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mac80211: introduce plink lock for plink fields
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The mesh plink code uses sta->lock to serialize access to the
plink state fields between the peer link state machine and the
peer link timer.  Some paths (e.g. those involving
mps_qos_null_tx()) unfortunately hold this spinlock across
frame tx, which is soon to be disallowed.  Add a new spinlock
just for plink access.

Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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Bob Copeland authored and Johannes Berg committed Apr 20, 2015
1 parent 388f997 commit 48bf6be
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Showing 3 changed files with 25 additions and 18 deletions.
37 changes: 20 additions & 17 deletions net/mac80211/mesh_plink.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -72,10 +72,11 @@ static bool rssi_threshold_check(struct ieee80211_sub_if_data *sdata,
*
* @sta: mesh peer link to restart
*
* Locking: this function must be called holding sta->lock
* Locking: this function must be called holding sta->plink_lock
*/
static inline void mesh_plink_fsm_restart(struct sta_info *sta)
{
lockdep_assert_held(&sta->plink_lock);
sta->plink_state = NL80211_PLINK_LISTEN;
sta->llid = sta->plid = sta->reason = 0;
sta->plink_retries = 0;
Expand Down Expand Up @@ -213,13 +214,15 @@ static u32 mesh_set_ht_prot_mode(struct ieee80211_sub_if_data *sdata)
* All mesh paths with this peer as next hop will be flushed
* Returns beacon changed flag if the beacon content changed.
*
* Locking: the caller must hold sta->lock
* Locking: the caller must hold sta->plink_lock
*/
static u32 __mesh_plink_deactivate(struct sta_info *sta)
{
struct ieee80211_sub_if_data *sdata = sta->sdata;
u32 changed = 0;

lockdep_assert_held(&sta->plink_lock);

if (sta->plink_state == NL80211_PLINK_ESTAB)
changed = mesh_plink_dec_estab_count(sdata);
sta->plink_state = NL80211_PLINK_BLOCKED;
Expand All @@ -244,13 +247,13 @@ u32 mesh_plink_deactivate(struct sta_info *sta)
struct ieee80211_sub_if_data *sdata = sta->sdata;
u32 changed;

spin_lock_bh(&sta->lock);
spin_lock_bh(&sta->plink_lock);
changed = __mesh_plink_deactivate(sta);
sta->reason = WLAN_REASON_MESH_PEER_CANCELED;
mesh_plink_frame_tx(sdata, WLAN_SP_MESH_PEERING_CLOSE,
sta->sta.addr, sta->llid, sta->plid,
sta->reason);
spin_unlock_bh(&sta->lock);
spin_unlock_bh(&sta->plink_lock);

return changed;
}
Expand Down Expand Up @@ -387,7 +390,7 @@ static void mesh_sta_info_init(struct ieee80211_sub_if_data *sdata,
sband = local->hw.wiphy->bands[band];
rates = ieee80211_sta_get_rates(sdata, elems, band, &basic_rates);

spin_lock_bh(&sta->lock);
spin_lock_bh(&sta->plink_lock);
sta->last_rx = jiffies;

/* rates and capabilities don't change during peering */
Expand Down Expand Up @@ -419,7 +422,7 @@ static void mesh_sta_info_init(struct ieee80211_sub_if_data *sdata,
else
rate_control_rate_update(local, sband, sta, changed);
out:
spin_unlock_bh(&sta->lock);
spin_unlock_bh(&sta->plink_lock);
}

static struct sta_info *
Expand Down Expand Up @@ -552,7 +555,7 @@ static void mesh_plink_timer(unsigned long data)
if (sta->sdata->local->quiescing)
return;

spin_lock_bh(&sta->lock);
spin_lock_bh(&sta->plink_lock);

/* If a timer fires just before a state transition on another CPU,
* we may have already extended the timeout and changed state by the
Expand All @@ -563,7 +566,7 @@ static void mesh_plink_timer(unsigned long data)
mpl_dbg(sta->sdata,
"Ignoring timer for %pM in state %s (timer adjusted)",
sta->sta.addr, mplstates[sta->plink_state]);
spin_unlock_bh(&sta->lock);
spin_unlock_bh(&sta->plink_lock);
return;
}

Expand All @@ -573,7 +576,7 @@ static void mesh_plink_timer(unsigned long data)
mpl_dbg(sta->sdata,
"Ignoring timer for %pM in state %s (timer deleted)",
sta->sta.addr, mplstates[sta->plink_state]);
spin_unlock_bh(&sta->lock);
spin_unlock_bh(&sta->plink_lock);
return;
}

Expand Down Expand Up @@ -619,7 +622,7 @@ static void mesh_plink_timer(unsigned long data)
default:
break;
}
spin_unlock_bh(&sta->lock);
spin_unlock_bh(&sta->plink_lock);
if (action)
mesh_plink_frame_tx(sdata, action, sta->sta.addr,
sta->llid, sta->plid, reason);
Expand Down Expand Up @@ -674,16 +677,16 @@ u32 mesh_plink_open(struct sta_info *sta)
if (!test_sta_flag(sta, WLAN_STA_AUTH))
return 0;

spin_lock_bh(&sta->lock);
spin_lock_bh(&sta->plink_lock);
sta->llid = mesh_get_new_llid(sdata);
if (sta->plink_state != NL80211_PLINK_LISTEN &&
sta->plink_state != NL80211_PLINK_BLOCKED) {
spin_unlock_bh(&sta->lock);
spin_unlock_bh(&sta->plink_lock);
return 0;
}
sta->plink_state = NL80211_PLINK_OPN_SNT;
mesh_plink_timer_set(sta, sdata->u.mesh.mshcfg.dot11MeshRetryTimeout);
spin_unlock_bh(&sta->lock);
spin_unlock_bh(&sta->plink_lock);
mpl_dbg(sdata,
"Mesh plink: starting establishment with %pM\n",
sta->sta.addr);
Expand All @@ -700,10 +703,10 @@ u32 mesh_plink_block(struct sta_info *sta)
{
u32 changed;

spin_lock_bh(&sta->lock);
spin_lock_bh(&sta->plink_lock);
changed = __mesh_plink_deactivate(sta);
sta->plink_state = NL80211_PLINK_BLOCKED;
spin_unlock_bh(&sta->lock);
spin_unlock_bh(&sta->plink_lock);

return changed;
}
Expand Down Expand Up @@ -758,7 +761,7 @@ static u32 mesh_plink_fsm(struct ieee80211_sub_if_data *sdata,
mpl_dbg(sdata, "peer %pM in state %s got event %s\n", sta->sta.addr,
mplstates[sta->plink_state], mplevents[event]);

spin_lock_bh(&sta->lock);
spin_lock_bh(&sta->plink_lock);
switch (sta->plink_state) {
case NL80211_PLINK_LISTEN:
switch (event) {
Expand Down Expand Up @@ -872,7 +875,7 @@ static u32 mesh_plink_fsm(struct ieee80211_sub_if_data *sdata,
*/
break;
}
spin_unlock_bh(&sta->lock);
spin_unlock_bh(&sta->plink_lock);
if (action) {
mesh_plink_frame_tx(sdata, action, sta->sta.addr,
sta->llid, sta->plid, sta->reason);
Expand Down
1 change: 1 addition & 0 deletions net/mac80211/sta_info.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -295,6 +295,7 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
INIT_WORK(&sta->ampdu_mlme.work, ieee80211_ba_session_work);
mutex_init(&sta->ampdu_mlme.mtx);
#ifdef CONFIG_MAC80211_MESH
spin_lock_init(&sta->plink_lock);
if (ieee80211_vif_is_mesh(&sdata->vif) &&
!sdata->u.mesh.user_mpm)
init_timer(&sta->plink_timer);
Expand Down
5 changes: 4 additions & 1 deletion net/mac80211/sta_info.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -299,6 +299,7 @@ struct sta_ampdu_mlme {
* @tid_seq: per-TID sequence numbers for sending to this STA
* @ampdu_mlme: A-MPDU state machine state
* @timer_to_tid: identity mapping to ID timers
* @plink_lock: serialize access to plink fields
* @llid: Local link ID
* @plid: Peer link ID
* @reason: Cancel reason on PLINK_HOLDING state
Expand Down Expand Up @@ -422,16 +423,18 @@ struct sta_info {

#ifdef CONFIG_MAC80211_MESH
/*
* Mesh peer link attributes
* Mesh peer link attributes, protected by plink_lock.
* TODO: move to a sub-structure that is referenced with pointer?
*/
spinlock_t plink_lock;
u16 llid;
u16 plid;
u16 reason;
u8 plink_retries;
enum nl80211_plink_state plink_state;
u32 plink_timeout;
struct timer_list plink_timer;

s64 t_offset;
s64 t_offset_setpoint;
/* mesh power save */
Expand Down

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