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mac80211: clean up mesh sta allocation warning
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This refactoring fixes a "scheduling while atomic" warning
when allocating a mesh station entry while holding the RCU
read lock. Fix this by creating a new function
mesh_sta_info_get(), which correctly handles the locking
and returns under RCU.

Also move some unnecessarily #ifdefed mesh station init
code from sta_info_alloc() to __mesh_sta_info_alloc().

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
[change code flow to make sparse happy]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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Thomas Pedersen authored and Johannes Berg committed Jan 24, 2013
1 parent d437c86 commit 296fcba
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Showing 2 changed files with 95 additions and 68 deletions.
158 changes: 95 additions & 63 deletions net/mac80211/mesh_plink.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -55,30 +55,6 @@ static inline void mesh_plink_fsm_restart(struct sta_info *sta)
sta->plink_retries = 0;
}

/*
* Allocate mesh sta entry and insert into station table
*/
static struct sta_info *mesh_plink_alloc(struct ieee80211_sub_if_data *sdata,
u8 *hw_addr)
{
struct sta_info *sta;

if (sdata->local->num_sta >= MESH_MAX_PLINKS)
return NULL;

sta = sta_info_alloc(sdata, hw_addr, GFP_KERNEL);
if (!sta)
return NULL;

sta_info_pre_move_state(sta, IEEE80211_STA_AUTH);
sta_info_pre_move_state(sta, IEEE80211_STA_ASSOC);
sta_info_pre_move_state(sta, IEEE80211_STA_AUTHORIZED);

set_sta_flag(sta, WLAN_STA_WME);

return sta;
}

/**
* mesh_set_ht_prot_mode - set correct HT protection mode
*
Expand Down Expand Up @@ -309,52 +285,24 @@ static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
return err;
}

/**
* mesh_peer_init - initialize new mesh peer and return resulting sta_info
*
* @sdata: local meshif
* @addr: peer's address
* @elems: IEs from beacon or mesh peering frame
*
* call under RCU
*/
static struct sta_info *mesh_peer_init(struct ieee80211_sub_if_data *sdata,
u8 *addr,
struct ieee802_11_elems *elems)
static void mesh_sta_info_init(struct ieee80211_sub_if_data *sdata,
struct sta_info *sta,
struct ieee802_11_elems *elems, bool insert)
{
struct ieee80211_local *local = sdata->local;
enum ieee80211_band band = ieee80211_get_sdata_band(sdata);
struct ieee80211_supported_band *sband;
u32 rates, basic_rates = 0;
struct sta_info *sta;
bool insert = false;

sband = local->hw.wiphy->bands[band];
rates = ieee80211_sta_get_rates(local, elems, band, &basic_rates);

sta = sta_info_get(sdata, addr);
if (!sta) {
/* Userspace handles peer allocation when security is enabled */
if (sdata->u.mesh.security & IEEE80211_MESH_SEC_AUTHED) {
cfg80211_notify_new_peer_candidate(sdata->dev, addr,
elems->ie_start,
elems->total_len,
GFP_ATOMIC);
return NULL;
}

sta = mesh_plink_alloc(sdata, addr);
if (!sta)
return NULL;
insert = true;
}

spin_lock_bh(&sta->lock);
sta->last_rx = jiffies;
if (sta->plink_state == NL80211_PLINK_ESTAB) {
spin_unlock_bh(&sta->lock);
return sta;
}

/* rates and capabilities don't change during peering */
if (sta->plink_state == NL80211_PLINK_ESTAB)
goto out;

sta->sta.supp_rates[band] = rates;
if (elems->ht_cap_elem &&
Expand All @@ -379,22 +327,104 @@ static struct sta_info *mesh_peer_init(struct ieee80211_sub_if_data *sdata,

if (insert)
rate_control_rate_init(sta);
out:
spin_unlock_bh(&sta->lock);
}

static struct sta_info *
__mesh_sta_info_alloc(struct ieee80211_sub_if_data *sdata, u8 *hw_addr)
{
struct sta_info *sta;

if (insert && sta_info_insert(sta))
if (sdata->local->num_sta >= MESH_MAX_PLINKS)
return NULL;

sta = sta_info_alloc(sdata, hw_addr, GFP_KERNEL);
if (!sta)
return NULL;

sta->plink_state = NL80211_PLINK_LISTEN;
init_timer(&sta->plink_timer);

sta_info_pre_move_state(sta, IEEE80211_STA_AUTH);
sta_info_pre_move_state(sta, IEEE80211_STA_ASSOC);
sta_info_pre_move_state(sta, IEEE80211_STA_AUTHORIZED);

set_sta_flag(sta, WLAN_STA_WME);

return sta;
}

static struct sta_info *
mesh_sta_info_alloc(struct ieee80211_sub_if_data *sdata, u8 *addr,
struct ieee802_11_elems *elems)
{
struct sta_info *sta = NULL;

/* Userspace handles peer allocation when security is enabled */
if (sdata->u.mesh.security & IEEE80211_MESH_SEC_AUTHED)
cfg80211_notify_new_peer_candidate(sdata->dev, addr,
elems->ie_start,
elems->total_len,
GFP_KERNEL);
else
sta = __mesh_sta_info_alloc(sdata, addr);

return sta;
}

/*
* mesh_sta_info_get - return mesh sta info entry for @addr.
*
* @sdata: local meshif
* @addr: peer's address
* @elems: IEs from beacon or mesh peering frame.
*
* Return existing or newly allocated sta_info under RCU read lock.
* (re)initialize with given IEs.
*/
static struct sta_info *
mesh_sta_info_get(struct ieee80211_sub_if_data *sdata,
u8 *addr, struct ieee802_11_elems *elems) __acquires(RCU)
{
struct sta_info *sta = NULL;

rcu_read_lock();
sta = sta_info_get(sdata, addr);
if (sta) {
mesh_sta_info_init(sdata, sta, elems, false);
} else {
rcu_read_unlock();
/* can't run atomic */
sta = mesh_sta_info_alloc(sdata, addr, elems);
if (!sta) {
rcu_read_lock();
return NULL;
}

if (sta_info_insert_rcu(sta))
return NULL;
}

return sta;
}

/*
* mesh_neighbour_update - update or initialize new mesh neighbor.
*
* @sdata: local meshif
* @addr: peer's address
* @elems: IEs from beacon or mesh peering frame
*
* Initiates peering if appropriate.
*/
void mesh_neighbour_update(struct ieee80211_sub_if_data *sdata,
u8 *hw_addr,
struct ieee802_11_elems *elems)
{
struct sta_info *sta;

rcu_read_lock();
sta = mesh_peer_init(sdata, hw_addr, elems);
sta = mesh_sta_info_get(sdata, hw_addr, elems);
if (!sta)
goto out;

Expand Down Expand Up @@ -632,6 +662,7 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m
(ftype == WLAN_SP_MESH_PEERING_CLOSE && ie_len == 8))
memcpy(&llid, PLINK_GET_PLID(elems.peering), 2);

/* WARNING: Only for sta pointer, is dropped & re-acquired */
rcu_read_lock();

sta = sta_info_get(sdata, mgmt->sa);
Expand Down Expand Up @@ -735,8 +766,9 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m
}

if (event == OPN_ACPT) {
rcu_read_unlock();
/* allocate sta entry if necessary and update info */
sta = mesh_peer_init(sdata, mgmt->sa, &elems);
sta = mesh_sta_info_get(sdata, mgmt->sa, &elems);
if (!sta) {
mpl_dbg(sdata, "Mesh plink: failed to init peer!\n");
rcu_read_unlock();
Expand Down
5 changes: 0 additions & 5 deletions net/mac80211/sta_info.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -380,11 +380,6 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,

sta_dbg(sdata, "Allocated STA %pM\n", sta->sta.addr);

#ifdef CONFIG_MAC80211_MESH
sta->plink_state = NL80211_PLINK_LISTEN;
init_timer(&sta->plink_timer);
#endif

return sta;
}

Expand Down

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