Return-path: Received: from mga02.intel.com ([134.134.136.20]:35305 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755362AbaCRPGr (ORCPT ); Tue, 18 Mar 2014 11:06:47 -0400 From: Luciano Coelho To: linux-wireless@vger.kernel.org Cc: johannes@sipsolutions.net, michal.kazior@tieto.com, sw@simonwunderlich.de, andrei.otcheretianski@intel.com Subject: [PATCH v10 3/4] mac80211: implement chanctx reservation Date: Tue, 18 Mar 2014 17:03:05 +0200 Message-Id: <1395154986-13810-4-git-send-email-luciano.coelho@intel.com> (sfid-20140318_160651_878419_21B5BDE1) In-Reply-To: <1395154986-13810-1-git-send-email-luciano.coelho@intel.com> References: <1395154986-13810-1-git-send-email-luciano.coelho@intel.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: 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 --- 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; In v10: * only call __ieee80211_vif_copy_chanctx_to_vlans() if the vif type is AP. Signed-off-by: Luciano Coelho --- net/mac80211/chan.c | 197 +++++++++++++++++++++++++++++++++++++-------- net/mac80211/ieee80211_i.h | 13 +++ 2 files changed, 176 insertions(+), 34 deletions(-) diff --git a/net/mac80211/chan.c b/net/mac80211/chan.c index 5fa12f1..f7e581b 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 +615,166 @@ 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) @@ -691,40 +854,6 @@ 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