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authorJohannes Berg <johannes@sipsolutions.net>2009-10-11 15:10:40 +0200
committerJohn W. Linville <linville@tuxdriver.com>2009-10-12 15:55:53 -0400
commitd20ef63d32461332958661df73e21c0ca42601b0 (patch)
treeb63f50f6086cacd9597490459f9febe289ba8c0d
parentedbfdcceb41c0cbfc1dd2cd28af2272190be47ad (diff)
mac80211: document ieee80211_rx() context requirement
ieee80211_rx() must be called with softirqs disabled since the networking stack requires this for netif_rx() and some code in mac80211 can assume that it can not be processing its own tasklet and this call at the same time. It may be possible to remove this requirement after a careful audit of mac80211 and doing any needed locking improvements in it along with disabling softirqs around netif_rx(). An alternative might be to push all packet processing to process context in mac80211, instead of to the tasklet, and add other synchronisation. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
-rw-r--r--include/net/mac80211.h2
-rw-r--r--net/mac80211/rx.c2
2 files changed, 4 insertions, 0 deletions
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 466859b285e..c75b960c8ac 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1669,6 +1669,8 @@ void ieee80211_restart_hw(struct ieee80211_hw *hw);
* to this function and ieee80211_rx_irqsafe() may not be mixed for a
* single hardware.
*
+ * Note that right now, this function must be called with softirqs disabled.
+ *
* @hw: the hardware this frame came in on
* @skb: the buffer to receive, owned by mac80211 after this call
*/
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 865fbc09be1..7170bf4565a 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2453,6 +2453,8 @@ void ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb)
struct ieee80211_supported_band *sband;
struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
+ WARN_ON_ONCE(softirq_count() == 0);
+
if (WARN_ON(status->band < 0 ||
status->band >= IEEE80211_NUM_BANDS))
goto drop;