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Subject[v2.6.34-stable 195/213] svcrpc: sends on closed socket should stop immediately
Date
From: "J. Bruce Fields" <bfields@redhat.com>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
If you see a problem with using this for longterm, please comment.
-------------------

commit f06f00a24d76e168ecb38d352126fd203937b601 upstream.

svc_tcp_sendto sets XPT_CLOSE if we fail to transmit the entire reply.
However, the XPT_CLOSE won't be acted on immediately. Meanwhile other
threads could send further replies before the socket is really shut
down. This can manifest as data corruption: for example, if a truncated
read reply is followed by another rpc reply, that second reply will look
to the client like further read data.

Symptoms were data corruption preceded by svc_tcp_sendto logging
something like

kernel: rpc-srv/tcp: nfsd: sent only 963696 when sending 1048708 bytes - shutting down socket

Reported-by: Malahal Naineni <malahal@us.ibm.com>
Tested-by: Malahal Naineni <malahal@us.ibm.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
net/sunrpc/svc_xprt.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 33df29bd8c61..957a7e88e827 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -807,7 +807,8 @@ int svc_send(struct svc_rqst *rqstp)

/* Grab mutex to serialize outgoing data. */
mutex_lock(&xprt->xpt_mutex);
- if (test_bit(XPT_DEAD, &xprt->xpt_flags))
+ if (test_bit(XPT_DEAD, &xprt->xpt_flags)
+ || test_bit(XPT_CLOSE, &xprt->xpt_flags))
len = -ENOTCONN;
else
len = xprt->xpt_ops->xpo_sendto(rqstp);
--
1.8.5.2


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