Hi Trond,
On Feb 27 07:37 PM, Trond Myklebust wrote:
> NACK. If you need a memory barrier, put it in the UDP case only (and
> justify why). The TCP case sets and clears the above in the
> connect/disconnect softirqs and so does not require them.
>
> I certainly see no reason whatsoever for adding memory barriers to
> xprt_connected() or xprt_clear_connected().
>
> > 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);
>
> Please move that call to xprt_set_connected() outside the if statement.
> We want to set the connected flag unconditionally here.
FYI, I've been digging a bit. This commit adds the clearing of the
bits:
commit b6ddf64ffe9d59577a9176856bb6fe69a539f573
Author: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Date: Thu Apr 17 18:52:19 2008 -0400
SUNRPC: Fix up xprt_write_space()
<snip>
@@ -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.
Hope it helps. Have a good weekend all!
=a=
--
===================
Aaron Straus
aaron@xxxxxxxxxxxxx
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