svn commit: r225913 - head/sys/net80211

[Adrian Chadd]

Author: adrian
Date: Sun Oct  2 02:42:31 2011
New Revision: 225913
URL: http://svn.freebsd.org/changeset/base/225913

Log:
  Fix a panic in the wifi stack when a software beacon miss occurs in the wrong state.
  
  The ieee80211_swbmiss() callout is not called with the ic lock held, so it's
  quite possible the scheduler will run the callout during a state change.
  
  This patch:
  
  * changes the swbmiss callout to be locked by the ic lock
  * enforces the ic lock being held across the beacon vap functions
    by grabbing it inside beacon_miss() and beacon_swmiss().
  
  This ensures that the ic lock is held (and thus the VAP state
  stays constant) during beacon miss and software miss processing.
  Since the callout is removed whilst the ic lock is held, it also
  ensures that the ic lock can't be called during a state change
  or exhibit any race conditions seen above.
  
  Both Edgar and Joel report that this patch fixes the crash and
  doesn't introduce new issues.
  
  Reported by:	Edgar Martinez <emartinez at kbcnetworks.com>
  Reported by:	Joel Dahl <joel at vnode.se>
  Reported by:	emaste

Modified:
  head/sys/net80211/ieee80211_proto.c
  head/sys/net80211/ieee80211_sta.c
  head/sys/net80211/ieee80211_tdma.c

Modified: head/sys/net80211/ieee80211_proto.c
==============================================================================
--- head/sys/net80211/ieee80211_proto.c	Sat Oct  1 23:47:37 2011	(r225912)
+++ head/sys/net80211/ieee80211_proto.c	Sun Oct  2 02:42:31 2011	(r225913)
@@ -193,7 +193,7 @@ ieee80211_proto_vattach(struct ieee80211
 	vap->iv_rtsthreshold = IEEE80211_RTS_DEFAULT;
 	vap->iv_fragthreshold = IEEE80211_FRAG_DEFAULT;
 	vap->iv_bmiss_max = IEEE80211_BMISS_MAX;
-	callout_init(&vap->iv_swbmiss, CALLOUT_MPSAFE);
+	callout_init_mtx(&vap->iv_swbmiss, IEEE80211_LOCK_OBJ(ic), 0);
 	callout_init(&vap->iv_mgtsend, CALLOUT_MPSAFE);
 	TASK_INIT(&vap->iv_nstate_task, 0, ieee80211_newstate_cb, vap);
 	TASK_INIT(&vap->iv_swbmiss_task, 0, beacon_swmiss, vap);
@@ -1403,7 +1403,7 @@ beacon_miss(void *arg, int npending)
 	struct ieee80211com *ic = arg;
 	struct ieee80211vap *vap;
 
-	/* XXX locking */
+	IEEE80211_LOCK(ic);
 	TAILQ_FOREACH(vap, &ic->ic_vaps, iv_next) {
 		/*
 		 * We only pass events through for sta vap's in RUN state;
@@ -1415,18 +1415,21 @@ beacon_miss(void *arg, int npending)
 		    vap->iv_bmiss != NULL)
 			vap->iv_bmiss(vap);
 	}
+	IEEE80211_UNLOCK(ic);
 }
 
 static void
 beacon_swmiss(void *arg, int npending)
 {
 	struct ieee80211vap *vap = arg;
+	struct ieee80211com *ic = vap->iv_ic;
 
-	if (vap->iv_state != IEEE80211_S_RUN)
-		return;
-
-	/* XXX Call multiple times if npending > zero? */
-	vap->iv_bmiss(vap);
+	IEEE80211_LOCK(ic);
+	if (vap->iv_state == IEEE80211_S_RUN) {
+		/* XXX Call multiple times if npending > zero? */
+		vap->iv_bmiss(vap);
+	}
+	IEEE80211_UNLOCK(ic);
 }
 
 /*
@@ -1440,6 +1443,8 @@ ieee80211_swbmiss(void *arg)
 	struct ieee80211vap *vap = arg;
 	struct ieee80211com *ic = vap->iv_ic;
 
+	IEEE80211_LOCK_ASSERT(ic);
+
 	/* XXX sleep state? */
 	KASSERT(vap->iv_state == IEEE80211_S_RUN,
 	    ("wrong state %d", vap->iv_state));

Modified: head/sys/net80211/ieee80211_sta.c
==============================================================================
--- head/sys/net80211/ieee80211_sta.c	Sat Oct  1 23:47:37 2011	(r225912)
+++ head/sys/net80211/ieee80211_sta.c	Sun Oct  2 02:42:31 2011	(r225913)
@@ -109,6 +109,8 @@ sta_beacon_miss(struct ieee80211vap *vap
 {
 	struct ieee80211com *ic = vap->iv_ic;
 
+	IEEE80211_LOCK_ASSERT(ic);
+
 	KASSERT((ic->ic_flags & IEEE80211_F_SCAN) == 0, ("scanning"));
 	KASSERT(vap->iv_state >= IEEE80211_S_RUN,
 	    ("wrong state %s", ieee80211_state_name[vap->iv_state]));

Modified: head/sys/net80211/ieee80211_tdma.c
==============================================================================
--- head/sys/net80211/ieee80211_tdma.c	Sat Oct  1 23:47:37 2011	(r225912)
+++ head/sys/net80211/ieee80211_tdma.c	Sun Oct  2 02:42:31 2011	(r225913)
@@ -285,6 +285,9 @@ static void
 tdma_beacon_miss(struct ieee80211vap *vap)
 {
 	struct ieee80211_tdma_state *ts = vap->iv_tdma;
+	struct ieee80211com *ic = vap->iv_ic;
+
+	IEEE80211_LOCK_ASSERT(ic);
 
 	KASSERT((vap->iv_ic->ic_flags & IEEE80211_F_SCAN) == 0, ("scanning"));
 	KASSERT(vap->iv_state == IEEE80211_S_RUN,