net: Add and use skb_mark_not_on_list().

An SKB is not on a list if skb->next is NULL.

Codify this convention into a helper function and use it
where we are dequeueing an SKB and need to mark it as such.

Signed-off-by: David S. Miller <davem@davemloft.net>

22 files changed, 33 insertions, 28 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 89283b77294d..c4c9e3f5cd9a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1339,6 +1339,11 @@ static inline void skb_zcopy_abort(struct sk_buff *skb)
         }
 }
 
+static inline void skb_mark_not_on_list(struct sk_buff *skb)
+{
+        skb->next = NULL;
+}
+
 /**
  *      skb_queue_empty - check if a queue is empty
  *      @list: queue head
diff --git a/net/core/dev.c b/net/core/dev.c
index ca78dc5a79a3..f76dd7e14dd6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3231,7 +3231,7 @@ struct sk_buff *dev_hard_start_xmit(struct sk_buff *first, struct net_device *de
         while (skb) {
                 struct sk_buff *next = skb->next;
 
-                skb->next = NULL;
+                skb_mark_not_on_list(skb);
                 rc = xmit_one(skb, dev, txq, next != NULL);
                 if (unlikely(!dev_xmit_complete(rc))) {
                         skb->next = next;
@@ -3331,7 +3331,7 @@ struct sk_buff *validate_xmit_skb_list(struct sk_buff *skb, struct net_device *d
 
         for (; skb != NULL; skb = next) {
                 next = skb->next;
-                skb->next = NULL;
+                skb_mark_not_on_list(skb);
 
                 /* in case skb wont be segmented, point to itself */
                 skb->prev = skb;
@@ -5296,7 +5296,7 @@ static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index,
                 if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
                         return;
                 list_del(&skb->list);
-                skb->next = NULL;
+                skb_mark_not_on_list(skb);
                 napi_gro_complete(skb);
                 napi->gro_hash[index].count--;
         }
@@ -5482,7 +5482,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
 
         if (pp) {
                 list_del(&pp->list);
-                pp->next = NULL;
+                skb_mark_not_on_list(pp);
                 napi_gro_complete(pp);
                 napi->gro_hash[hash].count--;
         }
diff --git a/net/core/sock.c b/net/core/sock.c
index 3730eb855095..8537b6ca72c5 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2332,7 +2332,7 @@ static void __release_sock(struct sock *sk)
                         next = skb->next;
                         prefetch(next);
                         WARN_ON_ONCE(skb_dst_is_noref(skb));
-                        skb->next = NULL;
+                        skb_mark_not_on_list(skb);
                         sk_backlog_rcv(sk, skb);
 
                         cond_resched();
diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c
index e7857a8ac86d..09ffbf5ce8fa 100644
--- a/net/ieee802154/6lowpan/reassembly.c
+++ b/net/ieee802154/6lowpan/reassembly.c
@@ -260,7 +260,7 @@ static int lowpan_frag_reasm(struct lowpan_frag_queue *fq, struct sk_buff *prev,
         }
         sub_frag_mem_limit(fq->q.net, sum_truesize);
 
-        head->next = NULL;
+        skb_mark_not_on_list(head);
         head->dev = ldev;
         head->tstamp = fq->q.stamp;
 
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 330f62353b11..cab3e4a5124b 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -623,7 +623,7 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
         sub_frag_mem_limit(qp->q.net, head->truesize);
 
         *nextp = NULL;
-        head->next = NULL;
+        skb_mark_not_on_list(head);
         head->prev = NULL;
         head->dev = dev;
         head->tstamp = qp->q.stamp;
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 3196cf58f418..eba7f3883230 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -535,7 +535,7 @@ static void ip_sublist_rcv_finish(struct list_head *head)
                 /* Handle ip{6}_forward case, as sch_direct_xmit have
                  * another kind of SKB-list usage (see validate_xmit_skb_list)
                  */
-                skb->next = NULL;
+                skb_mark_not_on_list(skb);
                 dst_input(skb);
         }
 }
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 9c4e72e9c60a..c09219e7f230 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -278,7 +278,7 @@ static int ip_finish_output_gso(struct net *net, struct sock *sk,
                 struct sk_buff *nskb = segs->next;
                 int err;
 
-                segs->next = NULL;
+                skb_mark_not_on_list(segs);
                 err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
 
                 if (err && ret == 0)
@@ -684,7 +684,7 @@ int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 
                         skb = frag;
                         frag = skb->next;
-                        skb->next = NULL;
+                        skb_mark_not_on_list(skb);
                 }
 
                 if (err == 0) {
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 16f200f06500..9a8934ac053b 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -727,7 +727,7 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 
                         skb = frag;
                         frag = skb->next;
-                        skb->next = NULL;
+                        skb_mark_not_on_list(skb);
                 }
 
                 kfree(tmp_hdr);
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index 2a14d8b65924..00e20004d241 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -449,7 +449,7 @@ nf_ct_frag6_reasm(struct frag_queue *fq, struct sk_buff *prev,  struct net_devic
         sub_frag_mem_limit(fq->q.net, head->truesize);
 
         head->ignore_df = 1;
-        head->next = NULL;
+        skb_mark_not_on_list(head);
         head->dev = dev;
         head->tstamp = fq->q.stamp;
         ipv6_hdr(head)->payload_len = htons(payload_len);
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 5c5b4f79296e..f1b1ff30fe5b 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -388,7 +388,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
         }
         sub_frag_mem_limit(fq->q.net, sum_truesize);
 
-        head->next = NULL;
+        skb_mark_not_on_list(head);
         head->dev = dev;
         head->tstamp = fq->q.stamp;
         ipv6_hdr(head)->payload_len = htons(payload_len);
diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index ea4ba551abb2..5207eb8a5864 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -764,7 +764,7 @@ __nfqnl_enqueue_packet_gso(struct net *net, struct nfqnl_instance *queue,
                 return ret;
         }
 
-        skb->next = NULL;
+        skb_mark_not_on_list(skb);
 
         entry_seg = nf_queue_entry_dup(entry);
         if (entry_seg) {
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index cfdc199c6351..ee8e7e1d5c0f 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -259,7 +259,7 @@ static void rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
         while (list) {
                 skb = list;
                 list = skb->next;
-                skb->next = NULL;
+                skb_mark_not_on_list(skb);
                 rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
         }
 }
diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c
index c07c30b916d5..dc539295ae65 100644
--- a/net/sched/sch_cake.c
+++ b/net/sched/sch_cake.c
@@ -812,7 +812,7 @@ static struct sk_buff *dequeue_head(struct cake_flow *flow)
 
         if (skb) {
                 flow->head = skb->next;
-                skb->next = NULL;
+                skb_mark_not_on_list(skb);
         }
 
         return skb;
@@ -1252,7 +1252,7 @@ found:
         else
                 flow->head = elig_ack->next;
 
-        elig_ack->next = NULL;
+        skb_mark_not_on_list(elig_ack);
 
         return elig_ack;
 }
@@ -1675,7 +1675,7 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 
                 while (segs) {
                         nskb = segs->next;
-                        segs->next = NULL;
+                        skb_mark_not_on_list(segs);
                         qdisc_skb_cb(segs)->pkt_len = segs->len;
                         cobalt_set_enqueue_time(segs, now);
                         get_cobalt_cb(segs)->adjusted_len = cake_overhead(q,
diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index 4808713c73b9..b27ba36a269c 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -319,7 +319,7 @@ static struct sk_buff *fq_dequeue_head(struct Qdisc *sch, struct fq_flow *flow)
 
         if (skb) {
                 flow->head = skb->next;
-                skb->next = NULL;
+                skb_mark_not_on_list(skb);
                 flow->qlen--;
                 qdisc_qstats_backlog_dec(sch, skb);
                 sch->q.qlen--;
diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index 6c0a9d5dbf94..cd04d40c30b6 100644
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -124,7 +124,7 @@ static inline struct sk_buff *dequeue_head(struct fq_codel_flow *flow)
         struct sk_buff *skb = flow->head;
 
         flow->head = skb->next;
-        skb->next = NULL;
+        skb_mark_not_on_list(skb);
         return skb;
 }
 
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 69078c82963e..a64132a5db36 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -184,7 +184,7 @@ static void try_bulk_dequeue_skb(struct Qdisc *q,
                 skb = nskb;
                 (*packets)++; /* GSO counts as one pkt */
         }
-        skb->next = NULL;
+        skb_mark_not_on_list(skb);
 }
 
 /* This variant of try_bulk_dequeue_skb() makes sure
@@ -210,7 +210,7 @@ static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
                 skb = nskb;
         } while (++cnt < 8);
         (*packets) += cnt;
-        skb->next = NULL;
+        skb_mark_not_on_list(skb);
 }
 
 /* Note that dequeue_skb can possibly return a SKB list (via skb->next).
diff --git a/net/sched/sch_hhf.c b/net/sched/sch_hhf.c
index c3a8388dcdf6..9d6a47697406 100644
--- a/net/sched/sch_hhf.c
+++ b/net/sched/sch_hhf.c
@@ -330,7 +330,7 @@ static struct sk_buff *dequeue_head(struct wdrr_bucket *bucket)
         struct sk_buff *skb = bucket->head;
 
         bucket->head = skb->next;
-        skb->next = NULL;
+        skb_mark_not_on_list(skb);
         return skb;
 }
 
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index b9541ce4d672..506e1960ed7f 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -568,7 +568,7 @@ finish_segs:
         if (segs) {
                 while (segs) {
                         skb2 = segs->next;
-                        segs->next = NULL;
+                        skb_mark_not_on_list(segs);
                         qdisc_skb_cb(segs)->pkt_len = segs->len;
                         last_len = segs->len;
                         rc = qdisc_enqueue(segs, sch, to_free);
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 6f74a426f159..a4530e85bd02 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -162,7 +162,7 @@ static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch,
         nb = 0;
         while (segs) {
                 nskb = segs->next;
-                segs->next = NULL;
+                skb_mark_not_on_list(segs);
                 qdisc_skb_cb(segs)->pkt_len = segs->len;
                 len += segs->len;
                 ret = qdisc_enqueue(segs, q->qdisc, to_free);
diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index 418f03d0be90..91891041e5e1 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -577,7 +577,7 @@ static int tipc_l2_rcv_msg(struct sk_buff *skb, struct net_device *dev,
                 rcu_dereference_rtnl(orig_dev->tipc_ptr);
         if (likely(b && test_bit(0, &b->up) &&
                    (skb->pkt_type <= PACKET_MULTICAST))) {
-                skb->next = NULL;
+                skb_mark_not_on_list(skb);
                 tipc_rcv(dev_net(b->pt.dev), skb, b);
                 rcu_read_unlock();
                 return NET_RX_SUCCESS;
diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c
index 5611b7521020..260fbba4f03e 100644
--- a/net/xfrm/xfrm_device.c
+++ b/net/xfrm/xfrm_device.c
@@ -99,7 +99,7 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur
 
         do {
                 struct sk_buff *nskb = skb2->next;
-                skb2->next = NULL;
+                skb_mark_not_on_list(skb2);
 
                 xo = xfrm_offload(skb2);
                 xo->flags |= XFRM_DEV_RESUME;
diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index 45ba07ab3e4f..2d42cb0c94b8 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -189,7 +189,7 @@ static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb
                 struct sk_buff *nskb = segs->next;
                 int err;
 
-                segs->next = NULL;
+                skb_mark_not_on_list(segs);
                 err = xfrm_output2(net, sk, segs);
 
                 if (unlikely(err)) {