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).
We first check if an existing compatible context exists and if it
does, we reserve it. If there is no compatible context we create a
new one and reserve it.
Additionally, split ieee80211_vif_copy_chanctx_to_vlans() so we can
call it while already holding the chanctx mutex.
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;
In v3:
* removed stray empty line;
* reworded the commit message;
* added reserved_chandef;
* added comment about reserved_chanctx and reserved_chandef protection;
* wake the queues if ieee80211_assign_vif_chanctx() fails;
In v4:
* add chanctx mode parameter to ieee80211_vif_reserve_chanctx();
* compare the vif's previous BSS width with the reserved new width
instead of comparing it to the chanctx's combined width;
In v5:
* removed a comment that was being removed, mistakenly, on the next
patch;
In v7:
* renamed local_changed variable to tmp_changed to avoid confusion;
* call ieee80211_recalc_chanctx_min_def() in
ieee80211_vif_use_reserved_chanctx();
* use new combined ieee80211_assign_vif_chanctx() when using
reserved channel;
* don't stop queues before switching context;
* call ieee80211_vif_copy_chanctx_to_vlans() in use_reserved();
In v8:
* don't set sdata->vif.bss_conf.chandef twice;
* split ieee80211_vif_copy_chanctx_to_vlans();
* don't call the recalc functions twice;
In v9:
* remove the same-context switch in use reserved() since that
should be in the next patch;
* move the local->mtx lockdep check from
ieee80211_vif_copy_chanctx_to_vlans() to the inner function;
---
net/mac80211/chan.c | 196 +++++++++++++++++++++++++++++++++++++--------
net/mac80211/ieee80211_i.h | 13 +++
2 files changed, 175 insertions(+), 34 deletions(-)
diff --git a/net/mac80211/chan.c b/net/mac80211/chan.c
index 5fa12f1..b1b92c1 100644
--- a/net/mac80211/chan.c
+++ b/net/mac80211/chan.c
@@ -420,6 +420,9 @@ 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_assign_vif_chanctx(sdata, NULL);
if (ctx->refcount == 0)
ieee80211_free_chanctx(local, ctx);
@@ -612,6 +615,165 @@ int ieee80211_vif_change_channel(struct ieee80211_sub_if_data *sdata,
return ret;
}
+static 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;
+
+ if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_AP))
+ return;
+
+ lockdep_assert_held(&local->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);
+}
+
+void ieee80211_vif_copy_chanctx_to_vlans(struct ieee80211_sub_if_data *sdata,
+ bool clear)
+{
+ struct ieee80211_local *local = sdata->local;
+
+ mutex_lock(&local->chanctx_mtx);
+
+ __ieee80211_vif_copy_chanctx_to_vlans(sdata, clear);
+
+ mutex_unlock(&local->chanctx_mtx);
+}
+
+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,
+ enum ieee80211_chanctx_mode mode)
+{
+ 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, 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;
+ }
+ }
+
+ new_ctx->refcount++;
+ sdata->reserved_chanctx = new_ctx;
+ sdata->reserved_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;
+ u32 tmp_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);
+
+ if (sdata->vif.bss_conf.chandef.width != sdata->reserved_chandef.width)
+ tmp_changed |= BSS_CHANGED_BANDWIDTH;
+
+ sdata->vif.bss_conf.chandef = sdata->reserved_chandef;
+
+ /* unref our reservation before assigning */
+ 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;
+ }
+
+ __ieee80211_vif_copy_chanctx_to_vlans(sdata, false);
+
+ *changed = tmp_changed;
+
+ ieee80211_recalc_chanctx_chantype(local, ctx);
+ ieee80211_recalc_smps_chanctx(local, ctx);
+ ieee80211_recalc_radar_chanctx(local, ctx);
+ ieee80211_recalc_chanctx_min_def(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)
@@ -691,40 +853,6 @@ 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;
-
- lockdep_assert_held(&local->mtx);
-
- 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 2f662ca..6949099 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -756,6 +756,10 @@ struct ieee80211_sub_if_data {
bool csa_radar_required;
struct cfg80211_chan_def csa_chandef;
+ /* context reservation -- protected with chanctx_mtx */
+ struct ieee80211_chanctx *reserved_chanctx;
+ struct cfg80211_chan_def reserved_chandef;
+
/* used to reconfigure hardware SM PS */
struct work_struct recalc_smps;
@@ -1776,6 +1780,15 @@ 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,
+ enum ieee80211_chanctx_mode mode);
+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);
--
1.9.0
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