• Denis V. Lunev's avatar
    [NET]: make netlink user -> kernel interface synchronious · cd40b7d3
    Denis V. Lunev authored
    This patch make processing netlink user -> kernel messages synchronious.
    This change was inspired by the talk with Alexey Kuznetsov about current
    netlink messages processing. He says that he was badly wrong when introduced 
    asynchronious user -> kernel communication.
    
    The call netlink_unicast is the only path to send message to the kernel
    netlink socket. But, unfortunately, it is also used to send data to the
    user.
    
    Before this change the user message has been attached to the socket queue
    and sk->sk_data_ready was called. The process has been blocked until all
    pending messages were processed. The bad thing is that this processing
    may occur in the arbitrary process context.
    
    This patch changes nlk->data_ready callback to get 1 skb and force packet
    processing right in the netlink_unicast.
    
    Kernel -> user path in netlink_unicast remains untouched.
    
    EINTR processing for in netlink_run_queue was changed. It forces rtnl_lock
    drop, but the process remains in the cycle until the message will be fully
    processed. So, there is no need to use this kludges now.
    Signed-off-by: default avatarDenis V. Lunev <den@openvz.org>
    Acked-by: default avatarAlexey Kuznetsov <kuznet@ms2.inr.ac.ru>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    cd40b7d3
af_netlink.c 42.7 KB