On Fri, 2009-02-27 at 21:07 -0800, Aaron Straus wrote:
> On Feb 27 08:40 PM, Trond Myklebust wrote:
> > > > > static inline int xprt_test_and_set_connected(struct rpc_xprt *xprt)
> > > > > Index: linux-2.6.27.15-2/net/sunrpc/xprtsock.c
> > > > > ===================================================================
> > > > > --- linux-2.6.27.15-2.orig/net/sunrpc/xprtsock.c
> > > > > +++ linux-2.6.27.15-2/net/sunrpc/xprtsock.c
> > > > > @@ -1512,14 +1512,13 @@ static void xs_udp_finish_connecting(str
> > > > > sk->sk_no_check = UDP_CSUM_NORCV;
> > > > > sk->sk_allocation = GFP_ATOMIC;
> > > > >
> > > > > - xprt_set_connected(xprt);
> > > > > -
> > > > > /* Reset to new socket */
> > > > > transport->sock = sock;
> > > > > transport->inet = sk;
> > > > >
> > > > > xs_set_memalloc(xprt);
> > > > >
> > > > > + xprt_set_connected(xprt);
> > > > > write_unlock_bh(&sk->sk_callback_lock);
> > > > > }
> > > > > xs_udp_do_set_buffer_size(xprt);
> > > >
> > >
> > > @@ -588,19 +603,20 @@ static int xs_udp_send_request(struct rpc_task *task)
> > > }
> > >
> > > switch (status) {
> > > + case -EAGAIN:
> > > + xs_nospace(task);
> > > + break;
> > > case -ENETUNREACH:
> > > case -EPIPE:
> > > case -ECONNREFUSED:
> > > /* When the server has died, an ICMP port unreachable message
> > > * prompts ECONNREFUSED. */
> > > - break;
> > > - case -EAGAIN:
> > > - xs_nospace(task);
> > > + clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
> > > break;
> > > default:
> > > + clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
> > > dprintk("RPC: sendmsg returned unrecognized error %d\n",
> > > -status);
> > > - break;
> > > }
> > >
> > > return status;
> > >
> > > This went in to 2.6.26 which was the first time we saw the bug
> > > (2.6.26.3) on kerneloops.
> > >
> > > I don't know if *this* is a bad commit or some other locking changed in
> > > 2.6.26 which tickles the bug.
> >
> > It should be unrelated. If the client managed to get past the call to
> > xs_sendpages(), then the UDP socket must obviously exist already.
>
> PS just to repeat the previous discussion.
>
> It seems like xs_sendpages does check if sock is NULL and returns
> -ENOTCONN in that case.
>
> The problem is that now in xs_udp_send_request falls into the default:
> section of that switch statement and tries to do the:
>
> > > + clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
>
> but sock is NULL, so I think that's the oops.
OK, that makes a lot of sense. We should definitely fix up both
xs_tcp_send_request() and xs_udp_send_request() to deal correctly with
that error.
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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