The following commit has been merged in the linux branch: commit d20ef63d32461332958661df73e21c0ca42601b0 Author: Johannes Berg johannes@sipsolutions.net Date: Sun Oct 11 15:10:40 2009 +0200

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

diff --git a/include/net/mac80211.h b/include/net/mac80211.h index 466859b..c75b960 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 865fbc0..7170bf4 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;