tunnel: hh_cache access cleanup

Following patch cleanup hh_cache access by avoiding hh pointer fetching
most of time. Now hh is read and checked at beginning of function. All
hh->hh_len access are done inside hh_lock.
This is required cleanup for next patch which adds support for kernel
3.1.

Suggested-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: Pravin Shelar <pshelar@nicira.com>
Acked-by: Jesse Gross <jesse@nicira.com>

diff --git a/datapath/tunnel.c b/datapath/tunnel.c
index 8edff06..78358b4 100644 (file)
--- a/datapath/tunnel.c
+++ b/datapath/tunnel.c
@@ -743,7 +743,13 @@ static inline void *get_cached_header(const struct tnl_cache *cache)
 static inline bool check_cache_valid(const struct tnl_cache *cache,
                                     const struct tnl_mutable_config *mutable)
 {
-       return cache &&
+       struct hh_cache *hh;
+
+       if (!cache)
+               return false;
+
+       hh = rt_dst(cache->rt).hh;
+       return hh &&
 #ifdef NEED_CACHE_TIMEOUT
                time_before(jiffies, cache->expiration) &&
 #endif
@@ -751,7 +757,7 @@ static inline bool check_cache_valid(const struct tnl_cache *cache,
                atomic_read(&init_net.ipv4.rt_genid) == cache->rt->rt_genid &&
 #endif
 #ifdef HAVE_HH_SEQ
-               rt_dst(cache->rt).hh->hh_lock.sequence == cache->hh_seq &&
+               hh->hh_lock.sequence == cache->hh_seq &&
 #endif
                mutable->seq == cache->mutable_seq &&
                (!is_internal_dev(rt_dst(cache->rt).dev) ||
@@ -791,25 +797,28 @@ static void cache_cleaner(struct work_struct *work)
 }
 
 static inline void create_eth_hdr(struct tnl_cache *cache,
-                                 const struct rtable *rt)
+                                 struct hh_cache *hh)
 {
        void *cache_data = get_cached_header(cache);
-       int hh_len = rt_dst(rt).hh->hh_len;
-       int hh_off = HH_DATA_ALIGN(rt_dst(rt).hh->hh_len) - hh_len;
+       int hh_off;
 
 #ifdef HAVE_HH_SEQ
        unsigned hh_seq;
 
        do {
-               hh_seq = read_seqbegin(&rt_dst(rt).hh->hh_lock);
-               memcpy(cache_data, (void *)rt_dst(rt).hh->hh_data + hh_off, hh_len);
-       } while (read_seqretry(&rt_dst(rt).hh->hh_lock, hh_seq));
+               hh_seq = read_seqbegin(&hh->hh_lock);
+               hh_off = HH_DATA_ALIGN(hh->hh_len) - hh->hh_len;
+               memcpy(cache_data, (void *)hh->hh_data + hh_off, hh->hh_len);
+               cache->hh_len = hh->hh_len;
+       } while (read_seqretry(&hh->hh_lock, hh_seq));
 
        cache->hh_seq = hh_seq;
 #else
-       read_lock(&rt_dst(rt).hh->hh_lock);
-       memcpy(cache_data, (void *)rt_dst(rt).hh->hh_data + hh_off, hh_len);
-       read_unlock(&rt_dst(rt).hh->hh_lock);
+       read_lock(&hh->hh_lock);
+       hh_off = HH_DATA_ALIGN(hh->hh_len) - hh->hh_len;
+       memcpy(cache_data, (void *)hh->hh_data + hh_off, hh->hh_len);
+       cache->hh_len = hh->hh_len;
+       read_unlock(&hh->hh_lock);
 #endif
 }
 
@@ -821,6 +830,7 @@ static struct tnl_cache *build_cache(struct vport *vport,
        struct tnl_cache *cache;
        void *cache_data;
        int cache_len;
+       struct hh_cache *hh;
 
        if (!(mutable->flags & TNL_F_HDR_CACHE))
                return NULL;
@@ -829,7 +839,9 @@ static struct tnl_cache *build_cache(struct vport *vport,
         * If there is no entry in the ARP cache or if this device does not
         * support hard header caching just fall back to the IP stack.
         */
-       if (!rt_dst(rt).hh)
+
+       hh = rt_dst(rt).hh;
+       if (!hh)
                return NULL;
 
        /*
@@ -845,17 +857,16 @@ static struct tnl_cache *build_cache(struct vport *vport,
        else
                cache = NULL;
 
-       cache_len = rt_dst(rt).hh->hh_len + mutable->tunnel_hlen;
+       cache_len = LL_RESERVED_SPACE(rt_dst(rt).dev) + mutable->tunnel_hlen;
 
        cache = kzalloc(ALIGN(sizeof(struct tnl_cache), CACHE_DATA_ALIGN) +
                        cache_len, GFP_ATOMIC);
        if (!cache)
                goto unlock;
 
-       cache->len = cache_len;
-
-       create_eth_hdr(cache, rt);
-       cache_data = get_cached_header(cache) + rt_dst(rt).hh->hh_len;
+       create_eth_hdr(cache, hh);
+       cache_data = get_cached_header(cache) + cache->hh_len;
+       cache->len = cache->hh_len + mutable->tunnel_hlen;
 
        create_tunnel_header(vport, mutable, rt, cache_data);
 
@@ -1181,7 +1192,7 @@ int tnl_send(struct vport *vport, struct sk_buff *skb)
                        skb_push(skb, cache->len);
                        memcpy(skb->data, get_cached_header(cache), cache->len);
                        skb_reset_mac_header(skb);
-                       skb_set_network_header(skb, rt_dst(rt).hh->hh_len);
+                       skb_set_network_header(skb, cache->hh_len);
 
                } else {
                        skb_push(skb, mutable->tunnel_hlen);

diff --git a/datapath/tunnel.h b/datapath/tunnel.h
index 8d20c77..9211740 100644 (file)
--- a/datapath/tunnel.h
+++ b/datapath/tunnel.h
@@ -148,6 +148,7 @@ struct tnl_cache {
        struct rcu_head rcu;
 
        int len;                /* Length of data to be memcpy'd from cache. */
+       int hh_len;             /* Hardware hdr length, cached from hh_cache. */
 
        /* Sequence number of mutable->seq from which this cache was generated. */
        unsigned mutable_seq;