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authorFelix Fietkau <nbd@openwrt.org>2013-05-03 12:01:03 +0400
committerJohannes Berg <johannes.berg@intel.com>2013-05-17 00:38:05 +0400
commitf6b3d85f7f6d66f890862d763b2ed092c5dd4322 (patch)
tree3e6ca47a09a6ee3418aa2ab14d14d3534c2b9279
parent3670946fe2e942bcb09ec9bbc587bf305f9f97da (diff)
downloadlinux-f6b3d85f7f6d66f890862d763b2ed092c5dd4322.tar.xz
mac80211: fix spurious RCU warning and update documentation
Document rx vs tx status concurrency requirements. Signed-off-by: Felix Fietkau <nbd@openwrt.org> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
-rw-r--r--include/net/mac80211.h12
-rw-r--r--net/mac80211/rate.c9
2 files changed, 16 insertions, 5 deletions
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 04c2d4670dc6..885898a40d13 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -3043,7 +3043,8 @@ void ieee80211_napi_complete(struct ieee80211_hw *hw);
* This function may not be called in IRQ context. Calls to this function
* for a single hardware must be synchronized against each other. Calls to
* this function, ieee80211_rx_ni() and ieee80211_rx_irqsafe() may not be
- * mixed for a single hardware.
+ * mixed for a single hardware. Must not run concurrently with
+ * ieee80211_tx_status() or ieee80211_tx_status_ni().
*
* In process context use instead ieee80211_rx_ni().
*
@@ -3059,7 +3060,8 @@ void ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb);
* (internally defers to a tasklet.)
*
* Calls to this function, ieee80211_rx() or ieee80211_rx_ni() may not
- * be mixed for a single hardware.
+ * be mixed for a single hardware.Must not run concurrently with
+ * ieee80211_tx_status() or ieee80211_tx_status_ni().
*
* @hw: the hardware this frame came in on
* @skb: the buffer to receive, owned by mac80211 after this call
@@ -3073,7 +3075,8 @@ void ieee80211_rx_irqsafe(struct ieee80211_hw *hw, struct sk_buff *skb);
* (internally disables bottom halves).
*
* Calls to this function, ieee80211_rx() and ieee80211_rx_irqsafe() may
- * not be mixed for a single hardware.
+ * not be mixed for a single hardware. Must not run concurrently with
+ * ieee80211_tx_status() or ieee80211_tx_status_ni().
*
* @hw: the hardware this frame came in on
* @skb: the buffer to receive, owned by mac80211 after this call
@@ -3196,7 +3199,8 @@ void ieee80211_get_tx_rates(struct ieee80211_vif *vif,
* This function may not be called in IRQ context. Calls to this function
* for a single hardware must be synchronized against each other. Calls
* to this function, ieee80211_tx_status_ni() and ieee80211_tx_status_irqsafe()
- * may not be mixed for a single hardware.
+ * may not be mixed for a single hardware. Must not run concurrently with
+ * ieee80211_rx() or ieee80211_rx_ni().
*
* @hw: the hardware the frame was transmitted by
* @skb: the frame that was transmitted, owned by mac80211 after this call
diff --git a/net/mac80211/rate.c b/net/mac80211/rate.c
index 0d51877efdb7..d3f414fe67e0 100644
--- a/net/mac80211/rate.c
+++ b/net/mac80211/rate.c
@@ -688,8 +688,15 @@ int rate_control_set_rates(struct ieee80211_hw *hw,
struct ieee80211_sta *pubsta,
struct ieee80211_sta_rates *rates)
{
- struct ieee80211_sta_rates *old = rcu_dereference(pubsta->rates);
+ struct ieee80211_sta_rates *old;
+ /*
+ * mac80211 guarantees that this function will not be called
+ * concurrently, so the following RCU access is safe, even without
+ * extra locking. This can not be checked easily, so we just set
+ * the condition to true.
+ */
+ old = rcu_dereference_protected(pubsta->rates, true);
rcu_assign_pointer(pubsta->rates, rates);
if (old)
kfree_rcu(old, rcu_head);