[NET]: Add memory barrrier to netif_poll_enable()

[linux-2.6] / include / linux / netdevice.h

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c57088f575a37d9961bab86e25bcbcc8658f424f..fea0d9db684604dc1d3b9e98dd25d32172c69291 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -193,13 +193,20 @@ struct hh_cache
 {
        struct hh_cache *hh_next;       /* Next entry                        */
        atomic_t        hh_refcnt;      /* number of users                   */
-       __be16          hh_type;        /* protocol identifier, f.e ETH_P_IP
+/*
+ * We want hh_output, hh_len, hh_lock and hh_data be a in a separate
+ * cache line on SMP.
+ * They are mostly read, but hh_refcnt may be changed quite frequently,
+ * incurring cache line ping pongs.
+ */
+       __be16          hh_type ____cacheline_aligned_in_smp;
+                                       /* protocol identifier, f.e ETH_P_IP
                                          *  NOTE:  For VLANs, this will be the
                                          *  encapuslated type. --BLG
                                          */
        u16             hh_len;         /* length of header */
        int             (*hh_output)(struct sk_buff *skb);
-       rwlock_t        hh_lock;
+       seqlock_t       hh_lock;
 
        /* cached hardware header; allow for machine alignment needs.        */
 #define HH_DATA_MOD    16
@@ -899,6 +906,7 @@ static inline void netif_poll_disable(struct net_device *dev)
 
 static inline void netif_poll_enable(struct net_device *dev)
 {
+       smp_mb__before_clear_bit();
        clear_bit(__LINK_STATE_RX_SCHED, &dev->state);
 }