Interface iteration in mac80211 can be done without holding any
locks because I converted it to RCU. Initially, I thought this
wouldn't be needed for ieee80211_iterate_active_interfaces but
it's turning out that multi-BSS AP support can be much simpler
in a driver if ieee80211_iterate_active_interfaces can be called
without holding locks. This converts it to use RCU, it adds a
requirement that the callback it invokes cannot sleep.
Signed-off-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
---
include/net/mac80211.h | 3 +--
net/mac80211/util.c | 7 ++++---
2 files changed, 5 insertions(+), 5 deletions(-)
--- everything.orig/include/net/mac80211.h 2007-11-28 01:24:04.030767632 +0100
+++ everything/include/net/mac80211.h 2007-11-28 10:51:18.718922797 +0100
@@ -1408,10 +1408,9 @@ void ieee80211_scan_completed(struct iee
*
* This function iterates over the interfaces associated with a given
* hardware that are currently active and calls the callback for them.
- * Must be called under RTNL.
*
* @hw: the hardware struct of which the interfaces should be iterated over
- * @iterator: the iterator function to call
+ * @iterator: the iterator function to call, cannot sleep
* @data: first argument of the iterator function
*/
void ieee80211_iterate_active_interfaces(struct ieee80211_hw *hw,
--- everything.orig/net/mac80211/util.c 2007-11-28 01:24:24.310766384 +0100
+++ everything/net/mac80211/util.c 2007-11-28 01:26:40.510763509 +0100
@@ -482,10 +482,9 @@ void ieee80211_iterate_active_interfaces
struct ieee80211_local *local = hw_to_local(hw);
struct ieee80211_sub_if_data *sdata;
- ASSERT_RTNL();
+ rcu_read_lock();
- /* we hold the RTNL here so can safely walk the list */
- list_for_each_entry(sdata, &local->interfaces, list) {
+ list_for_each_entry_rcu(sdata, &local->interfaces, list) {
switch (sdata->type) {
case IEEE80211_IF_TYPE_INVALID:
case IEEE80211_IF_TYPE_MNTR:
@@ -504,5 +503,7 @@ void ieee80211_iterate_active_interfaces
iterator(data, sdata->dev->dev_addr,
sdata->dev->ifindex);
}
+
+ rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(ieee80211_iterate_active_interfaces);
-
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