uwb: fix races between events and neh timers

Always use del_timer_sync() before freeing nehs.  Destroy all nehs after
stopping the radio controller and before cleaning up the reservation
manager.  Handle the timer running after an event has removed the neh.

This fixes various oopses that may occur if a radio controller is removed
while a neh timer is still active.

Signed-off-by: David Vrabel <david.vrabel@csr.com>

1 files changed, 32 insertions, 14 deletions

diff --git a/drivers/uwb/neh.c b/drivers/uwb/neh.c
index 9b4eb64..48b4ece 100644
--- a/drivers/uwb/neh.c
+++ b/drivers/uwb/neh.c
@@ -254,7 +254,6 @@ error_kzalloc:
 
 static void __uwb_rc_neh_rm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
 {
-	del_timer(&neh->timer);
 	__uwb_rc_ctx_put(rc, neh);
 	list_del(&neh->list_node);
 }
@@ -275,6 +274,7 @@ void uwb_rc_neh_rm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
 	__uwb_rc_neh_rm(rc, neh);
 	spin_unlock_irqrestore(&rc->neh_lock, flags);
 
+	del_timer_sync(&neh->timer);
 	uwb_rc_neh_put(neh);
 }
 
@@ -438,9 +438,10 @@ static void uwb_rc_neh_grok_event(struct uwb_rc *rc, struct uwb_rceb *rceb, size
 				rceb->bEventContext, size);
 	} else {
 		neh = uwb_rc_neh_lookup(rc, rceb);
-		if (neh)
+		if (neh) {
+			del_timer_sync(&neh->timer);
 			uwb_rc_neh_cb(neh, rceb, size);
-		else
+		} else
 			dev_warn(dev, "event 0x%02x/%04x/%02x (%zu bytes): nobody cared\n",
 				 rceb->bEventType, le16_to_cpu(rceb->wEvent),
 				 rceb->bEventContext, size);
@@ -562,16 +563,22 @@ EXPORT_SYMBOL_GPL(uwb_rc_neh_grok);
  */
 void uwb_rc_neh_error(struct uwb_rc *rc, int error)
 {
-	struct uwb_rc_neh *neh, *next;
+	struct uwb_rc_neh *neh;
 	unsigned long flags;
 
-	BUG_ON(error >= 0);
-	spin_lock_irqsave(&rc->neh_lock, flags);
-	list_for_each_entry_safe(neh, next, &rc->neh_list, list_node) {
+	for (;;) {
+		spin_lock_irqsave(&rc->neh_lock, flags);
+		if (list_empty(&rc->neh_list)) {
+			spin_unlock_irqrestore(&rc->neh_lock, flags);
+			break;
+		}
+		neh = list_first_entry(&rc->neh_list, struct uwb_rc_neh, list_node);
 		__uwb_rc_neh_rm(rc, neh);
+		spin_unlock_irqrestore(&rc->neh_lock, flags);
+
+		del_timer_sync(&neh->timer);
 		uwb_rc_neh_cb(neh, NULL, error);
 	}
-	spin_unlock_irqrestore(&rc->neh_lock, flags);
 }
 EXPORT_SYMBOL_GPL(uwb_rc_neh_error);
 
@@ -583,10 +590,14 @@ static void uwb_rc_neh_timer(unsigned long arg)
 	unsigned long flags;
 
 	spin_lock_irqsave(&rc->neh_lock, flags);
-	__uwb_rc_neh_rm(rc, neh);
+	if (neh->context)
+		__uwb_rc_neh_rm(rc, neh);
+	else
+		neh = NULL;
 	spin_unlock_irqrestore(&rc->neh_lock, flags);
 
-	uwb_rc_neh_cb(neh, NULL, -ETIMEDOUT);
+	if (neh)
+		uwb_rc_neh_cb(neh, NULL, -ETIMEDOUT);
 }
 
 /** Initializes the @rc's neh subsystem
@@ -605,12 +616,19 @@ void uwb_rc_neh_create(struct uwb_rc *rc)
 void uwb_rc_neh_destroy(struct uwb_rc *rc)
 {
 	unsigned long flags;
-	struct uwb_rc_neh *neh, *next;
+	struct uwb_rc_neh *neh;
 
-	spin_lock_irqsave(&rc->neh_lock, flags);
-	list_for_each_entry_safe(neh, next, &rc->neh_list, list_node) {
+	for (;;) {
+		spin_lock_irqsave(&rc->neh_lock, flags);
+		if (list_empty(&rc->neh_list)) {
+			spin_unlock_irqrestore(&rc->neh_lock, flags);
+			break;
+		}
+		neh = list_first_entry(&rc->neh_list, struct uwb_rc_neh, list_node);
 		__uwb_rc_neh_rm(rc, neh);
+		spin_unlock_irqrestore(&rc->neh_lock, flags);
+
+		del_timer_sync(&neh->timer);
 		uwb_rc_neh_put(neh);
 	}
-	spin_unlock_irqrestore(&rc->neh_lock, flags);
 }