Hi Trond-
On Apr 19, 2008, at 4:40 PM, Trond Myklebust wrote:
We want to ensure that req->rq_private_buf.len is updated before
req->rq_received, so that call_decode() doesn't use an old value for
req->rq_rcv_buf.len.
In 'call_decode()' itself, instead of using task->tk_status (which
is set
using req->rq_received) must use the actual value of
req->rq_private_buf.len when deciding whether or not the received
RPC reply
is too short.
Finally ensure that we set req->rq_rcv_buf.len to zero when retrying a
request. A typo meant that we were resetting req->rq_private_buf.len
in
call_decode(), and then clobbering that value with the old
rq_rcv_buf.len
again in xprt_transmit().
After staring at this for a while, the interaction between
xprt_complete_rqst and call_decode isn't clear to me.
I take it there is no guarantee that the xdr_buf fields and
rq_received are completely updated before the task is awoken and
call_decode runs?
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
---
net/sunrpc/clnt.c | 26 +++++++++++++-------------
net/sunrpc/xprt.c | 3 ++-
2 files changed, 15 insertions(+), 14 deletions(-)
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 0c29792..57663a4 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -1195,18 +1195,6 @@ call_decode(struct rpc_task *task)
task->tk_flags &= ~RPC_CALL_MAJORSEEN;
}
- if (task->tk_status < 12) {
- if (!RPC_IS_SOFT(task)) {
- task->tk_action = call_bind;
- clnt->cl_stats->rpcretrans++;
- goto out_retry;
- }
- dprintk("RPC: %s: too small RPC reply size (%d bytes)\n",
- clnt->cl_protname, task->tk_status);
- task->tk_action = call_timeout;
- goto out_retry;
- }
-
/*
* Ensure that we see all writes made by xprt_complete_rqst()
* before it changed req->rq_received.
@@ -1218,6 +1206,18 @@ call_decode(struct rpc_task *task)
WARN_ON(memcmp(&req->rq_rcv_buf, &req->rq_private_buf,
sizeof(req->rq_rcv_buf)) != 0);
+ if (req->rq_rcv_buf.len < 12) {
+ if (!RPC_IS_SOFT(task)) {
+ task->tk_action = call_bind;
+ clnt->cl_stats->rpcretrans++;
+ goto out_retry;
+ }
+ dprintk("RPC: %s: too small RPC reply size (%d bytes)\n",
+ clnt->cl_protname, task->tk_status);
+ task->tk_action = call_timeout;
+ goto out_retry;
+ }
+
/* Verify the RPC header */
p = call_verify(task);
if (IS_ERR(p)) {
@@ -1239,7 +1239,7 @@ out_retry:
task->tk_status = 0;
/* Note: call_verify() may have freed the RPC slot */
if (task->tk_rqstp == req) {
- req->rq_received = req->rq_private_buf.len = 0;
+ req->rq_received = req->rq_rcv_buf.len = 0;
if (task->tk_client->cl_discrtry)
xprt_force_disconnect(task->tk_xprt);
}
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 3ba64f9..5110a4e 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -757,9 +757,10 @@ void xprt_complete_rqst(struct rpc_task *task,
int copied)
task->tk_rtt = (long)jiffies - req->rq_xtime;
list_del_init(&req->rq_list);
+ req->rq_private_buf.len = copied;
/* Ensure all writes are done before we update req->rq_received */
smp_wmb();
- req->rq_received = req->rq_private_buf.len = copied;
+ req->rq_received = copied;
rpc_wake_up_queued_task(&xprt->pending, task);
}
EXPORT_SYMBOL_GPL(xprt_complete_rqst);
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--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
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