SUNRPC: Trim stack utilization in the wrap and unwrap paths

By preventing compiler inlining of the integrity and privacy
helpers, stack utilization for the common case (authentication only)
goes way down.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

net/sunrpc/auth_gss/auth_gss.c

@@ -1724,8 +1724,9 @@ gss_validate(struct rpc_task *task, struct xdr_stream *xdr)
 	goto out;
 }
 
-static int gss_wrap_req_integ(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
-			      struct rpc_task *task, struct xdr_stream *xdr)
+static noinline_for_stack int
+gss_wrap_req_integ(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
+		   struct rpc_task *task, struct xdr_stream *xdr)
 {
 	struct rpc_rqst *rqstp = task->tk_rqstp;
 	struct xdr_buf integ_buf, *snd_buf = &rqstp->rq_snd_buf;
@@ -1816,8 +1817,9 @@ alloc_enc_pages(struct rpc_rqst *rqstp)
 	return -EAGAIN;
 }
 
-static int gss_wrap_req_priv(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
-			     struct rpc_task *task, struct xdr_stream *xdr)
+static noinline_for_stack int
+gss_wrap_req_priv(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
+		  struct rpc_task *task, struct xdr_stream *xdr)
 {
 	struct rpc_rqst *rqstp = task->tk_rqstp;
 	struct xdr_buf	*snd_buf = &rqstp->rq_snd_buf;
@@ -1947,7 +1949,7 @@ gss_unwrap_resp_auth(struct rpc_cred *cred)
  *		proc_req_arg_t arg;
  *	};
  */
-static int
+static noinline_for_stack int
 gss_unwrap_resp_integ(struct rpc_task *task, struct rpc_cred *cred,
 		      struct gss_cl_ctx *ctx, struct rpc_rqst *rqstp,
 		      struct xdr_stream *xdr)
@@ -2021,7 +2023,7 @@ gss_unwrap_resp_integ(struct rpc_task *task, struct rpc_cred *cred,
 	goto out;
 }
 
-static int
+static noinline_for_stack int
 gss_unwrap_resp_priv(struct rpc_task *task, struct rpc_cred *cred,
 		     struct gss_cl_ctx *ctx, struct rpc_rqst *rqstp,
 		     struct xdr_stream *xdr)