Commit 823c73d0 authored by Chuck Lever's avatar Chuck Lever Committed by Anna Schumaker
Browse files

SUNRPC: Unset RPC_TASK_NO_RETRANS_TIMEOUT for NULL RPCs 



In some rare failure modes, the server is actually reading the
transport, but then just dropping the requests on the floor.
TCP_USER_TIMEOUT cannot detect that case.

Prevent such a stuck server from pinning client resources
indefinitely by ensuring that certain idempotent requests
(such as NULL) can time out even if the connection is still
operational.

Otherwise rpc_bind_new_program(), gss_destroy_cred(), or
rpc_clnt_test_and_add_xprt() can wait forever.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent aede5172

net/sunrpc/clnt.c

+14 −1
Original line number Diff line number Diff line
@@ -2694,6 +2694,18 @@ static const struct rpc_procinfo rpcproc_null = { 
	.p_decode = rpcproc_decode_null,

};



static void

rpc_null_call_prepare(struct rpc_task *task, void *data)

{

	task->tk_flags &= ~RPC_TASK_NO_RETRANS_TIMEOUT;

	rpc_call_start(task);

}



static const struct rpc_call_ops rpc_null_ops = {

	.rpc_call_prepare = rpc_null_call_prepare,

	.rpc_call_done = rpc_default_callback,

};



static

struct rpc_task *rpc_call_null_helper(struct rpc_clnt *clnt,

		struct rpc_xprt *xprt, struct rpc_cred *cred, int flags,
@@ -2707,7 +2719,7 @@ struct rpc_task *rpc_call_null_helper(struct rpc_clnt *clnt, 
		.rpc_xprt = xprt,

		.rpc_message = &msg,

		.rpc_op_cred = cred,

		.callback_ops = (ops != NULL) ? ops : &rpc_default_ops,

		.callback_ops = ops ?: &rpc_null_ops,

		.callback_data = data,

		.flags = flags | RPC_TASK_SOFT | RPC_TASK_SOFTCONN |

			 RPC_TASK_NULLCREDS,
@@ -2758,6 +2770,7 @@ static void rpc_cb_add_xprt_release(void *calldata) 
}



static const struct rpc_call_ops rpc_cb_add_xprt_call_ops = {

	.rpc_call_prepare = rpc_null_call_prepare,

	.rpc_call_done = rpc_cb_add_xprt_done,

	.rpc_release = rpc_cb_add_xprt_release,

};