Merge branch 'skb_list_walk_safe-refactoring'

Jason A. Donenfeld says:

====================
skb_list_walk_safe refactoring for net/*'s skb_gso_segment usage

This patchset adjusts all return values of skb_gso_segment in net/* to
use the new skb_list_walk_safe helper.

First we fix a minor bug in the helper macro that didn't come up in the
last patchset's uses. Then we adjust several cases throughout net/. The
xfrm changes were a bit hairy, but doable. Reading and thinking about
the code in mac80211 indicates a memory leak, which the commit
addresses. All the other cases were pretty trivial.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -1479,9 +1479,9 @@ static inline void skb_mark_not_on_list(struct sk_buff *skb)
 }
 
 /* Iterate through singly-linked GSO fragments of an skb. */
-#define skb_list_walk_safe(first, skb, next)                                   \
-	for ((skb) = (first), (next) = (skb) ? (skb)->next : NULL; (skb);      \
-	     (skb) = (next), (next) = (skb) ? (skb)->next : NULL)
+#define skb_list_walk_safe(first, skb, next_skb)                               \
+	for ((skb) = (first), (next_skb) = (skb) ? (skb)->next : NULL; (skb);  \
+	     (skb) = (next_skb), (next_skb) = (skb) ? (skb)->next : NULL)
 
 static inline void skb_list_del_init(struct sk_buff *skb)
 {

net/ipv4/ip_output.c

@@ -240,8 +240,8 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
 static int ip_finish_output_gso(struct net *net, struct sock *sk,
 				struct sk_buff *skb, unsigned int mtu)
 {
+	struct sk_buff *segs, *nskb;
 	netdev_features_t features;
-	struct sk_buff *segs;
 	int ret = 0;
 
 	/* common case: seglen is <= mtu
@@ -272,8 +272,7 @@ static int ip_finish_output_gso(struct net *net, struct sock *sk,
 
 	consume_skb(skb);
 
-	do {
-		struct sk_buff *nskb = segs->next;
+	skb_list_walk_safe(segs, segs, nskb) {
 		int err;
 
 		skb_mark_not_on_list(segs);
@@ -281,8 +280,7 @@ static int ip_finish_output_gso(struct net *net, struct sock *sk,
 
 		if (err && ret == 0)
 			ret = err;
-		segs = nskb;
-	} while (segs);
+	}
 
 	return ret;
 }

net/ipv4/udp.c

@@ -2104,8 +2104,7 @@ static int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 	BUILD_BUG_ON(sizeof(struct udp_skb_cb) > SKB_SGO_CB_OFFSET);
 	__skb_push(skb, -skb_mac_offset(skb));
 	segs = udp_rcv_segment(sk, skb, true);
-	for (skb = segs; skb; skb = next) {
-		next = skb->next;
+	skb_list_walk_safe(segs, skb, next) {
 		__skb_pull(skb, skb_transport_offset(skb));
 		ret = udp_queue_rcv_one_skb(sk, skb);
 		if (ret > 0)

net/ipv6/udp.c

@@ -690,8 +690,7 @@ static int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 
 	__skb_push(skb, -skb_mac_offset(skb));
 	segs = udp_rcv_segment(sk, skb, false);
-	for (skb = segs; skb; skb = next) {
-		next = skb->next;
+	skb_list_walk_safe(segs, skb, next) {
 		__skb_pull(skb, skb_transport_offset(skb));
 
 		ret = udpv6_queue_rcv_one_skb(sk, skb);

net/mac80211/tx.c

@@ -3949,18 +3949,15 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
 		}
 	}
 
-	next = skb;
-	while (next) {
-		skb = next;
-		next = skb->next;
-
-		skb->prev = NULL;
-		skb->next = NULL;
+	skb_list_walk_safe(skb, skb, next) {
+		skb_mark_not_on_list(skb);
 
 		skb = ieee80211_build_hdr(sdata, skb, info_flags,
 					  sta, ctrl_flags);
-		if (IS_ERR(skb))
+		if (IS_ERR(skb)) {
+			kfree_skb_list(next);
 			goto out;
+		}
 
 		ieee80211_tx_stats(dev, skb->len);
 

net/netfilter/nfnetlink_queue.c

@@ -778,7 +778,7 @@ nfqnl_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum)
 {
 	unsigned int queued;
 	struct nfqnl_instance *queue;
-	struct sk_buff *skb, *segs;
+	struct sk_buff *skb, *segs, *nskb;
 	int err = -ENOBUFS;
 	struct net *net = entry->state.net;
 	struct nfnl_queue_net *q = nfnl_queue_pernet(net);
@@ -815,8 +815,7 @@ nfqnl_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum)
 		goto out_err;
 	queued = 0;
 	err = 0;
-	do {
-		struct sk_buff *nskb = segs->next;
+	skb_list_walk_safe(segs, segs, nskb) {
 		if (err == 0)
 			err = __nfqnl_enqueue_packet_gso(net, queue,
 							segs, entry);
@@ -824,8 +823,7 @@ nfqnl_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum)
 			queued++;
 		else
 			kfree_skb(segs);
-		segs = nskb;
-	} while (segs);
+	}
 
 	if (queued) {
 		if (err) /* some segments are already queued */

net/openvswitch/datapath.c

@@ -321,8 +321,7 @@ static int queue_gso_packets(struct datapath *dp, struct sk_buff *skb,
 	}
 
 	/* Queue all of the segments. */
-	skb = segs;
-	do {
+	skb_list_walk_safe(segs, skb, nskb) {
 		if (gso_type & SKB_GSO_UDP && skb != segs)
 			key = &later_key;
 
@@ -330,17 +329,15 @@ static int queue_gso_packets(struct datapath *dp, struct sk_buff *skb,
 		if (err)
 			break;
 
-	} while ((skb = skb->next));
+	}
 
 	/* Free all of the segments. */
-	skb = segs;
-	do {
-		nskb = skb->next;
+	skb_list_walk_safe(segs, skb, nskb) {
 		if (err)
 			kfree_skb(skb);
 		else
 			consume_skb(skb);
-	} while ((skb = nskb));
+	}
 	return err;
 }
 

net/sched/sch_cake.c

@@ -1682,8 +1682,7 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 		if (IS_ERR_OR_NULL(segs))
 			return qdisc_drop(skb, sch, to_free);
 
-		while (segs) {
-			nskb = segs->next;
+		skb_list_walk_safe(segs, segs, nskb) {
 			skb_mark_not_on_list(segs);
 			qdisc_skb_cb(segs)->pkt_len = segs->len;
 			cobalt_set_enqueue_time(segs, now);
@@ -1696,7 +1695,6 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 			slen += segs->len;
 			q->buffer_used += segs->truesize;
 			b->packets++;
-			segs = nskb;
 		}
 
 		/* stats */

net/sched/sch_tbf.c

@@ -155,8 +155,7 @@ static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch,
 		return qdisc_drop(skb, sch, to_free);
 
 	nb = 0;
-	while (segs) {
-		nskb = segs->next;
+	skb_list_walk_safe(segs, segs, nskb) {
 		skb_mark_not_on_list(segs);
 		qdisc_skb_cb(segs)->pkt_len = segs->len;
 		len += segs->len;
@@ -167,7 +166,6 @@ static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch,
 		} else {
 			nb++;
 		}
-		segs = nskb;
 	}
 	sch->q.qlen += nb;
 	if (nb > 1)

net/xfrm/xfrm_device.c

@@ -78,7 +78,7 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur
 	int err;
 	unsigned long flags;
 	struct xfrm_state *x;
-	struct sk_buff *skb2;
+	struct sk_buff *skb2, *nskb;
 	struct softnet_data *sd;
 	netdev_features_t esp_features = features;
 	struct xfrm_offload *xo = xfrm_offload(skb);
@@ -148,11 +148,7 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur
 		return skb;
 	}
 
-	skb2 = skb;
-
-	do {
-		struct sk_buff *nskb = skb2->next;
-
+	skb_list_walk_safe(skb, skb2, nskb) {
 		esp_features |= skb->dev->gso_partial_features;
 		skb_mark_not_on_list(skb2);
 
@@ -176,14 +172,11 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur
 			if (!skb)
 				return NULL;
 
-			goto skip_push;
+			continue;
 		}
 
 		skb_push(skb2, skb2->data - skb_mac_header(skb2));
-
-skip_push:
-		skb2 = nskb;
-	} while (skb2);
+	}
 
 	return skb;
 }

net/xfrm/xfrm_output.c

@@ -533,7 +533,7 @@ static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
 
 static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
-	struct sk_buff *segs;
+	struct sk_buff *segs, *nskb;
 
 	BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
 	BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET);
@@ -544,8 +544,7 @@ static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb
 	if (segs == NULL)
 		return -EINVAL;
 
-	do {
-		struct sk_buff *nskb = segs->next;
+	skb_list_walk_safe(segs, segs, nskb) {
 		int err;
 
 		skb_mark_not_on_list(segs);
@@ -555,9 +554,7 @@ static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb
 			kfree_skb_list(nskb);
 			return err;
 		}
-
-		segs = nskb;
-	} while (segs);
+	}
 
 	return 0;
 }