pkt_sched: Add lockdep annotation for qdisc locks

Qdisc locks are initialized in the same function, qdisc_alloc(), so lockdep can't distinguish tx qdisc lock from rx and reports "possible recursive locking detected" when both these locks are taken eg. while using act_mirred with ifb. This looks like a false positive. Anyway, after this patch these locks will be reported more exactly. Reported-by: Denys Fedoryshchenko <[email protected]> Signed-off-by: Jarek Poplawski <[email protected]> Signed-off-by: David S. Miller <[email protected]>
yshchan · Aug 19, 2008 · 25bfcd5 · 25bfcd5
1 parent 8608db0
commit 25bfcd5
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
@@ -27,6 +27,7 @@
 #include <linux/kmod.h>
 #include <linux/list.h>
 #include <linux/hrtimer.h>
+#include <linux/lockdep.h>
 
 #include <net/net_namespace.h>
 #include <net/sock.h>
@@ -707,6 +708,10 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
 	return err;
 }
 
+/* lockdep annotation is needed for ingress; egress gets it only for name */
+static struct lock_class_key qdisc_tx_lock;
+static struct lock_class_key qdisc_rx_lock;
+
 /*
    Allocate and initialize new qdisc.
 
@@ -767,13 +772,15 @@ qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue,
 	if (handle == TC_H_INGRESS) {
 		sch->flags |= TCQ_F_INGRESS;
 		handle = TC_H_MAKE(TC_H_INGRESS, 0);
+		lockdep_set_class(qdisc_lock(sch), &qdisc_rx_lock);
 	} else {
 		if (handle == 0) {
 			handle = qdisc_alloc_handle(dev);
 			err = -ENOMEM;
 			if (handle == 0)
 				goto err_out3;
 		}
+		lockdep_set_class(qdisc_lock(sch), &qdisc_tx_lock);
 	}
 
 	sch->handle = handle;