Hi Aaron,
I'm just getting back to this.
On Wed, Feb 25, 2009 at 04:17:45PM -0800, Aaron Straus wrote:
> Quick question, do we need a barrier between setting the transport->sock
> and the xprt_set_connected(xprt)?
Yeah, looks that way. That was some interesting reading. Here is the
patch as it stands now. Hopefully I got that right. This has
apparently fixed the problem on ia64 even with out the barriers. rpciod
racing with a write.
> Also, out of curiosity, do you know what changed to introduce the BUG?
I haven't looked into that.
Bruce, can you take this patch? I understand that you're the
maintainer?
Thanks!
Ben
xs_sendpages() returned -ENOTCONN to xs_udp_send_request() and we tried to
clear a bit in transport->sock->flags when sock hadn't been set. With this
change we will instead return earlier in xprt_prepare_transmit() and the rpc
will be retried.
---
include/linux/sunrpc/xprt.h | 9 ++++++++-
net/sunrpc/xprtsock.c | 3 +--
2 files changed, 9 insertions(+), 3 deletions(-)
Index: linux-2.6.27.15-2/include/linux/sunrpc/xprt.h
===================================================================
--- linux-2.6.27.15-2.orig/include/linux/sunrpc/xprt.h
+++ linux-2.6.27.15-2/include/linux/sunrpc/xprt.h
@@ -266,17 +266,24 @@ int xs_swapper(struct rpc_xprt *xprt,
static inline void xprt_set_connected(struct rpc_xprt *xprt)
{
+ smp_wmb();
set_bit(XPRT_CONNECTED, &xprt->state);
}
static inline void xprt_clear_connected(struct rpc_xprt *xprt)
{
clear_bit(XPRT_CONNECTED, &xprt->state);
+ smp_wmb();
}
static inline int xprt_connected(struct rpc_xprt *xprt)
{
- return test_bit(XPRT_CONNECTED, &xprt->state);
+ int connected;
+
+ connected = test_bit(XPRT_CONNECTED, &xprt->state);
+ smp_rmb();
+
+ return 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);
--
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