• Eric Dumazet's avatar
    net: sk_dst_cache RCUification · b6c6712a
    Eric Dumazet authored
    With latest CONFIG_PROVE_RCU stuff, I felt more comfortable to make this
    sk->sk_dst_cache is currently protected by a rwlock (sk_dst_lock)
    This rwlock is readlocked for a very small amount of time, and dst
    entries are already freed after RCU grace period. This calls for RCU
    again :)
    This patch converts sk_dst_lock to a spinlock, and use RCU for readers.
    __sk_dst_get() is supposed to be called with rcu_read_lock() or if
    socket locked by user, so use appropriate rcu_dereference_check()
    condition (rcu_read_lock_held() || sock_owned_by_user(sk))
    This patch avoids two atomic ops per tx packet on UDP connected sockets,
    for example, and permits sk_dst_lock to be much less dirtied.
    Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
sock.h 47.5 KB