[IPV4,IPV6]: replace handmade list with hlist in IPv{4,6} reassembly

Both of ipq and frag_queue have *next and **prev, and they can be replaced
with hlist. Thanks Arnaldo Carvalho de Melo for the suggestion.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 30 insertions, 51 deletions

diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index e7d26d9943c2..8ce0ce2ee48e 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -71,7 +71,7 @@ struct ipfrag_skb_cb
 
 /* Describe an entry in the "incomplete datagrams" queue. */
 struct ipq {
-        struct ipq      *next;          /* linked list pointers                 */
+        struct hlist_node list;
         struct list_head lru_list;      /* lru list member                      */
         u32             user;
         u32             saddr;
@@ -89,7 +89,6 @@ struct ipq {
         spinlock_t      lock;
         atomic_t        refcnt;
         struct timer_list timer;        /* when will this queue expire?         */
-        struct ipq      **pprev;
         int             iif;
         struct timeval  stamp;
 };
@@ -99,7 +98,7 @@ struct ipq {
 #define IPQ_HASHSZ      64
 
 /* Per-bucket lock is easy to add now. */
-static struct ipq *ipq_hash[IPQ_HASHSZ];
+static struct hlist_head ipq_hash[IPQ_HASHSZ];
 static DEFINE_RWLOCK(ipfrag_lock);
 static u32 ipfrag_hash_rnd;
 static LIST_HEAD(ipq_lru_list);
@@ -107,9 +106,7 @@ int ip_frag_nqueues = 0;
 
 static __inline__ void __ipq_unlink(struct ipq *qp)
 {
-        if(qp->next)
-                qp->next->pprev = qp->pprev;
-        *qp->pprev = qp->next;
+        hlist_del(&qp->list);
         list_del(&qp->lru_list);
         ip_frag_nqueues--;
 }
@@ -139,27 +136,18 @@ static void ipfrag_secret_rebuild(unsigned long dummy)
         get_random_bytes(&ipfrag_hash_rnd, sizeof(u32));
         for (i = 0; i < IPQ_HASHSZ; i++) {
                 struct ipq *q;
+                struct hlist_node *p, *n;
 
-                q = ipq_hash[i];
-                while (q) {
-                        struct ipq *next = q->next;
+                hlist_for_each_entry_safe(q, p, n, &ipq_hash[i], list) {
                         unsigned int hval = ipqhashfn(q->id, q->saddr,
                                                       q->daddr, q->protocol);
 
                         if (hval != i) {
-                                /* Unlink. */
-                                if (q->next)
-                                        q->next->pprev = q->pprev;
-                                *q->pprev = q->next;
+                                hlist_del(&q->list);
 
                                 /* Relink to new hash chain. */
-                                if ((q->next = ipq_hash[hval]) != NULL)
-                                        q->next->pprev = &q->next;
-                                ipq_hash[hval] = q;
-                                q->pprev = &ipq_hash[hval];
+                                hlist_add_head(&q->list, &ipq_hash[hval]);
                         }
-
-                        q = next;
                 }
         }
         write_unlock(&ipfrag_lock);
@@ -310,14 +298,16 @@ out:
 static struct ipq *ip_frag_intern(unsigned int hash, struct ipq *qp_in)
 {
         struct ipq *qp;
-
+#ifdef CONFIG_SMP
+        struct hlist_node *n;
+#endif
         write_lock(&ipfrag_lock);
 #ifdef CONFIG_SMP
         /* With SMP race we have to recheck hash table, because
          * such entry could be created on other cpu, while we
          * promoted read lock to write lock.
          */
-        for(qp = ipq_hash[hash]; qp; qp = qp->next) {
+        hlist_for_each_entry(qp, n, &ipq_hash[hash], list) {
                 if(qp->id == qp_in->id          &&
                    qp->saddr == qp_in->saddr    &&
                    qp->daddr == qp_in->daddr    &&
@@ -337,10 +327,7 @@ static struct ipq *ip_frag_intern(unsigned int hash, struct ipq *qp_in)
                 atomic_inc(&qp->refcnt);
 
         atomic_inc(&qp->refcnt);
-        if((qp->next = ipq_hash[hash]) != NULL)
-                qp->next->pprev = &qp->next;
-        ipq_hash[hash] = qp;
-        qp->pprev = &ipq_hash[hash];
+        hlist_add_head(&qp->list, &ipq_hash[hash]);
         INIT_LIST_HEAD(&qp->lru_list);
         list_add_tail(&qp->lru_list, &ipq_lru_list);
         ip_frag_nqueues++;
@@ -392,9 +379,10 @@ static inline struct ipq *ip_find(struct iphdr *iph, u32 user)
         __u8 protocol = iph->protocol;
         unsigned int hash = ipqhashfn(id, saddr, daddr, protocol);
         struct ipq *qp;
+        struct hlist_node *n;
 
         read_lock(&ipfrag_lock);
-        for(qp = ipq_hash[hash]; qp; qp = qp->next) {
+        hlist_for_each_entry(qp, n, &ipq_hash[hash], list) {
                 if(qp->id == id         &&
                    qp->saddr == saddr   &&
                    qp->daddr == daddr   &&
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index e4fe9ee484dd..5d316cb72ec9 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -74,7 +74,7 @@ struct ip6frag_skb_cb
 
 struct frag_queue
 {
-        struct frag_queue       *next;
+        struct hlist_node       list;
         struct list_head lru_list;              /* lru list member      */
 
         __u32                   id;             /* fragment id          */
@@ -95,14 +95,13 @@ struct frag_queue
 #define FIRST_IN                2
 #define LAST_IN                 1
         __u16                   nhoffset;
-        struct frag_queue       **pprev;
 };
 
 /* Hash table. */
 
 #define IP6Q_HASHSZ     64
 
-static struct frag_queue *ip6_frag_hash[IP6Q_HASHSZ];
+static struct hlist_head ip6_frag_hash[IP6Q_HASHSZ];
 static DEFINE_RWLOCK(ip6_frag_lock);
 static u32 ip6_frag_hash_rnd;
 static LIST_HEAD(ip6_frag_lru_list);
@@ -110,9 +109,7 @@ int ip6_frag_nqueues = 0;
 
 static __inline__ void __fq_unlink(struct frag_queue *fq)
 {
-        if(fq->next)
-                fq->next->pprev = fq->pprev;
-        *fq->pprev = fq->next;
+        hlist_del(&fq->list);
         list_del(&fq->lru_list);
         ip6_frag_nqueues--;
 }
@@ -163,28 +160,21 @@ static void ip6_frag_secret_rebuild(unsigned long dummy)
         get_random_bytes(&ip6_frag_hash_rnd, sizeof(u32));
         for (i = 0; i < IP6Q_HASHSZ; i++) {
                 struct frag_queue *q;
+                struct hlist_node *p, *n;
 
-                q = ip6_frag_hash[i];
-                while (q) {
-                        struct frag_queue *next = q->next;
+                hlist_for_each_entry_safe(q, p, n, &ip6_frag_hash[i], list) {
                         unsigned int hval = ip6qhashfn(q->id,
                                                        &q->saddr,
                                                        &q->daddr);
 
                         if (hval != i) {
-                                /* Unlink. */
-                                if (q->next)
-                                        q->next->pprev = q->pprev;
-                                *q->pprev = q->next;
+                                hlist_del(&q->list);
 
                                 /* Relink to new hash chain. */
-                                if ((q->next = ip6_frag_hash[hval]) != NULL)
-                                        q->next->pprev = &q->next;
-                                ip6_frag_hash[hval] = q;
-                                q->pprev = &ip6_frag_hash[hval];
-                        }
+                                hlist_add_head(&q->list,
+                                               &ip6_frag_hash[hval]);
 
-                        q = next;
+                        }
                 }
         }
         write_unlock(&ip6_frag_lock);
@@ -337,10 +327,13 @@ static struct frag_queue *ip6_frag_intern(unsigned int hash,
                                           struct frag_queue *fq_in)
 {
         struct frag_queue *fq;
+#ifdef CONFIG_SMP
+        struct hlist_node *n;
+#endif
 
         write_lock(&ip6_frag_lock);
 #ifdef CONFIG_SMP
-        for (fq = ip6_frag_hash[hash]; fq; fq = fq->next) {
+        hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
                 if (fq->id == fq_in->id && 
                     ipv6_addr_equal(&fq_in->saddr, &fq->saddr) &&
                     ipv6_addr_equal(&fq_in->daddr, &fq->daddr)) {
@@ -358,10 +351,7 @@ static struct frag_queue *ip6_frag_intern(unsigned int hash,
                 atomic_inc(&fq->refcnt);
 
         atomic_inc(&fq->refcnt);
-        if((fq->next = ip6_frag_hash[hash]) != NULL)
-                fq->next->pprev = &fq->next;
-        ip6_frag_hash[hash] = fq;
-        fq->pprev = &ip6_frag_hash[hash];
+        hlist_add_head(&fq->list, &ip6_frag_hash[hash]);
         INIT_LIST_HEAD(&fq->lru_list);
         list_add_tail(&fq->lru_list, &ip6_frag_lru_list);
         ip6_frag_nqueues++;
@@ -401,10 +391,11 @@ static __inline__ struct frag_queue *
 fq_find(u32 id, struct in6_addr *src, struct in6_addr *dst)
 {
         struct frag_queue *fq;
+        struct hlist_node *n;
         unsigned int hash = ip6qhashfn(id, src, dst);
 
         read_lock(&ip6_frag_lock);
-        for(fq = ip6_frag_hash[hash]; fq; fq = fq->next) {
+        hlist_for_each_entry(fq, n, &ip6_frag_hash[hash], list) {
                 if (fq->id == id && 
                     ipv6_addr_equal(src, &fq->saddr) &&
                     ipv6_addr_equal(dst, &fq->daddr)) {