[PATCH 19/34] ipvs: convert dh scheduler to rcu

[Simon Horman <horms@xxxxxxxxxxxx>]

From: Julian Anastasov <ja@xxxxxx>

Use the new add_dest and del_dest methods
to reassign dests.

Signed-off-by: Julian Anastasov <ja@xxxxxx>
Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx>
---
 net/netfilter/ipvs/ip_vs_dh.c |   81 +++++++++++++++++++++++------------------
 1 file changed, 45 insertions(+), 36 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_dh.c b/net/netfilter/ipvs/ip_vs_dh.c
index 7f3b0cc..ebe80f4 100644
--- a/net/netfilter/ipvs/ip_vs_dh.c
+++ b/net/netfilter/ipvs/ip_vs_dh.c
@@ -51,7 +51,7 @@
  *      IPVS DH bucket
  */
 struct ip_vs_dh_bucket {
-       struct ip_vs_dest       *dest;          /* real server (cache) */
+       struct ip_vs_dest __rcu *dest;  /* real server (cache) */
 };
 
 /*
@@ -64,6 +64,10 @@ struct ip_vs_dh_bucket {
 #define IP_VS_DH_TAB_SIZE               (1 << IP_VS_DH_TAB_BITS)
 #define IP_VS_DH_TAB_MASK               (IP_VS_DH_TAB_SIZE - 1)
 
+struct ip_vs_dh_state {
+       struct ip_vs_dh_bucket          buckets[IP_VS_DH_TAB_SIZE];
+       struct rcu_head                 rcu_head;
+};
 
 /*
  *     Returns hash value for IPVS DH entry
@@ -85,10 +89,9 @@ static inline unsigned int ip_vs_dh_hashkey(int af, const 
union nf_inet_addr *ad
  *      Get ip_vs_dest associated with supplied parameters.
  */
 static inline struct ip_vs_dest *
-ip_vs_dh_get(int af, struct ip_vs_dh_bucket *tbl,
-            const union nf_inet_addr *addr)
+ip_vs_dh_get(int af, struct ip_vs_dh_state *s, const union nf_inet_addr *addr)
 {
-       return (tbl[ip_vs_dh_hashkey(af, addr)]).dest;
+       return rcu_dereference(s->buckets[ip_vs_dh_hashkey(af, addr)].dest);
 }
 
 
@@ -96,25 +99,30 @@ ip_vs_dh_get(int af, struct ip_vs_dh_bucket *tbl,
  *      Assign all the hash buckets of the specified table with the service.
  */
 static int
-ip_vs_dh_assign(struct ip_vs_dh_bucket *tbl, struct ip_vs_service *svc)
+ip_vs_dh_reassign(struct ip_vs_dh_state *s, struct ip_vs_service *svc)
 {
        int i;
        struct ip_vs_dh_bucket *b;
        struct list_head *p;
        struct ip_vs_dest *dest;
+       bool empty;
 
-       b = tbl;
+       b = &s->buckets[0];
        p = &svc->destinations;
+       empty = list_empty(p);
        for (i=0; i<IP_VS_DH_TAB_SIZE; i++) {
-               if (list_empty(p)) {
-                       b->dest = NULL;
-               } else {
+               dest = rcu_dereference_protected(b->dest, 1);
+               if (dest)
+                       ip_vs_dest_put(dest);
+               if (empty)
+                       RCU_INIT_POINTER(b->dest, NULL);
+               else {
                        if (p == &svc->destinations)
                                p = p->next;
 
                        dest = list_entry(p, struct ip_vs_dest, n_list);
-                       atomic_inc(&dest->refcnt);
-                       b->dest = dest;
+                       ip_vs_dest_hold(dest);
+                       RCU_INIT_POINTER(b->dest, dest);
 
                        p = p->next;
                }
@@ -127,16 +135,18 @@ ip_vs_dh_assign(struct ip_vs_dh_bucket *tbl, struct 
ip_vs_service *svc)
 /*
  *      Flush all the hash buckets of the specified table.
  */
-static void ip_vs_dh_flush(struct ip_vs_dh_bucket *tbl)
+static void ip_vs_dh_flush(struct ip_vs_dh_state *s)
 {
        int i;
        struct ip_vs_dh_bucket *b;
+       struct ip_vs_dest *dest;
 
-       b = tbl;
+       b = &s->buckets[0];
        for (i=0; i<IP_VS_DH_TAB_SIZE; i++) {
-               if (b->dest) {
-                       atomic_dec(&b->dest->refcnt);
-                       b->dest = NULL;
+               dest = rcu_dereference_protected(b->dest, 1);
+               if (dest) {
+                       ip_vs_dest_put(dest);
+                       RCU_INIT_POINTER(b->dest, NULL);
                }
                b++;
        }
@@ -145,21 +155,20 @@ static void ip_vs_dh_flush(struct ip_vs_dh_bucket *tbl)
 
 static int ip_vs_dh_init_svc(struct ip_vs_service *svc)
 {
-       struct ip_vs_dh_bucket *tbl;
+       struct ip_vs_dh_state *s;
 
        /* allocate the DH table for this service */
-       tbl = kmalloc(sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE,
-                     GFP_KERNEL);
-       if (tbl == NULL)
+       s = kzalloc(sizeof(struct ip_vs_dh_state), GFP_KERNEL);
+       if (s == NULL)
                return -ENOMEM;
 
-       svc->sched_data = tbl;
+       svc->sched_data = s;
        IP_VS_DBG(6, "DH hash table (memory=%Zdbytes) allocated for "
                  "current service\n",
                  sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE);
 
-       /* assign the hash buckets with the updated service */
-       ip_vs_dh_assign(tbl, svc);
+       /* assign the hash buckets with current dests */
+       ip_vs_dh_reassign(s, svc);
 
        return 0;
 }
@@ -167,13 +176,13 @@ static int ip_vs_dh_init_svc(struct ip_vs_service *svc)
 
 static int ip_vs_dh_done_svc(struct ip_vs_service *svc)
 {
-       struct ip_vs_dh_bucket *tbl = svc->sched_data;
+       struct ip_vs_dh_state *s = svc->sched_data;
 
        /* got to clean up hash buckets here */
-       ip_vs_dh_flush(tbl);
+       ip_vs_dh_flush(s);
 
        /* release the table itself */
-       kfree(svc->sched_data);
+       kfree_rcu(s, rcu_head);
        IP_VS_DBG(6, "DH hash table (memory=%Zdbytes) released\n",
                  sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE);
 
@@ -181,15 +190,13 @@ static int ip_vs_dh_done_svc(struct ip_vs_service *svc)
 }
 
 
-static int ip_vs_dh_update_svc(struct ip_vs_service *svc)
+static int ip_vs_dh_dest_changed(struct ip_vs_service *svc,
+                                struct ip_vs_dest *dest)
 {
-       struct ip_vs_dh_bucket *tbl = svc->sched_data;
-
-       /* got to clean up hash buckets here */
-       ip_vs_dh_flush(tbl);
+       struct ip_vs_dh_state *s = svc->sched_data;
 
        /* assign the hash buckets with the updated service */
-       ip_vs_dh_assign(tbl, svc);
+       ip_vs_dh_reassign(s, svc);
 
        return 0;
 }
@@ -212,19 +219,20 @@ static struct ip_vs_dest *
 ip_vs_dh_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
 {
        struct ip_vs_dest *dest;
-       struct ip_vs_dh_bucket *tbl;
+       struct ip_vs_dh_state *s;
        struct ip_vs_iphdr iph;
 
        ip_vs_fill_iph_addr_only(svc->af, skb, &iph);
 
        IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
 
-       tbl = (struct ip_vs_dh_bucket *)svc->sched_data;
-       dest = ip_vs_dh_get(svc->af, tbl, &iph.daddr);
+       s = (struct ip_vs_dh_state *) svc->sched_data;
+       dest = ip_vs_dh_get(svc->af, s, &iph.daddr);
        if (!dest
            || !(dest->flags & IP_VS_DEST_F_AVAILABLE)
            || atomic_read(&dest->weight) <= 0
            || is_overloaded(dest)) {
+               ip_vs_scheduler_err(svc, "no destination available");
                return NULL;
        }
 
@@ -248,7 +256,8 @@ static struct ip_vs_scheduler ip_vs_dh_scheduler =
        .n_list =               LIST_HEAD_INIT(ip_vs_dh_scheduler.n_list),
        .init_service =         ip_vs_dh_init_svc,
        .done_service =         ip_vs_dh_done_svc,
-       .update_service =       ip_vs_dh_update_svc,
+       .add_dest =             ip_vs_dh_dest_changed,
+       .del_dest =             ip_vs_dh_dest_changed,
        .schedule =             ip_vs_dh_schedule,
 };
 
-- 
1.7.10.4

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