netfilter: nfnetlink_queue: some optimizations

- Use an atomic_t for id_sequence to avoid a spin_lock/spin_unlock pair

- Group highly modified struct nfqnl_instance fields together

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index 12e1ab3..d05605b 100644 (file)
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -46,17 +46,19 @@ struct nfqnl_instance {
        int peer_pid;
        unsigned int queue_maxlen;
        unsigned int copy_range;
-       unsigned int queue_total;
        unsigned int queue_dropped;
        unsigned int queue_user_dropped;
 
-       unsigned int id_sequence;               /* 'sequence' of pkt ids */
 
        u_int16_t queue_num;                    /* number of this queue */
        u_int8_t copy_mode;
-
-       spinlock_t lock;
-
+/*
+ * Following fields are dirtied for each queued packet,
+ * keep them in same cache line if possible.
+ */
+       spinlock_t      lock;
+       unsigned int    queue_total;
+       atomic_t        id_sequence;            /* 'sequence' of pkt ids */
        struct list_head queue_list;            /* packets in queue */
 };
 
@@ -238,32 +240,24 @@ nfqnl_build_packet_message(struct nfqnl_instance *queue,
 
        outdev = entry->outdev;
 
-       spin_lock_bh(&queue->lock);
-
-       switch ((enum nfqnl_config_mode)queue->copy_mode) {
+       switch ((enum nfqnl_config_mode)ACCESS_ONCE(queue->copy_mode)) {
        case NFQNL_COPY_META:
        case NFQNL_COPY_NONE:
                break;
 
        case NFQNL_COPY_PACKET:
                if (entskb->ip_summed == CHECKSUM_PARTIAL &&
-                   skb_checksum_help(entskb)) {
-                       spin_unlock_bh(&queue->lock);
+                   skb_checksum_help(entskb))
                        return NULL;
-               }
-               if (queue->copy_range == 0
-                   || queue->copy_range > entskb->len)
+
+               data_len = ACCESS_ONCE(queue->copy_range);
+               if (data_len == 0 || data_len > entskb->len)
                        data_len = entskb->len;
-               else
-                       data_len = queue->copy_range;
 
                size += nla_total_size(data_len);
                break;
        }
 
-       entry->id = queue->id_sequence++;
-
-       spin_unlock_bh(&queue->lock);
 
        skb = alloc_skb(size, GFP_ATOMIC);
        if (!skb)
@@ -278,6 +272,7 @@ nfqnl_build_packet_message(struct nfqnl_instance *queue,
        nfmsg->version = NFNETLINK_V0;
        nfmsg->res_id = htons(queue->queue_num);
 
+       entry->id = atomic_inc_return(&queue->id_sequence);
        pmsg.packet_id          = htonl(entry->id);
        pmsg.hw_protocol        = entskb->protocol;
        pmsg.hook               = entry->hook;
@@ -866,7 +861,7 @@ static int seq_show(struct seq_file *s, void *v)
                          inst->peer_pid, inst->queue_total,
                          inst->copy_mode, inst->copy_range,
                          inst->queue_dropped, inst->queue_user_dropped,
-                         inst->id_sequence, 1);
+                         atomic_read(&inst->id_sequence), 1);
 }
 
 static const struct seq_operations nfqnl_seq_ops = {