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Commit f6b3d85f authored by Felix Fietkau's avatar Felix Fietkau Committed by Johannes Berg
Browse files

mac80211: fix spurious RCU warning and update documentation 



Document rx vs tx status concurrency requirements.

Signed-off-by: default avatarFelix Fietkau <nbd@openwrt.org>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 3670946f

include/net/mac80211.h

+8 −4
Original line number Diff line number Diff line
@@ -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

net/mac80211/rate.c

+8 −1
Original line number Diff line number Diff line
@@ -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);