* TODO: we're assuming that the bandwidth of the context
+ * changes here, but in fact, it will only change if the
+ * combination of the channels used in this context change.
+ * We should set this flag according to what happens when
+ * ieee80211_recalc_chanctx_chantype() is called. Maybe the
+ * nicest thing to do would be to change that function so that
+ * it returns changed flags (which will be either 0 or
+ * BSS_CHANGED_BANDWIDTH).
+ */
+
+ if (sdata->vif.bss_conf.chandef.width != ctx->conf.def.width)
+ local_changed |= BSS_CHANGED_BANDWIDTH;
+
+ sdata->vif.bss_conf.chandef = ctx->conf.def;
+
+ /* unref our reservation before assigning */
+ ctx->refcount--;
+ sdata->reserved_chanctx = NULL;
+ ret = ieee80211_assign_vif_chanctx(sdata, ctx);
+ if (ret) {
+ /* if assign fails refcount stays the same */
+ if (ctx->refcount == 0)
+ ieee80211_free_chanctx(local, ctx);
+ goto out;
+ }
+
+ ieee80211_wake_queues_by_reason(&sdata->local->hw,
+ IEEE80211_MAX_QUEUE_MAP,
+ IEEE80211_QUEUE_STOP_REASON_CHANCTX);
+
+ *changed = local_changed;
+
+ ieee80211_recalc_chanctx_chantype(local, ctx);
+ ieee80211_recalc_smps_chanctx(local, ctx);
+ ieee80211_recalc_radar_chanctx(local, ctx);
+out:
+ mutex_unlock(&local->chanctx_mtx);
+ return ret;
+}
+
int ieee80211_vif_change_bandwidth(struct ieee80211_sub_if_data *sdata,
const struct cfg80211_chan_def *chandef,
u32 *changed)
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 8603dfb..998fbbb 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -756,6 +756,8 @@ struct ieee80211_sub_if_data {
bool csa_radar_required;
struct cfg80211_chan_def csa_chandef;
+ struct ieee80211_chanctx *reserved_chanctx;
+
/* used to reconfigure hardware SM PS */
struct work_struct recalc_smps;
@@ -899,6 +901,7 @@ enum queue_stop_reason {
IEEE80211_QUEUE_STOP_REASON_SKB_ADD,
IEEE80211_QUEUE_STOP_REASON_OFFCHANNEL,
IEEE80211_QUEUE_STOP_REASON_FLUSH,
+ IEEE80211_QUEUE_STOP_REASON_CHANCTX,
};
#ifdef CONFIG_MAC80211_LEDS
@@ -1776,6 +1779,14 @@ ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
const struct cfg80211_chan_def *chandef,
enum ieee80211_chanctx_mode mode);
int __must_check
+ieee80211_vif_reserve_chanctx(struct ieee80211_sub_if_data *sdata,
+ const struct cfg80211_chan_def *chandef);
+int __must_check
+ieee80211_vif_use_reserved_context(struct ieee80211_sub_if_data *sdata,
+ u32 *changed);
+int ieee80211_vif_unreserve_chanctx(struct ieee80211_sub_if_data *sdata);
+
+int __must_check
ieee80211_vif_change_bandwidth(struct ieee80211_sub_if_data *sdata,
const struct cfg80211_chan_def *chandef,
u32 *changed);
--
1.8.5.3
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