From 025e6be220e448c02045e8499c7db8ce4bc8eea2 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Tue, 5 Oct 2010 10:41:47 +0200 Subject: mac80211: fix deadlock with multiple interfaces The locking around ieee80211_recalc_smps is buggy -- it cannot acquire another interface's mutex while the iflist mutex is held because another code path could be holding the iface mutex and trying to acquire the iflist mutex. But the locking is also unnecessary, we only check "ifmgd->associated" as a bool, and don't use the pointer (in check_mgd_smps). Reported-by: Ben Greear Signed-off-by: Johannes Berg Signed-off-by: John W. Linville --- net/mac80211/util.c | 20 +++----------------- 1 file changed, 3 insertions(+), 17 deletions(-) (limited to 'net/mac80211/util.c') diff --git a/net/mac80211/util.c b/net/mac80211/util.c index aba025d748e9..4ee8f2b53cb7 100644 --- a/net/mac80211/util.c +++ b/net/mac80211/util.c @@ -1297,16 +1297,12 @@ static int check_mgd_smps(struct ieee80211_if_managed *ifmgd, } /* must hold iflist_mtx */ -void ieee80211_recalc_smps(struct ieee80211_local *local, - struct ieee80211_sub_if_data *forsdata) +void ieee80211_recalc_smps(struct ieee80211_local *local) { struct ieee80211_sub_if_data *sdata; enum ieee80211_smps_mode smps_mode = IEEE80211_SMPS_OFF; int count = 0; - if (forsdata) - lockdep_assert_held(&forsdata->u.mgd.mtx); - lockdep_assert_held(&local->iflist_mtx); /* @@ -1324,18 +1320,8 @@ void ieee80211_recalc_smps(struct ieee80211_local *local, continue; if (sdata->vif.type != NL80211_IFTYPE_STATION) goto set; - if (sdata != forsdata) { - /* - * This nested is ok -- we are holding the iflist_mtx - * so can't get here twice or so. But it's required - * since normally we acquire it first and then the - * iflist_mtx. - */ - mutex_lock_nested(&sdata->u.mgd.mtx, SINGLE_DEPTH_NESTING); - count += check_mgd_smps(&sdata->u.mgd, &smps_mode); - mutex_unlock(&sdata->u.mgd.mtx); - } else - count += check_mgd_smps(&sdata->u.mgd, &smps_mode); + + count += check_mgd_smps(&sdata->u.mgd, &smps_mode); if (count > 1) { smps_mode = IEEE80211_SMPS_OFF; -- cgit v1.2.1