Commit 11335a55 authored by Luciano Coelho's avatar Luciano Coelho Committed by Johannes Berg
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mac80211: implement chanctx reservation 



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: default avatarLuciano Coelho <luciano.coelho@intel.com>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 77eeba97

net/mac80211/chan.c

+163 −34
Original line number Diff line number Diff line
@@ -426,6 +426,9 @@ 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);
@@ -635,6 +638,166 @@ 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;

	}



	if (sdata->vif.type == NL80211_IFTYPE_AP)

		__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)
@@ -714,40 +877,6 @@ 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,

net/mac80211/ieee80211_i.h

+13 −0
Original line number Diff line number Diff line
@@ -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;
@@ -1770,6 +1774,15 @@ int __must_check 
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,

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