[PATCH 22/50] mars: add new file drivers/block/mars/xio_bricks/xio_net.c

[Thomas Schoebel-Theuer]

Signed-off-by: Thomas Schoebel-Theuer <tst@xxxxxxxxxxxxxxxxxx>
---
 drivers/block/mars/xio_bricks/xio_net.c | 1445 +++++++++++++++++++++++++++++++
 1 file changed, 1445 insertions(+)
 create mode 100644 drivers/block/mars/xio_bricks/xio_net.c

diff --git a/drivers/block/mars/xio_bricks/xio_net.c b/drivers/block/mars/xio_bricks/xio_net.c
new file mode 100644
index 0000000..4e31a78
--- /dev/null
+++ b/drivers/block/mars/xio_bricks/xio_net.c
@@ -0,0 +1,1445 @@
+/*  (c) 2011 Thomas Schoebel-Theuer / 1&1 Internet AG */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/moduleparam.h>
+
+#include <linux/xio.h>
+#include <linux/xio_net.h>
+
+#define USE_BUFFERING
+
+#define SEND_PROTO_VERSION		1
+
+/******************************************************************/
+
+/* Internal data structures for low-level transfer of C structures
+ * described by struct meta.
+ * Only these low-level fields need to have a fixed size like s64.
+ * The size and bytesex of the higher-level C structures is converted
+ * automatically; therefore classical "int" or "long long" etc is viable.
+ */
+
+#define MAX_FIELD_LEN			(32 + 16)
+
+struct xio_desc_cache {
+	u64   cache_sender_cookie;
+	u64   cache_recver_cookie;
+	u16   cache_sender_proto;
+	u16   cache_recver_proto;
+	s16   cache_items;
+	s8    cache_is_bigendian;
+	s8    cache_spare1;
+	s32   cache_spare2;
+	s32   cache_spare3;
+	u64   cache_spare4[4];
+};
+
+struct xio_desc_item {
+	char  field_name[MAX_FIELD_LEN];
+
+	s8    field_type;
+	s8    field_spare0;
+	s16   field_data_size;
+	s16   field_sender_size;
+	s16   field_sender_offset;
+	s16   field_recver_size;
+	s16   field_recver_offset;
+	s32   field_spare;
+};
+
+/* This must not be mirror symmetric between big and little endian
+ */
+#define XIO_DESC_MAGIC			0x73D0A2EC6148F48Ell
+
+struct xio_desc_header {
+	u64 h_magic;
+	u64 h_cookie;
+	s16 h_meta_len;
+	s16 h_index;
+	u32 h_spare1;
+	u64 h_spare2;
+};
+
+#define MAX_INT_TRANSFER		16
+
+/******************************************************************/
+
+/* Bytesex conversion / sign extension
+ */
+
+#ifdef __LITTLE_ENDIAN
+static const bool myself_is_bigendian;
+
+#endif
+#ifdef __BIG_ENDIAN
+static const bool myself_is_bigendian = true;
+
+#endif
+
+static inline
+void swap_bytes(void *data, int len)
+{
+	char *a = data;
+	char *b = data + len - 1;
+
+	while (a < b) {
+		char tmp = *a;
+
+		*a = *b;
+		*b = tmp;
+		a++;
+		b--;
+	}
+}
+
+#define SWAP_FIELD(x) swap_bytes(&(x), sizeof(x))
+
+static inline
+void swap_mc(struct xio_desc_cache *mc, int len)
+{
+	struct xio_desc_item *mi;
+
+	SWAP_FIELD(mc->cache_sender_cookie);
+	SWAP_FIELD(mc->cache_recver_cookie);
+	SWAP_FIELD(mc->cache_items);
+
+	len -= sizeof(*mc);
+
+	for (mi = (void *)(mc + 1); len > 0; mi++, len -= sizeof(*mi)) {
+		SWAP_FIELD(mi->field_type);
+		SWAP_FIELD(mi->field_data_size);
+		SWAP_FIELD(mi->field_sender_size);
+		SWAP_FIELD(mi->field_sender_offset);
+		SWAP_FIELD(mi->field_recver_size);
+		SWAP_FIELD(mi->field_recver_offset);
+	}
+}
+
+static inline
+char get_sign(const void *data, int len, bool is_bigendian, bool is_signed)
+{
+	if (is_signed) {
+		char x = is_bigendian ?
+			((const char *)data)[0] :
+			((const char *)data)[len - 1];
+		if (x < 0)
+			return -1;
+	}
+	return 0;
+}
+
+/******************************************************************/
+
+/* Low-level network traffic
+ */
+
+int xio_net_default_port = CONFIG_MARS_DEFAULT_PORT;
+EXPORT_SYMBOL_GPL(xio_net_default_port);
+module_param_named(xio_port, xio_net_default_port, int, 0);
+
+/* TODO: allow binding to specific source addresses instead of catch-all.
+ * TODO: make all the socket options configurable.
+ * TODO: implement signal handling.
+ * TODO: add authentication.
+ * TODO: add compression / encryption.
+ */
+
+struct xio_tcp_params default_tcp_params = {
+	.ip_tos = IPTOS_LOWDELAY,
+	.tcp_window_size = 8 * 1024 * 1024, /*	for long distance replications */
+	.tcp_nodelay = 0,
+	.tcp_timeout = 2,
+	.tcp_keepcnt = 3,
+	.tcp_keepintvl = 3, /*	keepalive ping time */
+	.tcp_keepidle = 4,
+};
+EXPORT_SYMBOL(default_tcp_params);
+
+static
+void __setsockopt(struct socket *sock, int level, int optname, char *optval, int optsize)
+{
+	int status = kernel_setsockopt(sock, level, optname, optval, optsize);
+
+	if (status < 0) {
+		XIO_WRN("cannot set %d socket option %d to value %d, status = %d\n",
+			 level, optname, *(int *)optval, status);
+	}
+}
+
+#define _setsockopt(sock, level, optname, val) __setsockopt(sock, level, optname, (char *)&(val), sizeof(val))
+
+int xio_create_sockaddr(struct sockaddr_storage *addr, const char *spec)
+{
+	struct sockaddr_in *sockaddr = (void *)addr;
+	const char *new_spec;
+	const char *tmp_spec;
+	int status = 0;
+
+	memset(addr, 0, sizeof(*addr));
+	sockaddr->sin_family = AF_INET;
+	sockaddr->sin_port = htons(xio_net_default_port);
+
+	/* Try to translate hostnames to IPs if possible.
+	 */
+	if (xio_translate_hostname)
+		new_spec = xio_translate_hostname(spec);
+	else
+		new_spec = brick_strdup(spec);
+	tmp_spec = new_spec;
+
+	/* This is PROVISIONARY!
+	 * TODO: add IPV6 syntax and many more features :)
+	 */
+	if (!*tmp_spec)
+		goto done;
+	if (*tmp_spec != ':') {
+		unsigned char u0 = 0, u1 = 0, u2 = 0, u3 = 0;
+
+		status = sscanf(tmp_spec, "%hhu.%hhu.%hhu.%hhu", &u0, &u1, &u2, &u3);
+		if (status != 4) {
+			XIO_ERR("invalid sockaddr IP syntax '%s', status = %d\n", tmp_spec, status);
+			status = -EINVAL;
+			goto done;
+		}
+		XIO_DBG("decoded IP = %u.%u.%u.%u\n", u0, u1, u2, u3);
+		sockaddr->sin_addr.s_addr = (__be32)u0 | (__be32)u1 << 8 | (__be32)u2 << 16 | (__be32)u3 << 24;
+	}
+	/*  deocde port number (when present) */
+	tmp_spec = spec;
+	while (*tmp_spec && *tmp_spec++ != ':')
+		/*empty*/;
+	if (*tmp_spec) {
+		int port = 0;
+
+		status = kstrtoint(tmp_spec, 0, &port);
+		if (unlikely(status)) {
+			XIO_ERR("invalid sockaddr PORT syntax '%s', status = %d\n", tmp_spec, status);
+			status = -EINVAL;
+			goto done;
+		}
+		XIO_DBG("decoded PORT = %d\n", port);
+		sockaddr->sin_port = htons(port);
+	}
+	status = 0;
+done:
+	brick_string_free(new_spec);
+	return status;
+}
+EXPORT_SYMBOL_GPL(xio_create_sockaddr);
+
+static int current_debug_nr; /*  no locking, just for debugging */
+
+static
+void _set_socketopts(struct socket *sock)
+{
+	struct timeval t = {
+		.tv_sec = default_tcp_params.tcp_timeout,
+	};
+	int x_true = 1;
+
+	/* TODO: improve this by a table-driven approach
+	 */
+	sock->sk->sk_rcvtimeo = sock->sk->sk_sndtimeo = default_tcp_params.tcp_timeout * HZ;
+	sock->sk->sk_reuse = 1;
+	_setsockopt(sock, SOL_SOCKET, SO_SNDBUFFORCE, default_tcp_params.tcp_window_size);
+	_setsockopt(sock, SOL_SOCKET, SO_RCVBUFFORCE, default_tcp_params.tcp_window_size);
+	_setsockopt(sock, SOL_IP, SO_PRIORITY, default_tcp_params.ip_tos);
+	_setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, default_tcp_params.tcp_nodelay);
+	_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, x_true);
+	_setsockopt(sock, IPPROTO_TCP, TCP_KEEPCNT, default_tcp_params.tcp_keepcnt);
+	_setsockopt(sock, IPPROTO_TCP, TCP_KEEPINTVL, default_tcp_params.tcp_keepintvl);
+	_setsockopt(sock, IPPROTO_TCP, TCP_KEEPIDLE, default_tcp_params.tcp_keepidle);
+	_setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, t);
+	_setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, t);
+
+	if (sock->file) { /*  switch back to blocking mode */
+		sock->file->f_flags &= ~O_NONBLOCK;
+	}
+}
+
+int xio_proto_exchange(struct xio_socket *msock, const char *msg)
+{
+	int status;
+
+	msock->s_send_proto = SEND_PROTO_VERSION;
+	status = xio_send_raw(msock, &msock->s_send_proto, 1, false);
+	if (unlikely(status < 0)) {
+		XIO_DBG("#%d protocol exchange on %s failed at sending, status = %d\n",
+			 msock->s_debug_nr,
+			 msg,
+			 status);
+		goto done;
+	}
+	status = xio_recv_raw(msock, &msock->s_recv_proto, 1, 1);
+	if (unlikely(status < 0)) {
+		XIO_DBG("#%d protocol exchange on %s failed at receiving, status = %d\n",
+			 msock->s_debug_nr,
+			 msg,
+			 status);
+		goto done;
+	}
+	/*  take the the minimum of both protocol versions */
+	if (msock->s_send_proto > msock->s_recv_proto)
+		msock->s_send_proto = msock->s_recv_proto;
+done:
+	return status;
+}
+
+int xio_create_socket(struct xio_socket *msock, struct sockaddr_storage *addr, bool is_server)
+{
+	struct socket *sock;
+	struct sockaddr *sockaddr = (void *)addr;
+	int status = -EEXIST;
+
+	if (unlikely(atomic_read(&msock->s_count))) {
+		XIO_ERR("#%d socket already in use\n", msock->s_debug_nr);
+		goto final;
+	}
+	if (unlikely(msock->s_socket)) {
+		XIO_ERR("#%d socket already open\n", msock->s_debug_nr);
+		goto final;
+	}
+	atomic_set(&msock->s_count, 1);
+
+	status = sock_create_kern(AF_INET, SOCK_STREAM, IPPROTO_TCP, &msock->s_socket);
+	if (unlikely(status < 0 || !msock->s_socket)) {
+		msock->s_socket = NULL;
+		XIO_WRN("cannot create socket, status = %d\n", status);
+		goto final;
+	}
+	msock->s_debug_nr = ++current_debug_nr;
+	sock = msock->s_socket;
+	CHECK_PTR(sock, done);
+	msock->s_alive = true;
+
+	_set_socketopts(sock);
+
+	if (is_server) {
+		status = kernel_bind(sock, sockaddr, sizeof(*sockaddr));
+		if (unlikely(status < 0)) {
+			XIO_WRN("#%d bind failed, status = %d\n", msock->s_debug_nr, status);
+			goto done;
+		}
+		status = kernel_listen(sock, 16);
+		if (status < 0)
+			XIO_WRN("#%d listen failed, status = %d\n", msock->s_debug_nr, status);
+	} else {
+		status = kernel_connect(sock, sockaddr, sizeof(*sockaddr), 0);
+		if (unlikely(status < 0)) {
+			XIO_DBG("#%d connect failed, status = %d\n", msock->s_debug_nr, status);
+			goto done;
+		}
+		status = xio_proto_exchange(msock, "connect");
+	}
+
+done:
+	if (status < 0)
+		xio_put_socket(msock);
+	else
+		XIO_DBG("successfully created socket #%d\n", msock->s_debug_nr);
+final:
+	return status;
+}
+EXPORT_SYMBOL_GPL(xio_create_socket);
+
+int xio_accept_socket(struct xio_socket *new_msock, struct xio_socket *old_msock)
+{
+	int status = -ENOENT;
+	struct socket *new_socket = NULL;
+	bool ok;
+
+	ok = xio_get_socket(old_msock);
+	if (likely(ok)) {
+		struct socket *sock = old_msock->s_socket;
+
+		if (unlikely(!sock))
+			goto err;
+
+		status = kernel_accept(sock, &new_socket, O_NONBLOCK);
+		if (unlikely(status < 0))
+			goto err;
+		if (unlikely(!new_socket)) {
+			status = -EBADF;
+			goto err;
+		}
+
+		_set_socketopts(new_socket);
+
+		memset(new_msock, 0, sizeof(struct xio_socket));
+		new_msock->s_socket = new_socket;
+		atomic_set(&new_msock->s_count, 1);
+		new_msock->s_alive = true;
+		new_msock->s_debug_nr = ++current_debug_nr;
+		XIO_DBG("#%d successfully accepted socket #%d\n", old_msock->s_debug_nr, new_msock->s_debug_nr);
+
+		status = xio_proto_exchange(new_msock, "accept");
+err:
+		xio_put_socket(old_msock);
+	}
+	return status;
+}
+EXPORT_SYMBOL_GPL(xio_accept_socket);
+
+bool xio_get_socket(struct xio_socket *msock)
+{
+	if (unlikely(atomic_read(&msock->s_count) <= 0)) {
+		XIO_ERR("#%d bad nesting on msock = %p\n", msock->s_debug_nr, msock);
+		return false;
+	}
+
+	atomic_inc(&msock->s_count);
+
+	if (unlikely(!msock->s_socket || !msock->s_alive)) {
+		xio_put_socket(msock);
+		return false;
+	}
+	return true;
+}
+EXPORT_SYMBOL_GPL(xio_get_socket);
+
+void xio_put_socket(struct xio_socket *msock)
+{
+	if (unlikely(atomic_read(&msock->s_count) <= 0)) {
+		XIO_ERR("#%d bad nesting on msock = %p sock = %p\n", msock->s_debug_nr, msock, msock->s_socket);
+	} else if (atomic_dec_and_test(&msock->s_count)) {
+		struct socket *sock = msock->s_socket;
+		int i;
+
+		XIO_DBG("#%d closing socket %p\n", msock->s_debug_nr, sock);
+		if (likely(sock && cmpxchg(&msock->s_alive, true, false)))
+			kernel_sock_shutdown(sock, SHUT_WR);
+		if (likely(sock && !msock->s_alive)) {
+			XIO_DBG("#%d releasing socket %p\n", msock->s_debug_nr, sock);
+			sock_release(sock);
+		}
+		for (i = 0; i < MAX_DESC_CACHE; i++) {
+			if (msock->s_desc_send[i])
+				brick_block_free(msock->s_desc_send[i], PAGE_SIZE);
+			if (msock->s_desc_recv[i])
+				brick_block_free(msock->s_desc_recv[i], PAGE_SIZE);
+		}
+		brick_block_free(msock->s_buffer, PAGE_SIZE);
+		memset(msock, 0, sizeof(struct xio_socket));
+	}
+}
+EXPORT_SYMBOL_GPL(xio_put_socket);
+
+void xio_shutdown_socket(struct xio_socket *msock)
+{
+	if (msock->s_socket) {
+		bool ok = xio_get_socket(msock);
+
+		if (likely(ok)) {
+			struct socket *sock = msock->s_socket;
+
+			if (likely(sock && cmpxchg(&msock->s_alive, true, false))) {
+				XIO_DBG("#%d shutdown socket %p\n", msock->s_debug_nr, sock);
+				kernel_sock_shutdown(sock, SHUT_WR);
+			}
+			xio_put_socket(msock);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(xio_shutdown_socket);
+
+bool xio_socket_is_alive(struct xio_socket *msock)
+{
+	bool res = false;
+
+	if (!msock->s_socket || !msock->s_alive)
+		goto done;
+	if (unlikely(atomic_read(&msock->s_count) <= 0)) {
+		XIO_ERR("#%d bad nesting on msock = %p sock = %p\n", msock->s_debug_nr, msock, msock->s_socket);
+		goto done;
+	}
+	res = true;
+done:
+	return res;
+}
+EXPORT_SYMBOL_GPL(xio_socket_is_alive);
+
+static
+int _xio_send_raw(struct xio_socket *msock, const void *buf, int len)
+{
+	int sleeptime = 1000 / HZ;
+	int sent = 0;
+	int status = 0;
+
+	msock->s_send_cnt = 0;
+	while (len > 0) {
+		int this_len = len;
+		struct socket *sock = msock->s_socket;
+
+		if (unlikely(!sock || !xio_net_is_alive || brick_thread_should_stop())) {
+			XIO_WRN("interrupting, sent = %d\n", sent);
+			status = -EIDRM;
+			break;
+		}
+
+		{
+			struct kvec iov = {
+				.iov_base = (void *)buf,
+				.iov_len = this_len,
+			};
+			struct msghdr msg = {
+				.msg_iov = (struct iovec *)&iov,
+				.msg_flags = 0 | MSG_NOSIGNAL,
+			};
+			status = kernel_sendmsg(sock, &msg, &iov, 1, this_len);
+		}
+
+		if (status == -EAGAIN) {
+			if (msock->s_send_abort > 0 && ++msock->s_send_cnt > msock->s_send_abort) {
+				XIO_WRN("#%d reached send abort %d\n", msock->s_debug_nr, msock->s_send_abort);
+				status = -EINTR;
+				break;
+			}
+			brick_msleep(sleeptime);
+			/*  linearly increasing backoff */
+			if (sleeptime < 100)
+				sleeptime += 1000 / HZ;
+			continue;
+		}
+		msock->s_send_cnt = 0;
+		if (unlikely(status == -EINTR)) { /*  ignore it */
+			flush_signals(current);
+			brick_msleep(50);
+			continue;
+		}
+		if (unlikely(!status)) {
+			XIO_WRN("#%d EOF from socket upon send_page()\n", msock->s_debug_nr);
+			brick_msleep(50);
+			status = -ECOMM;
+			break;
+		}
+		if (unlikely(status < 0)) {
+			XIO_WRN("#%d bad socket sendmsg, len=%d, this_len=%d, sent=%d, status = %d\n",
+				msock->s_debug_nr,
+				len,
+				this_len,
+				sent,
+				status);
+			break;
+		}
+
+		len -= status;
+		buf += status;
+		sent += status;
+		sleeptime = 1000 / HZ;
+	}
+
+	if (status >= 0)
+		status = sent;
+
+	return status;
+}
+
+int xio_send_raw(struct xio_socket *msock, const void *buf, int len, bool cork)
+{
+#ifdef USE_BUFFERING
+	int sent = 0;
+	int rest = len;
+
+#endif
+	int status = -EINVAL;
+
+	if (!xio_get_socket(msock))
+		goto final;
+
+#ifdef USE_BUFFERING
+restart:
+	if (!msock->s_buffer) {
+		msock->s_pos = 0;
+		msock->s_buffer = brick_block_alloc(0, PAGE_SIZE);
+	}
+
+	if (msock->s_pos + rest < PAGE_SIZE) {
+		memcpy(msock->s_buffer + msock->s_pos, buf, rest);
+		msock->s_pos += rest;
+		sent += rest;
+		rest = 0;
+		status = sent;
+		if (cork)
+			goto done;
+	}
+
+	if (msock->s_pos > 0) {
+		status = _xio_send_raw(msock, msock->s_buffer, msock->s_pos);
+		if (status < 0)
+			goto done;
+
+		brick_block_free(msock->s_buffer, PAGE_SIZE);
+		msock->s_buffer = NULL;
+		msock->s_pos = 0;
+	}
+
+	if (rest >= PAGE_SIZE) {
+		status = _xio_send_raw(msock, buf, rest);
+		goto done;
+	} else if (rest > 0) {
+		goto restart;
+	}
+	status = sent;
+
+done:
+#else
+	status = _xio_send_raw(msock, buf, len);
+#endif
+	if (status < 0 && msock->s_shutdown_on_err)
+		xio_shutdown_socket(msock);
+
+	xio_put_socket(msock);
+
+final:
+	return status;
+}
+EXPORT_SYMBOL_GPL(xio_send_raw);
+
+/* Note: buf may be NULL. In this case, the data is simply consumed,
+ * like /dev/null
+ */
+int xio_recv_raw(struct xio_socket *msock, void *buf, int minlen, int maxlen)
+{
+	void *dummy = NULL;
+	int sleeptime = 1000 / HZ;
+	int status = -EIDRM;
+	int done = 0;
+
+	if (!buf)
+		buf = dummy = brick_block_alloc(0, maxlen);
+
+	if (!xio_get_socket(msock))
+		goto final;
+
+	msock->s_recv_cnt = 0;
+
+	while (done < minlen) {
+		struct kvec iov = {
+			.iov_base = buf + done,
+			.iov_len = maxlen - done,
+		};
+		struct msghdr msg = {
+			.msg_iovlen = 1,
+			.msg_iov = (struct iovec *)&iov,
+			.msg_flags = MSG_NOSIGNAL,
+		};
+		struct socket *sock = msock->s_socket;
+
+		if (unlikely(!sock)) {
+			XIO_WRN("#%d socket has disappeared\n", msock->s_debug_nr);
+			status = -EIDRM;
+			goto err;
+		}
+
+		if (!xio_net_is_alive || brick_thread_should_stop()) {
+			XIO_WRN("#%d interrupting, done = %d\n", msock->s_debug_nr, done);
+			if (done > 0)
+				status = -EIDRM;
+			goto err;
+		}
+
+		status = kernel_recvmsg(sock, &msg, &iov, 1, maxlen-done, msg.msg_flags);
+
+		if (!xio_net_is_alive || brick_thread_should_stop()) {
+			XIO_WRN("#%d interrupting, done = %d\n", msock->s_debug_nr, done);
+			if (done > 0)
+				status = -EIDRM;
+			goto err;
+		}
+
+		if (status == -EAGAIN) {
+			if (msock->s_recv_abort > 0 && ++msock->s_recv_cnt > msock->s_recv_abort) {
+				XIO_WRN("#%d reached recv abort %d\n", msock->s_debug_nr, msock->s_recv_abort);
+				status = -EINTR;
+				goto err;
+			}
+			brick_msleep(sleeptime);
+			/*  linearly increasing backoff */
+			if (sleeptime < 100)
+				sleeptime += 1000 / HZ;
+			continue;
+		}
+		msock->s_recv_cnt = 0;
+		if (!status) { /*  EOF */
+			XIO_WRN("#%d got EOF from socket (done=%d, req_size=%d)\n",
+				msock->s_debug_nr,
+				done,
+				maxlen - done);
+			status = -EPIPE;
+			goto err;
+		}
+		if (status < 0) {
+			XIO_WRN("#%d bad recvmsg, status = %d\n", msock->s_debug_nr, status);
+			goto err;
+		}
+		done += status;
+		sleeptime = 1000 / HZ;
+	}
+	status = done;
+
+err:
+	if (status < 0 && msock->s_shutdown_on_err)
+		xio_shutdown_socket(msock);
+	xio_put_socket(msock);
+final:
+	if (dummy)
+		brick_block_free(dummy, maxlen);
+	return status;
+}
+EXPORT_SYMBOL_GPL(xio_recv_raw);
+
+/*********************************************************************/
+
+/* Mid-level field data exchange
+ */
+
+static
+int _add_fields(struct xio_desc_item *mi, const struct meta *meta, int offset, const char *prefix, int maxlen)
+{
+	int count = 0;
+
+	for (; meta->field_name != NULL; meta++) {
+		const char *new_prefix;
+		int new_offset;
+		int len;
+
+		short this_size;
+
+		new_prefix = mi->field_name;
+		new_offset = offset + meta->field_offset;
+
+		if (unlikely(maxlen < sizeof(struct xio_desc_item))) {
+			XIO_ERR("desc cache item overflow\n");
+			count = -1;
+			goto done;
+		}
+
+		len = scnprintf(mi->field_name, MAX_FIELD_LEN, "%s.%s", prefix, meta->field_name);
+		if (unlikely(len >= MAX_FIELD_LEN)) {
+			XIO_ERR("field len overflow on '%s.%s'\n", prefix, meta->field_name);
+			count = -1;
+			goto done;
+		}
+		mi->field_type = meta->field_type;
+		this_size = meta->field_data_size;
+		mi->field_data_size = this_size;
+		mi->field_sender_size = this_size;
+		this_size = meta->field_transfer_size;
+		if (this_size > 0)
+			mi->field_sender_size = this_size;
+		mi->field_sender_offset = new_offset;
+		mi->field_recver_offset = -1;
+
+		mi++;
+		maxlen -= sizeof(struct xio_desc_item);
+		count++;
+
+		if (meta->field_type == FIELD_SUB) {
+			int sub_count;
+
+			sub_count = _add_fields(mi, meta->field_ref, new_offset, new_prefix, maxlen);
+			if (sub_count < 0)
+				return sub_count;
+
+			mi += sub_count;
+			count += sub_count;
+			maxlen -= sub_count * sizeof(struct xio_desc_item);
+		}
+	}
+done:
+	return count;
+}
+
+static
+struct xio_desc_cache *make_sender_cache(struct xio_socket *msock, const struct meta *meta, int *cache_index)
+{
+	int orig_len = PAGE_SIZE;
+	int maxlen = orig_len;
+	struct xio_desc_cache *mc;
+	struct xio_desc_item *mi;
+	int i;
+	int status;
+
+	for (i = 0; i < MAX_DESC_CACHE; i++) {
+		mc = msock->s_desc_send[i];
+		if (!mc)
+			break;
+		if (mc->cache_sender_cookie == (u64)meta)
+			goto done;
+	}
+
+	if (unlikely(i >= MAX_DESC_CACHE - 1)) {
+		XIO_ERR("#%d desc cache overflow\n", msock->s_debug_nr);
+		return NULL;
+	}
+
+	mc = brick_block_alloc(0, maxlen);
+
+	memset(mc, 0, maxlen);
+	mc->cache_sender_cookie = (u64)meta;
+	/*  further bits may be used in future */
+	mc->cache_sender_proto = msock->s_send_proto;
+	mc->cache_recver_proto = msock->s_recv_proto;
+
+	maxlen -= sizeof(struct xio_desc_cache);
+	mi = (void *)(mc + 1);
+
+	status = _add_fields(mi, meta, 0, "", maxlen);
+
+	if (likely(status > 0)) {
+		mc->cache_items = status;
+		mc->cache_is_bigendian = myself_is_bigendian;
+		msock->s_desc_send[i] = mc;
+		*cache_index = i;
+	} else {
+		brick_block_free(mc, orig_len);
+		mc = NULL;
+	}
+
+done:
+	return mc;
+}
+
+static
+void _make_recver_cache(struct xio_desc_cache *mc, const struct meta *meta, int offset, const char *prefix)
+{
+	char *tmp = brick_string_alloc(MAX_FIELD_LEN);
+	int i;
+
+	for (; meta->field_name != NULL; meta++) {
+		snprintf(tmp, MAX_FIELD_LEN, "%s.%s", prefix, meta->field_name);
+		for (i = 0; i < mc->cache_items; i++) {
+			struct xio_desc_item *mi = ((struct xio_desc_item *)(mc + 1)) + i;
+
+			if (meta->field_type == mi->field_type &&
+			    !strcmp(tmp, mi->field_name)) {
+				mi->field_recver_size = meta->field_data_size;
+				mi->field_recver_offset = offset + meta->field_offset;
+				if (meta->field_type == FIELD_SUB)
+					_make_recver_cache(mc, meta->field_ref, mi->field_recver_offset, tmp);
+				goto found;
+			}
+		}
+		XIO_WRN("field '%s' is missing\n", meta->field_name);
+found:;
+	}
+	brick_string_free(tmp);
+}
+
+static
+void make_recver_cache(struct xio_desc_cache *mc, const struct meta *meta)
+{
+	int i;
+
+	_make_recver_cache(mc, meta, 0, "");
+
+	for (i = 0; i < mc->cache_items; i++) {
+		struct xio_desc_item *mi = ((struct xio_desc_item *)(mc + 1)) + i;
+
+		if (unlikely(mi->field_recver_offset < 0))
+			XIO_WRN("field '%s' is not transferred\n", mi->field_name);
+	}
+}
+
+#define _CHECK_STATUS(_txt_)						\
+do {									\
+	if (unlikely(status < 0)) {					\
+		XIO_DBG("%s status = %d\n", _txt_, status);		\
+		goto err;						\
+	}								\
+} while (0)
+
+static
+int _desc_send_item(struct xio_socket *msock,
+	const void *data,
+	const struct xio_desc_cache *mc,
+	int index,
+	bool cork)
+{
+	struct xio_desc_item *mi = ((struct xio_desc_item *)(mc + 1)) + index;
+	const void *item = data + mi->field_sender_offset;
+
+	s16 data_len = mi->field_data_size;
+	s16 transfer_len = mi->field_sender_size;
+	int status;
+	bool is_signed = false;
+	int res = -1;
+
+	switch (mi->field_type) {
+	case FIELD_REF:
+		XIO_ERR("field '%s' NYI type = %d\n", mi->field_name, mi->field_type);
+		goto err;
+	case FIELD_SUB:
+		/* skip this */
+		res = 0;
+		break;
+	case FIELD_INT:
+		is_signed = true;
+		/* fallthrough */
+	case FIELD_UINT:
+		if (unlikely(data_len <= 0 || data_len > MAX_INT_TRANSFER)) {
+			XIO_ERR("field '%s' bad data_len = %d\n", mi->field_name, data_len);
+			goto err;
+		}
+		if (unlikely(transfer_len > MAX_INT_TRANSFER)) {
+			XIO_ERR("field '%s' bad transfer_len = %d\n", mi->field_name, transfer_len);
+			goto err;
+		}
+
+		if (likely(data_len == transfer_len))
+			goto raw;
+
+		if (transfer_len > data_len) {
+			int diff = transfer_len - data_len;
+			char empty[diff];
+			char sign;
+
+			sign = get_sign(item, data_len, myself_is_bigendian, is_signed);
+			memset(empty, sign, diff);
+
+			if (myself_is_bigendian) {
+				status = xio_send_raw(msock, empty, diff, true);
+				_CHECK_STATUS("send_diff");
+				status = xio_send_raw(msock, item, data_len, cork);
+				_CHECK_STATUS("send_item");
+
+			} else {
+				status = xio_send_raw(msock, item, data_len, true);
+				_CHECK_STATUS("send_item");
+				status = xio_send_raw(msock, empty, diff, cork);
+				_CHECK_STATUS("send_diff");
+			}
+
+			res = data_len;
+			break;
+		} else if (unlikely(transfer_len <= 0)) {
+			XIO_ERR("bad transfer_len = %d\n", transfer_len);
+			goto err;
+		} else { /*  transfer_len < data_len */
+			char check = get_sign(item, data_len, myself_is_bigendian, is_signed);
+			int start;
+			int end;
+			int i;
+
+			if (is_signed &&
+			    unlikely(get_sign(item, transfer_len, myself_is_bigendian, true) != check)) {
+				XIO_ERR("cannot sign-reduce signed integer from %d to %d bytes, byte %d !~ %d\n",
+					 data_len,
+					 transfer_len,
+					 ((char *)item)[transfer_len - 1],
+					 check);
+				goto err;
+			}
+
+			if (myself_is_bigendian) {
+				start = 0;
+				end = data_len - transfer_len;
+			} else {
+				start = transfer_len;
+				end = data_len;
+			}
+
+			for (i = start; i < end; i++) {
+				if (unlikely(((char *)item)[i] != check)) {
+					XIO_ERR("cannot sign-reduce %ssigned integer from %d to %d bytes at pos %d, byte %d != %d\n",
+						 is_signed ? "" : "un",
+						 data_len,
+						 transfer_len,
+						 i,
+						 ((char *)item)[i],
+						 check);
+					goto err;
+				}
+			}
+
+			/*  just omit the higher/lower bytes */
+			data_len = transfer_len;
+			if (myself_is_bigendian)
+				item += end;
+			goto raw;
+		}
+	case FIELD_STRING:
+		item = *(void **)item;
+		data_len = 0;
+		if (item)
+			data_len = strlen(item) + 1;
+
+		status = xio_send_raw(msock, &data_len, sizeof(data_len), true);
+		_CHECK_STATUS("send_string_len");
+		/* fallthrough */
+	case FIELD_RAW:
+raw:
+		if (unlikely(data_len < 0)) {
+			XIO_ERR("field '%s' bad data_len = %d\n", mi->field_name, data_len);
+			goto err;
+		}
+		status = xio_send_raw(msock, item, data_len, cork);
+		_CHECK_STATUS("send_raw");
+		res = data_len;
+		break;
+	default:
+		XIO_ERR("field '%s' unknown type = %d\n", mi->field_name, mi->field_type);
+	}
+err:
+	return res;
+}
+
+static
+int _desc_recv_item(struct xio_socket *msock, void *data, const struct xio_desc_cache *mc, int index, int line)
+{
+	struct xio_desc_item *mi = ((struct xio_desc_item *)(mc + 1)) + index;
+	void *item = NULL;
+
+	s16 data_len = mi->field_recver_size;
+	s16 transfer_len = mi->field_sender_size;
+	int status;
+	bool is_signed = false;
+	int res = -1;
+
+	if (likely(data && data_len > 0 && mi->field_recver_offset >= 0))
+		item = data + mi->field_recver_offset;
+
+	switch (mi->field_type) {
+	case FIELD_REF:
+		XIO_ERR("field '%s' NYI type = %d\n", mi->field_name, mi->field_type);
+		goto err;
+	case FIELD_SUB:
+		/* skip this */
+		res = 0;
+		break;
+	case FIELD_INT:
+		is_signed = true;
+		/* fallthrough */
+	case FIELD_UINT:
+		if (unlikely(data_len <= 0 || data_len > MAX_INT_TRANSFER)) {
+			XIO_ERR("field '%s' bad data_len = %d\n", mi->field_name, data_len);
+			goto err;
+		}
+		if (unlikely(transfer_len > MAX_INT_TRANSFER)) {
+			XIO_ERR("field '%s' bad transfer_len = %d\n", mi->field_name, transfer_len);
+			goto err;
+		}
+
+		if (likely(data_len == transfer_len))
+			goto raw;
+
+		if (transfer_len > data_len) {
+			int diff = transfer_len - data_len;
+			char empty[diff];
+			char check;
+
+			memset(empty, 0, diff);
+
+			if (myself_is_bigendian) {
+				status = xio_recv_raw(msock, empty, diff, diff);
+				_CHECK_STATUS("recv_diff");
+			}
+
+			status = xio_recv_raw(msock, item, data_len, data_len);
+			_CHECK_STATUS("recv_item");
+			if (unlikely(mc->cache_is_bigendian != myself_is_bigendian && item))
+				swap_bytes(item, data_len);
+
+			if (!myself_is_bigendian) {
+				status = xio_recv_raw(msock, empty, diff, diff);
+				_CHECK_STATUS("recv_diff");
+			}
+
+			/*  check that sign extension did no harm */
+			check = get_sign(empty, diff, mc->cache_is_bigendian, is_signed);
+			while (--diff >= 0) {
+				if (unlikely(empty[diff] != check)) {
+					XIO_ERR("field '%s' %sSIGNED INTEGER OVERFLOW on size reduction from %d to %d, byte %d != %d\n",
+						 mi->field_name,
+						 is_signed ? "" : "UN",
+						 transfer_len,
+						 data_len,
+						 empty[diff],
+						 check);
+					goto err;
+				}
+			}
+			if (is_signed && item &&
+			    unlikely(get_sign(item, data_len, myself_is_bigendian, true) != check)) {
+				XIO_ERR("field '%s' SIGNED INTEGER OVERLOW on reduction from size %d to %d, byte %d !~ %d\n",
+					 mi->field_name,
+					 transfer_len,
+					 data_len,
+					 ((char *)item)[data_len - 1],
+					 check);
+				goto err;
+			}
+
+			res = data_len;
+			break;
+		} else if (unlikely(transfer_len <= 0)) {
+			XIO_ERR("field '%s' bad transfer_len = %d\n", mi->field_name, transfer_len);
+			goto err;
+		} else if (unlikely(!item)) { /*  shortcut without checks */
+			data_len = transfer_len;
+			goto raw;
+		} else { /*  transfer_len < data_len */
+			int diff = data_len - transfer_len;
+			char *transfer_ptr = item;
+			char sign;
+
+			if (myself_is_bigendian)
+				transfer_ptr += diff;
+
+			status = xio_recv_raw(msock, transfer_ptr, transfer_len, transfer_len);
+			_CHECK_STATUS("recv_transfer");
+			if (unlikely(mc->cache_is_bigendian != myself_is_bigendian))
+				swap_bytes(transfer_ptr, transfer_len);
+
+			/*  sign-extend from transfer_len to data_len */
+			sign = get_sign(transfer_ptr, transfer_len, myself_is_bigendian, is_signed);
+			if (myself_is_bigendian)
+				memset(item, sign, diff);
+			else
+				memset(item + transfer_len, sign, diff);
+			res = data_len;
+			break;
+		}
+	case FIELD_STRING:
+		data_len = 0;
+		status = xio_recv_raw(msock, &data_len, sizeof(data_len), sizeof(data_len));
+		_CHECK_STATUS("recv_string_len");
+
+		if (unlikely(mc->cache_is_bigendian != myself_is_bigendian))
+			swap_bytes(&data_len, sizeof(data_len));
+
+		if (data_len > 0 && item) {
+			char *str = _brick_string_alloc(data_len, line);
+
+			*(void **)item = str;
+			item = str;
+		}
+
+		transfer_len = data_len;
+		/* fallthrough */
+	case FIELD_RAW:
+raw:
+		if (unlikely(data_len < 0)) {
+			XIO_ERR("field = '%s' implausible data_len = %d\n", mi->field_name, data_len);
+			goto err;
+		}
+		if (likely(data_len > 0)) {
+			if (unlikely(transfer_len != data_len)) {
+				XIO_ERR("cannot handle generic mismatch in transfer sizes, field = '%s', %d != %d\n",
+					mi->field_name,
+					transfer_len,
+					data_len);
+				goto err;
+			}
+			status = xio_recv_raw(msock, item, data_len, data_len);
+			_CHECK_STATUS("recv_raw");
+		}
+		res = data_len;
+		break;
+	default:
+		XIO_ERR("field '%s' unknown type = %d\n", mi->field_name, mi->field_type);
+	}
+err:
+	return res;
+}
+
+static inline
+int _desc_send_struct(struct xio_socket *msock, int cache_index, const void *data, int h_meta_len, bool cork)
+{
+	const struct xio_desc_cache *mc = msock->s_desc_send[cache_index];
+
+	struct xio_desc_header header = {
+		.h_magic = XIO_DESC_MAGIC,
+		.h_cookie = mc->cache_sender_cookie,
+		.h_meta_len = h_meta_len,
+		.h_index = data ? cache_index : -1,
+	};
+	int index;
+	int count = 0;
+	int status = 0;
+
+	status = xio_send_raw(msock, &header, sizeof(header), cork || data);
+	_CHECK_STATUS("send_header");
+
+	if (unlikely(h_meta_len > 0)) {
+		status = xio_send_raw(msock, mc, h_meta_len, true);
+		_CHECK_STATUS("send_meta");
+	}
+
+	if (likely(data)) {
+		for (index = 0; index < mc->cache_items; index++) {
+			status = _desc_send_item(msock, data, mc, index, cork || index < mc->cache_items-1);
+			_CHECK_STATUS("send_cache_item");
+			count++;
+		}
+	}
+
+	if (status >= 0)
+		status = count;
+err:
+	return status;
+}
+
+static
+int desc_send_struct(struct xio_socket *msock, const void *data, const struct meta *meta, bool cork)
+{
+	struct xio_desc_cache *mc;
+	int i;
+	int h_meta_len = 0;
+	int status = -EINVAL;
+
+	for (i = 0; i < MAX_DESC_CACHE; i++) {
+		mc = msock->s_desc_send[i];
+		if (!mc)
+			break;
+		if (mc->cache_sender_cookie == (u64)meta)
+			goto found;
+	}
+
+	mc = make_sender_cache(msock, meta, &i);
+	if (unlikely(!mc))
+		goto done;
+
+	h_meta_len = mc->cache_items * sizeof(struct xio_desc_item) + sizeof(struct xio_desc_cache);
+
+found:
+	status = _desc_send_struct(msock, i, data, h_meta_len, cork);
+
+done:
+	return status;
+}
+
+static
+int desc_recv_struct(struct xio_socket *msock, void *data, const struct meta *meta, int line)
+{
+	struct xio_desc_header header = {};
+	struct xio_desc_cache *mc;
+	int cache_index;
+	int index;
+	int count = 0;
+	int status = 0;
+	bool need_swap = false;
+
+	status = xio_recv_raw(msock, &header, sizeof(header), sizeof(header));
+	_CHECK_STATUS("recv_header");
+
+	if (unlikely(header.h_magic != XIO_DESC_MAGIC)) {
+		need_swap = true;
+		SWAP_FIELD(header.h_magic);
+		if (unlikely(header.h_magic != XIO_DESC_MAGIC)) {
+			XIO_WRN("#%d called from line %d bad packet header magic = %llx\n",
+				msock->s_debug_nr,
+				line,
+				header.h_magic);
+			status = -ENOMSG;
+			goto err;
+		}
+		SWAP_FIELD(header.h_cookie);
+		SWAP_FIELD(header.h_meta_len);
+		SWAP_FIELD(header.h_index);
+	}
+
+	cache_index = header.h_index;
+	if (cache_index < 0) { /*  EOR */
+		goto done;
+	}
+	if (unlikely(cache_index >= MAX_DESC_CACHE - 1)) {
+		XIO_WRN("#%d called from line %d bad cache index %d\n", msock->s_debug_nr, line, cache_index);
+		status = -EBADF;
+		goto err;
+	}
+
+	mc = msock->s_desc_recv[cache_index];
+	if (unlikely(!mc)) {
+		if (unlikely(header.h_meta_len <= 0)) {
+			XIO_WRN("#%d called from line %d missing meta information\n", msock->s_debug_nr, line);
+			status = -ENOMSG;
+			goto err;
+		}
+
+		mc = _brick_block_alloc(0, PAGE_SIZE, line);
+
+		status = xio_recv_raw(msock, mc, header.h_meta_len, header.h_meta_len);
+		if (unlikely(status < 0))
+			brick_block_free(mc, PAGE_SIZE);
+		_CHECK_STATUS("recv_meta");
+
+		if (unlikely(need_swap))
+			swap_mc(mc, header.h_meta_len);
+
+		make_recver_cache(mc, meta);
+
+		msock->s_desc_recv[cache_index] = mc;
+	} else if (unlikely(header.h_meta_len > 0)) {
+		XIO_WRN("#%d called from line %d has %d unexpected meta bytes\n",
+			msock->s_debug_nr,
+			line,
+			header.h_meta_len);
+	}
+
+	for (index = 0; index < mc->cache_items; index++) {
+		status = _desc_recv_item(msock, data, mc, index, line);
+		_CHECK_STATUS("recv_cache_item");
+		count++;
+	}
+
+done:
+	if (status >= 0)
+		status = count;
+err:
+	return status;
+}
+
+int xio_send_struct(struct xio_socket *msock, const void *data, const struct meta *meta)
+{
+	return desc_send_struct(msock, data, meta, false);
+}
+EXPORT_SYMBOL_GPL(xio_send_struct);
+
+int _xio_recv_struct(struct xio_socket *msock, void *data, const struct meta *meta, int line)
+{
+	return desc_recv_struct(msock, data, meta, line);
+}
+EXPORT_SYMBOL_GPL(_xio_recv_struct);
+
+/*********************************************************************/
+
+/* High-level transport of xio structures
+ */
+
+const struct meta xio_cmd_meta[] = {
+	META_INI_SUB(cmd_stamp, struct xio_cmd, xio_timespec_meta),
+	META_INI(cmd_code, struct xio_cmd, FIELD_INT),
+	META_INI(cmd_int1, struct xio_cmd, FIELD_INT),
+	META_INI(cmd_str1, struct xio_cmd, FIELD_STRING),
+	{}
+};
+EXPORT_SYMBOL_GPL(xio_cmd_meta);
+
+int xio_send_aio(struct xio_socket *msock, struct aio_object *aio)
+{
+	struct xio_cmd cmd = {
+		.cmd_code = CMD_AIO,
+		.cmd_int1 = aio->io_id,
+	};
+	int seq = 0;
+	int status;
+
+	if (aio->io_rw != 0 && aio->io_data && aio->io_cs_mode < 2)
+		cmd.cmd_code |= CMD_FLAG_HAS_DATA;
+
+	get_lamport(&cmd.cmd_stamp);
+
+	status = desc_send_struct(msock, &cmd, xio_cmd_meta, true);
+	if (status < 0)
+		goto done;
+
+	seq = 0;
+	status = desc_send_struct(msock, aio, xio_aio_meta, cmd.cmd_code & CMD_FLAG_HAS_DATA);
+	if (status < 0)
+		goto done;
+
+	if (cmd.cmd_code & CMD_FLAG_HAS_DATA)
+		status = xio_send_raw(msock, aio->io_data, aio->io_len, false);
+done:
+	return status;
+}
+EXPORT_SYMBOL_GPL(xio_send_aio);
+
+int xio_recv_aio(struct xio_socket *msock, struct aio_object *aio, struct xio_cmd *cmd)
+{
+	int status;
+
+	status = desc_recv_struct(msock, aio, xio_aio_meta, __LINE__);
+	if (status < 0)
+		goto done;
+
+	set_lamport(&cmd->cmd_stamp);
+
+	if (cmd->cmd_code & CMD_FLAG_HAS_DATA) {
+		if (!aio->io_data)
+			aio->io_data = brick_zmem_alloc(aio->io_len);
+		status = xio_recv_raw(msock, aio->io_data, aio->io_len, aio->io_len);
+		if (status < 0)
+			XIO_WRN("#%d aio_len = %d, status = %d\n", msock->s_debug_nr, aio->io_len, status);
+	}
+done:
+	return status;
+}
+EXPORT_SYMBOL_GPL(xio_recv_aio);
+
+int xio_send_cb(struct xio_socket *msock, struct aio_object *aio)
+{
+	struct xio_cmd cmd = {
+		.cmd_code = CMD_CB,
+		.cmd_int1 = aio->io_id,
+	};
+	int seq = 0;
+	int status;
+
+	if (aio->io_rw == 0 && aio->io_data && aio->io_cs_mode < 2)
+		cmd.cmd_code |= CMD_FLAG_HAS_DATA;
+
+	get_lamport(&cmd.cmd_stamp);
+
+	status = desc_send_struct(msock, &cmd, xio_cmd_meta, true);
+	if (status < 0)
+		goto done;
+
+	seq = 0;
+	status = desc_send_struct(msock, aio, xio_aio_meta, cmd.cmd_code & CMD_FLAG_HAS_DATA);
+	if (status < 0)
+		goto done;
+
+	if (cmd.cmd_code & CMD_FLAG_HAS_DATA)
+		status = xio_send_raw(msock, aio->io_data, aio->io_len, false);
+done:
+	return status;
+}
+EXPORT_SYMBOL_GPL(xio_send_cb);
+
+int xio_recv_cb(struct xio_socket *msock, struct aio_object *aio, struct xio_cmd *cmd)
+{
+	int status;
+
+	status = desc_recv_struct(msock, aio, xio_aio_meta, __LINE__);
+	if (status < 0)
+		goto done;
+
+	set_lamport(&cmd->cmd_stamp);
+
+	if (cmd->cmd_code & CMD_FLAG_HAS_DATA) {
+		if (!aio->io_data) {
+			XIO_WRN("#%d no internal buffer available\n", msock->s_debug_nr);
+			status = -EINVAL;
+			goto done;
+		}
+		status = xio_recv_raw(msock, aio->io_data, aio->io_len, aio->io_len);
+	}
+done:
+	return status;
+}
+EXPORT_SYMBOL_GPL(xio_recv_cb);
+
+/***************** module init stuff ************************/
+
+char *(*xio_translate_hostname)(const char *name) = NULL;
+EXPORT_SYMBOL_GPL(xio_translate_hostname);
+
+bool xio_net_is_alive = false;
+EXPORT_SYMBOL_GPL(xio_net_is_alive);
+
+int __init init_xio_net(void)
+{
+	XIO_INF("init_net()\n");
+	xio_net_is_alive = true;
+	return 0;
+}
+
+void exit_xio_net(void)
+{
+	xio_net_is_alive = false;
+	XIO_INF("exit_net()\n");
+}
-- 
2.0.0

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