Commit a5cda73e authored by Chuck Lever's avatar Chuck Lever
Browse files

SUNRPC: Restructure svc_tcp_recv_record() 



Refactor: svc_recvfrom() is going to be converted to read into
bio_vecs in a moment. Unhook the only other caller,
svc_tcp_recv_record(), which just wants to read the 4-byte stream
record marker into a kvec.

While we're in the area, streamline this helper by straight-lining
the hot path, replace dprintk call sites with tracepoints, and
reduce the number of atomic bit operations in this path.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 02648908

include/trace/events/sunrpc.h

+24 −0
Original line number Diff line number Diff line
@@ -1443,6 +1443,30 @@ TRACE_EVENT(svcsock_new_socket, 
	)

);



TRACE_EVENT(svcsock_marker,

	TP_PROTO(

		const struct svc_xprt *xprt,

		__be32 marker

	),



	TP_ARGS(xprt, marker),



	TP_STRUCT__entry(

		__field(unsigned int, length)

		__field(bool, last)

		__string(addr, xprt->xpt_remotebuf)

	),



	TP_fast_assign(

		__entry->length = be32_to_cpu(marker) & RPC_FRAGMENT_SIZE_MASK;

		__entry->last = be32_to_cpu(marker) & RPC_LAST_STREAM_FRAGMENT;

		__assign_str(addr, xprt->xpt_remotebuf);

	),



	TP_printk("addr=%s length=%u%s", __get_str(addr),

		__entry->length, __entry->last ? " (last)" : "")

);



DECLARE_EVENT_CLASS(svcsock_class,

	TP_PROTO(

		const struct svc_xprt *xprt,

net/sunrpc/svcsock.c

+25 −26
Original line number Diff line number Diff line
@@ -828,47 +828,45 @@ static void svc_tcp_clear_pages(struct svc_sock *svsk) 
}



/*

 * Receive fragment record header.

 * If we haven't gotten the record length yet, get the next four bytes.

 * Receive fragment record header into sk_marker.

 */

static int svc_tcp_recv_record(struct svc_sock *svsk, struct svc_rqst *rqstp)

static ssize_t svc_tcp_read_marker(struct svc_sock *svsk,

				   struct svc_rqst *rqstp)

{

	struct svc_serv	*serv = svsk->sk_xprt.xpt_server;

	unsigned int want;

	int len;

	ssize_t want, len;



	/* If we haven't gotten the record length yet,

	 * get the next four bytes.

	 */

	if (svsk->sk_tcplen < sizeof(rpc_fraghdr)) {

		struct msghdr	msg = { NULL };

		struct kvec	iov;



		want = sizeof(rpc_fraghdr) - svsk->sk_tcplen;

		iov.iov_base = ((char *)&svsk->sk_marker) + svsk->sk_tcplen;

		iov.iov_len  = want;

		len = svc_recvfrom(rqstp, &iov, 1, want, 0);

		iov_iter_kvec(&msg.msg_iter, READ, &iov, 1, want);

		len = sock_recvmsg(svsk->sk_sock, &msg, MSG_DONTWAIT);

		if (len < 0)

			goto error;

			return len;

		svsk->sk_tcplen += len;



		if (len < want) {

			dprintk("svc: short recvfrom while reading record "

				"length (%d of %d)\n", len, want);

			return -EAGAIN;

			/* call again to read the remaining bytes */

			goto err_short;

		}



		dprintk("svc: TCP record, %d bytes\n", svc_sock_reclen(svsk));

		trace_svcsock_marker(&svsk->sk_xprt, svsk->sk_marker);

		if (svc_sock_reclen(svsk) + svsk->sk_datalen >

							serv->sv_max_mesg) {

			net_notice_ratelimited("RPC: fragment too large: %d\n",

					svc_sock_reclen(svsk));

			goto err_delete;

		}

		    svsk->sk_xprt.xpt_server->sv_max_mesg)

			goto err_too_large;

	}



	return svc_sock_reclen(svsk);

error:

	dprintk("RPC: TCP recv_record got %d\n", len);

	return len;

err_delete:



err_too_large:

	net_notice_ratelimited("svc: %s %s RPC fragment too large: %d\n",

			       __func__, svsk->sk_xprt.xpt_server->sv_name,

			       svc_sock_reclen(svsk));

	set_bit(XPT_CLOSE, &svsk->sk_xprt.xpt_flags);

err_short:

	return -EAGAIN;

}
@@ -961,12 +959,13 @@ static int svc_tcp_recvfrom(struct svc_rqst *rqstp) 
		test_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags),

		test_bit(XPT_CLOSE, &svsk->sk_xprt.xpt_flags));



	len = svc_tcp_recv_record(svsk, rqstp);

	clear_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);

	len = svc_tcp_read_marker(svsk, rqstp);

	if (len < 0)

		goto error;



	base = svc_tcp_restore_pages(svsk, rqstp);

	want = svc_sock_reclen(svsk) - (svsk->sk_tcplen - sizeof(rpc_fraghdr));

	want = len - (svsk->sk_tcplen - sizeof(rpc_fraghdr));



	vec = rqstp->rq_vec;