net_sched: Add qdisc __NET_XMIT_BYPASS flag

Patrick McHardy <kaber@trash.net> noticed that it would be nice to
handle NET_XMIT_BYPASS by NET_XMIT_SUCCESS with an internal qdisc flag
__NET_XMIT_BYPASS and to remove the mapping from dev_queue_xmit().

David Miller <davem@davemloft.net> spotted a serious bug in the first
version of this patch.
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sch_generic.h

@@ -343,14 +343,14 @@ static inline unsigned int qdisc_pkt_len(struct sk_buff *skb)
 	return qdisc_skb_cb(skb)->pkt_len;
 }
 
-#ifdef CONFIG_NET_CLS_ACT
-/* additional qdisc xmit flags */
+/* additional qdisc xmit flags (NET_XMIT_MASK in linux/netdevice.h) */
 enum net_xmit_qdisc_t {
 	__NET_XMIT_STOLEN = 0x00010000,
+	__NET_XMIT_BYPASS = 0x00020000,
 };
 
+#ifdef CONFIG_NET_CLS_ACT
 #define net_xmit_drop_count(e)	((e) & __NET_XMIT_STOLEN ? 0 : 1)
-
 #else
 #define net_xmit_drop_count(e)	(1)
 #endif

net/core/dev.c

@@ -1805,7 +1805,6 @@ int dev_queue_xmit(struct sk_buff *skb)
 
 		spin_unlock(root_lock);
 
-		rc = rc == NET_XMIT_BYPASS ? NET_XMIT_SUCCESS : rc;
 		goto out;
 	}
 

net/sched/sch_atm.c

@@ -457,7 +457,7 @@ drop: __maybe_unused
 		return 0;
 	}
 	tasklet_schedule(&p->task);
-	return NET_XMIT_BYPASS;
+	return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 }
 
 /*

net/sched/sch_cbq.c

@@ -230,7 +230,7 @@ cbq_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
 	    (cl = cbq_class_lookup(q, prio)) != NULL)
 		return cl;
 
-	*qerr = NET_XMIT_BYPASS;
+	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 	for (;;) {
 		int result = 0;
 		defmap = head->defaults;
@@ -377,7 +377,7 @@ cbq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 	q->rx_class = cl;
 #endif
 	if (cl == NULL) {
-		if (ret == NET_XMIT_BYPASS)
+		if (ret & __NET_XMIT_BYPASS)
 			sch->qstats.drops++;
 		kfree_skb(skb);
 		return ret;

net/sched/sch_dsmark.c

@@ -268,7 +268,7 @@ static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 drop:
 	kfree_skb(skb);
 	sch->qstats.drops++;
-	return NET_XMIT_BYPASS;
+	return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 }
 
 static struct sk_buff *dsmark_dequeue(struct Qdisc *sch)

net/sched/sch_hfsc.c

@@ -1159,7 +1159,7 @@ hfsc_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
 		if (cl->level == 0)
 			return cl;
 
-	*qerr = NET_XMIT_BYPASS;
+	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 	tcf = q->root.filter_list;
 	while (tcf && (result = tc_classify(skb, tcf, &res)) >= 0) {
 #ifdef CONFIG_NET_CLS_ACT
@@ -1578,7 +1578,7 @@ hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 
 	cl = hfsc_classify(skb, sch, &err);
 	if (cl == NULL) {
-		if (err == NET_XMIT_BYPASS)
+		if (err & __NET_XMIT_BYPASS)
 			sch->qstats.drops++;
 		kfree_skb(skb);
 		return err;

net/sched/sch_htb.c

@@ -214,7 +214,7 @@ static struct htb_class *htb_classify(struct sk_buff *skb, struct Qdisc *sch,
 	if ((cl = htb_find(skb->priority, sch)) != NULL && cl->level == 0)
 		return cl;
 
-	*qerr = NET_XMIT_BYPASS;
+	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 	tcf = q->filter_list;
 	while (tcf && (result = tc_classify(skb, tcf, &res)) >= 0) {
 #ifdef CONFIG_NET_CLS_ACT
@@ -567,7 +567,7 @@ static int htb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 		}
 #ifdef CONFIG_NET_CLS_ACT
 	} else if (!cl) {
-		if (ret == NET_XMIT_BYPASS)
+		if (ret & __NET_XMIT_BYPASS)
 			sch->qstats.drops++;
 		kfree_skb(skb);
 		return ret;
@@ -612,7 +612,7 @@ static int htb_requeue(struct sk_buff *skb, struct Qdisc *sch)
 		}
 #ifdef CONFIG_NET_CLS_ACT
 	} else if (!cl) {
-		if (ret == NET_XMIT_BYPASS)
+		if (ret & __NET_XMIT_BYPASS)
 			sch->qstats.drops++;
 		kfree_skb(skb);
 		return ret;

net/sched/sch_netem.c

@@ -176,7 +176,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 	if (count == 0) {
 		sch->qstats.drops++;
 		kfree_skb(skb);
-		return NET_XMIT_BYPASS;
+		return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 	}
 
 	skb_orphan(skb);

net/sched/sch_prio.c

@@ -38,7 +38,7 @@ prio_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
 	struct tcf_result res;
 	int err;
 
-	*qerr = NET_XMIT_BYPASS;
+	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 	if (TC_H_MAJ(skb->priority) != sch->handle) {
 		err = tc_classify(skb, q->filter_list, &res);
 #ifdef CONFIG_NET_CLS_ACT
@@ -74,7 +74,7 @@ prio_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 #ifdef CONFIG_NET_CLS_ACT
 	if (qdisc == NULL) {
 
-		if (ret == NET_XMIT_BYPASS)
+		if (ret & __NET_XMIT_BYPASS)
 			sch->qstats.drops++;
 		kfree_skb(skb);
 		return ret;
@@ -103,7 +103,7 @@ prio_requeue(struct sk_buff *skb, struct Qdisc* sch)
 	qdisc = prio_classify(skb, sch, &ret);
 #ifdef CONFIG_NET_CLS_ACT
 	if (qdisc == NULL) {
-		if (ret == NET_XMIT_BYPASS)
+		if (ret & __NET_XMIT_BYPASS)
 			sch->qstats.drops++;
 		kfree_skb(skb);
 		return ret;

net/sched/sch_sfq.c

@@ -171,7 +171,7 @@ static unsigned int sfq_classify(struct sk_buff *skb, struct Qdisc *sch,
 	if (!q->filter_list)
 		return sfq_hash(q, skb) + 1;
 
-	*qerr = NET_XMIT_BYPASS;
+	*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 	result = tc_classify(skb, q->filter_list, &res);
 	if (result >= 0) {
 #ifdef CONFIG_NET_CLS_ACT
@@ -285,7 +285,7 @@ sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 
 	hash = sfq_classify(skb, sch, &ret);
 	if (hash == 0) {
-		if (ret == NET_XMIT_BYPASS)
+		if (ret & __NET_XMIT_BYPASS)
 			sch->qstats.drops++;
 		kfree_skb(skb);
 		return ret;
@@ -339,7 +339,7 @@ sfq_requeue(struct sk_buff *skb, struct Qdisc *sch)
 
 	hash = sfq_classify(skb, sch, &ret);
 	if (hash == 0) {
-		if (ret == NET_XMIT_BYPASS)
+		if (ret & __NET_XMIT_BYPASS)
 			sch->qstats.drops++;
 		kfree_skb(skb);
 		return ret;