Re: more tcpdumpinfo for nfs3 problem: aix-server --- linux 2.4.15pre5 client

[Trond Myklebust <trond.myklebust@fys.uio.no>]

>>>>> " " == kuznet  <kuznet@ms2.inr.ac.ru> writes:

     > Hello!
    >> I forgot to add: The socket fasync lists use spinlocking in the
    >> same was as RPC does, with sock_fasync() setting
    >> write_lock_bh(&sk->callback_lock), and sock_def_write_space()
    >> doing read_lock(&sk->callback_lock).
    >>
    >> So that would deadlock with the QDIO driver in the exact same
    >> manner as the RPC stuff (albeit probably a lot less
    >> frequently).

     > Please, elaborate. I do not see any way.


Processor 1                                       Processor 2


(Call QDIO bottom half code)
spin_lock(&QDIO_lock);
                                                write_lock_bh(&sk->callback_lock)
dev_kfree_skb_any()
   -> kfree_skb()
                                                 <QDIO hard interrupt>
     -> write_space()
                                                       ->spin_lock(&QDIO_lock)
                                                              (spins...)
        ->read_lock(&sk->callback_lock);
               (spins)


Deadlock - in exactly the same way as with the xprt code...

Cheers,
   Trond