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mac80211: proper IBSS locking
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IBSS has never had locking, instead relying on some
memory barriers etc. That's hard to get right, and
I think we had it wrong too until the previous patch.
Since this is not performance sensitive, it doesn't
make sense to have the maintenance overhead of that,
so add proper locking.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
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Johannes Berg authored and John W. Linville committed Jul 21, 2010
1 parent bc05d19 commit 7a17a33
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Showing 2 changed files with 54 additions and 50 deletions.
97 changes: 52 additions & 45 deletions net/mac80211/ibss.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,8 @@ static void ieee80211_rx_mgmt_auth_ibss(struct ieee80211_sub_if_data *sdata,
{
u16 auth_alg, auth_transaction, status_code;

lockdep_assert_held(&sdata->u.ibss.mtx);

if (len < 24 + 6)
return;

Expand Down Expand Up @@ -78,6 +80,8 @@ static void __ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
u32 bss_change;
u8 supp_rates[IEEE80211_MAX_SUPP_RATES];

lockdep_assert_held(&ifibss->mtx);

/* Reset own TSF to allow time synchronization work. */
drv_reset_tsf(local);

Expand Down Expand Up @@ -205,6 +209,8 @@ static void ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
int i, j;
u16 beacon_int = cbss->beacon_interval;

lockdep_assert_held(&sdata->u.ibss.mtx);

if (beacon_int < 10)
beacon_int = 10;

Expand Down Expand Up @@ -449,6 +455,8 @@ static int ieee80211_sta_active_ibss(struct ieee80211_sub_if_data *sdata)
int active = 0;
struct sta_info *sta;

lockdep_assert_held(&sdata->u.ibss.mtx);

rcu_read_lock();

list_for_each_entry_rcu(sta, &local->sta_list, list) {
Expand All @@ -473,6 +481,8 @@ static void ieee80211_sta_merge_ibss(struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;

lockdep_assert_held(&ifibss->mtx);

mod_timer(&ifibss->timer,
round_jiffies(jiffies + IEEE80211_IBSS_MERGE_INTERVAL));

Expand Down Expand Up @@ -505,6 +515,8 @@ static void ieee80211_sta_create_ibss(struct ieee80211_sub_if_data *sdata)
u16 capability;
int i;

lockdep_assert_held(&ifibss->mtx);

if (ifibss->fixed_bssid) {
memcpy(bssid, ifibss->bssid, ETH_ALEN);
} else {
Expand Down Expand Up @@ -549,6 +561,8 @@ static void ieee80211_sta_find_ibss(struct ieee80211_sub_if_data *sdata)
int active_ibss;
u16 capability;

lockdep_assert_held(&ifibss->mtx);

active_ibss = ieee80211_sta_active_ibss(sdata);
#ifdef CONFIG_MAC80211_IBSS_DEBUG
printk(KERN_DEBUG "%s: sta_find_ibss (active_ibss=%d)\n",
Expand Down Expand Up @@ -637,6 +651,8 @@ static void ieee80211_rx_mgmt_probe_req(struct ieee80211_sub_if_data *sdata,
struct ieee80211_mgmt *resp;
u8 *pos, *end;

lockdep_assert_held(&ifibss->mtx);

if (ifibss->state != IEEE80211_IBSS_MLME_JOINED ||
len < 24 + 2 || !ifibss->presp)
return;
Expand Down Expand Up @@ -740,6 +756,8 @@ void ieee80211_ibss_rx_queued_mgmt(struct ieee80211_sub_if_data *sdata,
mgmt = (struct ieee80211_mgmt *) skb->data;
fc = le16_to_cpu(mgmt->frame_control);

mutex_lock(&sdata->u.ibss.mtx);

switch (fc & IEEE80211_FCTL_STYPE) {
case IEEE80211_STYPE_PROBE_REQ:
ieee80211_rx_mgmt_probe_req(sdata, mgmt, skb->len);
Expand All @@ -756,14 +774,23 @@ void ieee80211_ibss_rx_queued_mgmt(struct ieee80211_sub_if_data *sdata,
ieee80211_rx_mgmt_auth_ibss(sdata, mgmt, skb->len);
break;
}

mutex_unlock(&sdata->u.ibss.mtx);
}

void ieee80211_ibss_work(struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;

if (!test_and_clear_bit(IEEE80211_IBSS_REQ_RUN, &ifibss->request))
return;
mutex_lock(&ifibss->mtx);

/*
* Work could be scheduled after scan or similar
* when we aren't even joined (or trying) with a
* network.
*/
if (!ifibss->ssid_len)
goto out;

switch (ifibss->state) {
case IEEE80211_IBSS_MLME_SEARCH:
Expand All @@ -776,15 +803,9 @@ void ieee80211_ibss_work(struct ieee80211_sub_if_data *sdata)
WARN_ON(1);
break;
}
}

static void ieee80211_queue_ibss_work(struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
struct ieee80211_local *local = sdata->local;

set_bit(IEEE80211_IBSS_REQ_RUN, &ifibss->request);
ieee80211_queue_work(&local->hw, &sdata->work);
out:
mutex_unlock(&ifibss->mtx);
}

static void ieee80211_ibss_timer(unsigned long data)
Expand All @@ -799,7 +820,7 @@ static void ieee80211_ibss_timer(unsigned long data)
return;
}

ieee80211_queue_ibss_work(sdata);
ieee80211_queue_work(&local->hw, &sdata->work);
}

#ifdef CONFIG_PM
Expand Down Expand Up @@ -828,6 +849,7 @@ void ieee80211_ibss_setup_sdata(struct ieee80211_sub_if_data *sdata)

setup_timer(&ifibss->timer, ieee80211_ibss_timer,
(unsigned long) sdata);
mutex_init(&ifibss->mtx);
}

/* scan finished notification */
Expand All @@ -841,10 +863,8 @@ void ieee80211_ibss_notify_scan_completed(struct ieee80211_local *local)
continue;
if (sdata->vif.type != NL80211_IFTYPE_ADHOC)
continue;
if (!sdata->u.ibss.ssid_len)
continue;
sdata->u.ibss.last_scan_completed = jiffies;
ieee80211_queue_ibss_work(sdata);
ieee80211_queue_work(&local->hw, &sdata->work);
}
mutex_unlock(&local->iflist_mtx);
}
Expand All @@ -854,6 +874,17 @@ int ieee80211_ibss_join(struct ieee80211_sub_if_data *sdata,
{
struct sk_buff *skb;

skb = dev_alloc_skb(sdata->local->hw.extra_tx_headroom +
36 /* bitrates */ +
34 /* SSID */ +
3 /* DS params */ +
4 /* IBSS params */ +
params->ie_len);
if (!skb)
return -ENOMEM;

mutex_lock(&sdata->u.ibss.mtx);

if (params->bssid) {
memcpy(sdata->u.ibss.bssid, params->bssid, ETH_ALEN);
sdata->u.ibss.fixed_bssid = true;
Expand Down Expand Up @@ -882,35 +913,19 @@ int ieee80211_ibss_join(struct ieee80211_sub_if_data *sdata,
sdata->u.ibss.ie_len = params->ie_len;
}

skb = dev_alloc_skb(sdata->local->hw.extra_tx_headroom +
36 /* bitrates */ +
34 /* SSID */ +
3 /* DS params */ +
4 /* IBSS params */ +
params->ie_len);
if (!skb)
return -ENOMEM;

sdata->u.ibss.skb = skb;
sdata->u.ibss.state = IEEE80211_IBSS_MLME_SEARCH;
sdata->u.ibss.ibss_join_req = jiffies;

memcpy(sdata->u.ibss.ssid, params->ssid, IEEE80211_MAX_SSID_LEN);

/*
* The ssid_len setting below is used to see whether
* we are active, and we need all other settings
* before that may get visible.
*/
mb();

sdata->u.ibss.ssid_len = params->ssid_len;

ieee80211_recalc_idle(sdata->local);

set_bit(IEEE80211_IBSS_REQ_RUN, &sdata->u.ibss.request);
ieee80211_queue_work(&sdata->local->hw, &sdata->work);

mutex_unlock(&sdata->u.ibss.mtx);

return 0;
}

Expand All @@ -921,7 +936,9 @@ int ieee80211_ibss_leave(struct ieee80211_sub_if_data *sdata)
struct ieee80211_local *local = sdata->local;
struct cfg80211_bss *cbss;
u16 capability;
int active_ibss = 0;
int active_ibss;

mutex_lock(&sdata->u.ibss.mtx);

active_ibss = ieee80211_sta_active_ibss(sdata);

Expand Down Expand Up @@ -959,19 +976,9 @@ int ieee80211_ibss_leave(struct ieee80211_sub_if_data *sdata)
memset(sdata->u.ibss.bssid, 0, ETH_ALEN);
sdata->u.ibss.ssid_len = 0;

/*
* ssid_len indicates active or not, so needs to be visible to
* everybody, especially ieee80211_ibss_notify_scan_completed,
* so it won't restart the timer after we remove it here.
*/
mb();

del_timer_sync(&sdata->u.ibss.timer);
clear_bit(IEEE80211_IBSS_REQ_RUN, &sdata->u.ibss.request);
/*
* Since the REQ_RUN bit is clear, the work won't do
* anything if it runs after this.
*/

mutex_unlock(&sdata->u.ibss.mtx);

ieee80211_recalc_idle(sdata->local);

Expand Down
7 changes: 2 additions & 5 deletions net/mac80211/ieee80211_i.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -377,14 +377,11 @@ struct ieee80211_if_managed {
int last_cqm_event_signal;
};

enum ieee80211_ibss_request {
IEEE80211_IBSS_REQ_RUN = 0,
};

struct ieee80211_if_ibss {
struct timer_list timer;

unsigned long request;
struct mutex mtx;

unsigned long last_scan_completed;

u32 basic_rates;
Expand Down

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