[PATCH] SUNRPC: fix race in in-kernel RPC portmapper client
When submitting a request to a fast portmapper (such as the local rpcbind
daemon), the request can complete before the parent task is even queued up on
xprt->binding. Fix this by queuing before submitting the rpcbind request.
Test plan:
Connectathon locking test with UDP.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/net/sunrpc/pmap_clnt.c b/net/sunrpc/pmap_clnt.c
index 919d5ba..e52afab 100644
--- a/net/sunrpc/pmap_clnt.c
+++ b/net/sunrpc/pmap_clnt.c
@@ -101,11 +101,13 @@
/* Autobind on cloned rpc clients is discouraged */
BUG_ON(clnt->cl_parent != clnt);
- if (xprt_test_and_set_binding(xprt)) {
- task->tk_status = -EACCES; /* tell caller to check again */
- rpc_sleep_on(&xprt->binding, task, NULL, NULL);
- return;
- }
+ /* Put self on queue before sending rpcbind request, in case
+ * pmap_getport_done completes before we return from rpc_run_task */
+ rpc_sleep_on(&xprt->binding, task, NULL, NULL);
+
+ status = -EACCES; /* tell caller to check again */
+ if (xprt_test_and_set_binding(xprt))
+ goto bailout_nofree;
/* Someone else may have bound if we slept */
status = 0;
@@ -134,8 +136,6 @@
goto bailout;
rpc_release_task(child);
- rpc_sleep_on(&xprt->binding, task, NULL, NULL);
-
task->tk_xprt->stat.bind_count++;
return;
