From: Johannes Berg <johannes.berg@xxxxxxxxx>
The last fixes re-added the RCU synchronize penalty
on roaming to fix the races. Split up sta_info_flush()
now to get rid of that again, and let managed mode
(and only it) delay the actual destruction.
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
---
net/mac80211/iface.c | 15 ++++++++++-----
net/mac80211/mlme.c | 2 +-
net/mac80211/sta_info.c | 27 +++++++++++++++++----------
net/mac80211/sta_info.h | 21 ++++++++++++++++++++-
4 files changed, 48 insertions(+), 17 deletions(-)
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 9dacc3a..ab47df0 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -784,8 +784,10 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
* This is relevant only in WDS mode, in all other modes we've
* already removed all stations when disconnecting or similar,
* so warn otherwise.
+ *
+ * We call sta_info_flush_cleanup() later, to combine RCU waits.
*/
- flushed = sta_info_flush(sdata);
+ flushed = sta_info_flush_defer(sdata);
WARN_ON_ONCE((sdata->vif.type != NL80211_IFTYPE_WDS && flushed > 0) ||
(sdata->vif.type == NL80211_IFTYPE_WDS && flushed != 1));
@@ -870,11 +872,14 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
cancel_work_sync(&sdata->work);
/*
* When we get here, the interface is marked down.
- * Call synchronize_rcu() to wait for the RX path
- * should it be using the interface and enqueuing
- * frames at this very time on another CPU.
+ * sta_info_flush_cleanup() calls rcu_barrier to
+ * wait for the station call_rcu() calls to complete,
+ * here we require it to wait for the RX path in case
+ * it is using the interface and enqueuing frames at
+ * this very time on another CPU.
*/
- synchronize_rcu();
+ sta_info_flush_cleanup(sdata);
+
skb_queue_purge(&sdata->skb_queue);
/*
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 7cbb4cb..964c33e 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1518,7 +1518,7 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
memset(ifmgd->bssid, 0, ETH_ALEN);
/* remove AP and TDLS peers */
- sta_info_flush(sdata);
+ sta_info_flush_defer(sdata);
/* finally reset all BSS / config parameters */
changed |= ieee80211_reset_erp_info(sdata);
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 1a84a52..2f74031 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -104,6 +104,16 @@ static void cleanup_single_sta(struct sta_info *sta)
* neither mac80211 nor the driver can reference this
* sta struct any more except by still existing timers
* associated with this station that we clean up below.
+ *
+ * Note though that this still uses the sdata and even
+ * calls the driver in AP and mesh mode, so interfaces
+ * of those types mush use call sta_info_flush_cleanup()
+ * (typically via sta_info_flush()) before deconfiguring
+ * the driver.
+ *
+ * In station mode, nothing happens here so it doesn't
+ * have to (and doesn't) do that, this is intentional to
+ * speed up roaming.
*/
if (test_sta_flag(sta, WLAN_STA_PS_STA)) {
@@ -887,14 +897,8 @@ void sta_info_stop(struct ieee80211_local *local)
del_timer_sync(&local->sta_cleanup);
}
-/**
- * sta_info_flush - flush matching STA entries from the STA table
- *
- * Returns the number of removed STA entries.
- *
- * @sdata: sdata to remove all stations from
- */
-int sta_info_flush(struct ieee80211_sub_if_data *sdata)
+
+int sta_info_flush_defer(struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_local *local = sdata->local;
struct sta_info *sta, *tmp;
@@ -911,12 +915,15 @@ int sta_info_flush(struct ieee80211_sub_if_data *sdata)
}
mutex_unlock(&local->sta_mtx);
+ return ret;
+}
+
+void sta_info_flush_cleanup(struct ieee80211_sub_if_data *sdata)
+{
rcu_barrier();
ieee80211_cleanup_sdata_stas(sdata);
cancel_work_sync(&sdata->cleanup_stations_wk);
-
- return ret;
}
void ieee80211_sta_expire(struct ieee80211_sub_if_data *sdata,
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index 13698da..93e8ae7 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -548,7 +548,26 @@ void sta_info_recalc_tim(struct sta_info *sta);
void sta_info_init(struct ieee80211_local *local);
void sta_info_stop(struct ieee80211_local *local);
-int sta_info_flush(struct ieee80211_sub_if_data *sdata);
+int sta_info_flush_defer(struct ieee80211_sub_if_data *sdata);
+void sta_info_flush_cleanup(struct ieee80211_sub_if_data *sdata);
+
+/**
+ * sta_info_flush - flush matching STA entries from the STA table
+ *
+ * Returns the number of removed STA entries.
+ *
+ * @sdata: sdata to remove all stations from
+ */
+static inline int sta_info_flush(struct ieee80211_sub_if_data *sdata)
+{
+ int ret = sta_info_flush_defer(sdata);
+
+ if (ret)
+ sta_info_flush_cleanup(sdata);
+
+ return ret;
+}
+
void sta_set_rate_info_tx(struct sta_info *sta,
const struct ieee80211_tx_rate *rate,
struct rate_info *rinfo);
--
1.8.0
--
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