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mac80211: introduce channel context skeleton code 

Channel context are the foundation for multi-channel
operation. They are are immutable and are re-created
(or re-used if other interfaces are bound to a certain
channel and a compatible channel type) on channel
switching.

This is an initial implementation and more features
will come in separate patches.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
[some changes including RCU protection]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Michal Kazior 2012-06-26 14:37:16 +02:00 committed by Johannes Berg
parent ddffeb8c4d
commit d01a1e6586
4 changed files with 221 additions and 0 deletions
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36
include/net/mac80211.h
View File

@ -143,6 +143,32 @@ struct ieee80211_low_level_stats {
unsigned int dot11RTSSuccessCount;
};
/**
* enum ieee80211_chanctx_change - change flag for channel context
* @IEEE80211_CHANCTX_CHANGE_CHANNEL_TYPE: The channel type was changed
*/
enum ieee80211_chanctx_change {
IEEE80211_CHANCTX_CHANGE_CHANNEL_TYPE = BIT(0),
};
/**
* struct ieee80211_chanctx_conf - channel context that vifs may be tuned to
*
* This is the driver-visible part. The ieee80211_chanctx
* that contains it is visible in mac80211 only.
*
* @channel: the channel to tune to
* @channel_type: the channel (HT) type
* @drv_priv: data area for driver use, will always be aligned to
* sizeof(void *), size is determined in hw information.
*/
struct ieee80211_chanctx_conf {
struct ieee80211_channel *channel;
enum nl80211_channel_type channel_type;
u8 drv_priv[0] __attribute__((__aligned__(sizeof(void *))));
};
/**
* enum ieee80211_bss_change - BSS change notification flags
*
@ -931,6 +957,11 @@ enum ieee80211_vif_flags {
* at runtime, mac80211 will never touch this field
* @hw_queue: hardware queue for each AC
* @cab_queue: content-after-beacon (DTIM beacon really) queue, AP mode only
* @chanctx_conf: The channel context this interface is assigned to, or %NULL
* when it is not assigned. This pointer is RCU-protected due to the TX
* path needing to access it; even though the netdev carrier will always
* be off when it is %NULL there can still be races and packets could be
* processed after it switches back to %NULL.
* @drv_priv: data area for driver use, will always be aligned to
* sizeof(void *).
*/
@ -943,6 +974,8 @@ struct ieee80211_vif {
u8 cab_queue;
u8 hw_queue[IEEE80211_NUM_ACS];
struct ieee80211_chanctx_conf __rcu *chanctx_conf;
u32 driver_flags;
/* must be last */
@ -1325,6 +1358,8 @@ enum ieee80211_hw_flags {
* within &struct ieee80211_vif.
* @sta_data_size: size (in bytes) of the drv_priv data area
* within &struct ieee80211_sta.
* @chanctx_data_size: size (in bytes) of the drv_priv data area
* within &struct ieee80211_chanctx_conf.
*
* @max_rates: maximum number of alternate rate retry stages the hw
* can handle.
@ -1369,6 +1404,7 @@ struct ieee80211_hw {
int channel_change_time;
int vif_data_size;
int sta_data_size;
int chanctx_data_size;
int napi_weight;
u16 queues;
u16 max_listen_interval;

147
net/mac80211/chan.c
View File

@ -168,3 +168,150 @@ bool ieee80211_set_channel_type(struct ieee80211_local *local,
return true;
}
static struct ieee80211_chanctx *
ieee80211_find_chanctx(struct ieee80211_local *local,
struct ieee80211_channel *channel,
enum nl80211_channel_type channel_type,
enum ieee80211_chanctx_mode mode)
{
struct ieee80211_chanctx *ctx;
lockdep_assert_held(&local->chanctx_mtx);
if (mode == IEEE80211_CHANCTX_EXCLUSIVE)
return NULL;
if (WARN_ON(!channel))
return NULL;
list_for_each_entry(ctx, &local->chanctx_list, list) {
if (ctx->mode == IEEE80211_CHANCTX_EXCLUSIVE)
continue;
if (ctx->conf.channel != channel)
continue;
if (ctx->conf.channel_type != channel_type)
continue;
return ctx;
}
return NULL;
}
static struct ieee80211_chanctx *
ieee80211_new_chanctx(struct ieee80211_local *local,
struct ieee80211_channel *channel,
enum nl80211_channel_type channel_type,
enum ieee80211_chanctx_mode mode)
{
struct ieee80211_chanctx *ctx;
lockdep_assert_held(&local->chanctx_mtx);
ctx = kzalloc(sizeof(*ctx) + local->hw.chanctx_data_size, GFP_KERNEL);
if (!ctx)
return ERR_PTR(-ENOMEM);
ctx->conf.channel = channel;
ctx->conf.channel_type = channel_type;
ctx->mode = mode;
list_add(&ctx->list, &local->chanctx_list);
return ctx;
}
static void ieee80211_free_chanctx(struct ieee80211_local *local,
struct ieee80211_chanctx *ctx)
{
lockdep_assert_held(&local->chanctx_mtx);
WARN_ON_ONCE(ctx->refcount != 0);
list_del(&ctx->list);
kfree_rcu(ctx, rcu_head);
}
static int ieee80211_assign_vif_chanctx(struct ieee80211_sub_if_data *sdata,
struct ieee80211_chanctx *ctx)
{
struct ieee80211_local *local __maybe_unused = sdata->local;
lockdep_assert_held(&local->chanctx_mtx);
rcu_assign_pointer(sdata->vif.chanctx_conf, &ctx->conf);
ctx->refcount++;
return 0;
}
static void ieee80211_unassign_vif_chanctx(struct ieee80211_sub_if_data *sdata,
struct ieee80211_chanctx *ctx)
{
struct ieee80211_local *local __maybe_unused = sdata->local;
lockdep_assert_held(&local->chanctx_mtx);
ctx->refcount--;
rcu_assign_pointer(sdata->vif.chanctx_conf, NULL);
}
static void __ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_local *local = sdata->local;
struct ieee80211_chanctx_conf *conf;
struct ieee80211_chanctx *ctx;
lockdep_assert_held(&local->chanctx_mtx);
conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
lockdep_is_held(&local->chanctx_mtx));
if (!conf)
return;
ctx = container_of(conf, struct ieee80211_chanctx, conf);
ieee80211_unassign_vif_chanctx(sdata, ctx);
if (ctx->refcount == 0)
ieee80211_free_chanctx(local, ctx);
}
int ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
struct ieee80211_channel *channel,
enum nl80211_channel_type channel_type,
enum ieee80211_chanctx_mode mode)
{
struct ieee80211_local *local = sdata->local;
struct ieee80211_chanctx *ctx;
int ret;
mutex_lock(&local->chanctx_mtx);
__ieee80211_vif_release_channel(sdata);
ctx = ieee80211_find_chanctx(local, channel, channel_type, mode);
if (!ctx)
ctx = ieee80211_new_chanctx(local, channel, channel_type, mode);
if (IS_ERR(ctx)) {
ret = PTR_ERR(ctx);
goto out;
}
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;
}
out:
mutex_unlock(&local->chanctx_mtx);
return ret;
}
void ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
{
mutex_lock(&sdata->local->chanctx_mtx);
__ieee80211_vif_release_channel(sdata);
mutex_unlock(&sdata->local->chanctx_mtx);
}

35
net/mac80211/ieee80211_i.h
View File

@ -658,6 +658,30 @@ enum ieee80211_sdata_state_bits {
SDATA_STATE_OFFCHANNEL,
};
/**
* enum ieee80211_chanctx_mode - channel context configuration mode
*
* @IEEE80211_CHANCTX_SHARED: channel context may be used by
* multiple interfaces
* @IEEE80211_CHANCTX_EXCLUSIVE: channel context can be used
* only by a single interface. This can be used for example for
* non-fixed channel IBSS.
*/
enum ieee80211_chanctx_mode {
IEEE80211_CHANCTX_SHARED,
IEEE80211_CHANCTX_EXCLUSIVE
};
struct ieee80211_chanctx {
struct list_head list;
struct rcu_head rcu_head;
enum ieee80211_chanctx_mode mode;
int refcount;
struct ieee80211_chanctx_conf conf;
};
struct ieee80211_sub_if_data {
struct list_head list;
@ -987,6 +1011,10 @@ struct ieee80211_local {
struct ieee80211_channel *tmp_channel;
enum nl80211_channel_type tmp_channel_type;
/* channel contexts */
struct list_head chanctx_list;
struct mutex chanctx_mtx;
/* SNMP counters */
/* dot11CountersTable */
u32 dot11TransmittedFragmentCount;
@ -1510,6 +1538,13 @@ bool ieee80211_set_channel_type(struct ieee80211_local *local,
enum nl80211_channel_type
ieee80211_ht_oper_to_channel_type(struct ieee80211_ht_operation *ht_oper);
int __must_check
ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
struct ieee80211_channel *channel,
enum nl80211_channel_type channel_type,
enum ieee80211_chanctx_mode mode);
void ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata);
#ifdef CONFIG_MAC80211_NOINLINE
#define debug_noinline noinline
#else

3
net/mac80211/main.c
View File

@ -626,6 +626,9 @@ struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
spin_lock_init(&local->filter_lock);
spin_lock_init(&local->queue_stop_reason_lock);
INIT_LIST_HEAD(&local->chanctx_list);
mutex_init(&local->chanctx_mtx);
/*
* The rx_skb_queue is only accessed from tasklets,
* but other SKB queues are used from within IRQ