[PATCH v6 15/22] net/failsafe: add plug-in support

[Gaetan Rivet <gaetan.rivet@6wind.com>]

Periodically check for the existence of a device.
If a device has not been initialized and exists on the system, then it
is probed and configured.

The configuration process strives to synchronize the states between the
plugged-in sub-device and the fail-safe device.

Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>
Acked-by: Olga Shern <olgas@mellanox.com>
---
 doc/guides/nics/fail_safe.rst           |  19 +++
 drivers/net/failsafe/Makefile           |   1 +
 drivers/net/failsafe/failsafe.c         |  71 ++++++++++
 drivers/net/failsafe/failsafe_args.c    |  32 +++++
 drivers/net/failsafe/failsafe_eal.c     |  30 +----
 drivers/net/failsafe/failsafe_ether.c   | 228 ++++++++++++++++++++++++++++++++
 drivers/net/failsafe/failsafe_ops.c     |  25 ++--
 drivers/net/failsafe/failsafe_private.h |  60 ++++++++-
 8 files changed, 423 insertions(+), 43 deletions(-)
 create mode 100644 drivers/net/failsafe/failsafe_ether.c

diff --git a/doc/guides/nics/fail_safe.rst b/doc/guides/nics/fail_safe.rst
index 056f85f..c04891a 100644
--- a/doc/guides/nics/fail_safe.rst
+++ b/doc/guides/nics/fail_safe.rst
@@ -102,6 +102,11 @@ Fail-safe command line parameters
   address is generated, that will be subsequently applied to all sub-device once
   they are probed.
 
+- **hotplug_poll** parameter [UINT64] (default **2000**)
+
+  This parameter allows the user to configure the amount of time in milliseconds
+  between two slave upkeep round.
+
 Usage example
 ~~~~~~~~~~~~~
 
@@ -131,3 +136,17 @@ Care must be taken, however, to respect the **ether** API concerning device
 access, and in particular, using the ``RTE_ETH_FOREACH_DEV`` macro to iterate
 over ethernet devices, instead of directly accessing them or by writing one's
 own device iterator.
+
+Plug-in feature
+---------------
+
+A sub-device can be defined without existing on the system when the fail-safe
+PMD is initialized. Upon probing this device, the fail-safe PMD will detect its
+absence and postpone its use. It will then register for a periodic check on any
+missing sub-device.
+
+During this time, the fail-safe PMD can be used normally, configured and told to
+emit and receive packets. It will store any applied configuration, and try to
+apply it upon the probing of its missing sub-device. After this configuration
+pass, the new sub-device will be synchronized with other sub-devices, i.e. be
+started if the fail-safe PMD has been started by the user before.
diff --git a/drivers/net/failsafe/Makefile b/drivers/net/failsafe/Makefile
index c759035..e27bfc0 100644
--- a/drivers/net/failsafe/Makefile
+++ b/drivers/net/failsafe/Makefile
@@ -44,6 +44,7 @@ SRCS-$(CONFIG_RTE_LIBRTE_PMD_FAILSAFE) += failsafe_args.c
 SRCS-$(CONFIG_RTE_LIBRTE_PMD_FAILSAFE) += failsafe_eal.c
 SRCS-$(CONFIG_RTE_LIBRTE_PMD_FAILSAFE) += failsafe_ops.c
 SRCS-$(CONFIG_RTE_LIBRTE_PMD_FAILSAFE) += failsafe_rxtx.c
+SRCS-$(CONFIG_RTE_LIBRTE_PMD_FAILSAFE) += failsafe_ether.c
 
 # No exported include files
 
diff --git a/drivers/net/failsafe/failsafe.c b/drivers/net/failsafe/failsafe.c
index 7cf33e8..888f07b 100644
--- a/drivers/net/failsafe/failsafe.c
+++ b/drivers/net/failsafe/failsafe.c
@@ -80,6 +80,72 @@ fs_sub_device_free(struct rte_eth_dev *dev)
 	rte_free(PRIV(dev)->subs);
 }
 
+static void fs_hotplug_alarm(void *arg);
+
+int
+failsafe_hotplug_alarm_install(struct rte_eth_dev *dev)
+{
+	int ret;
+
+	if (dev == NULL)
+		return -EINVAL;
+	if (PRIV(dev)->pending_alarm)
+		return 0;
+	ret = rte_eal_alarm_set(hotplug_poll * 1000,
+				fs_hotplug_alarm,
+				dev);
+	if (ret) {
+		ERROR("Could not set up plug-in event detection");
+		return ret;
+	}
+	PRIV(dev)->pending_alarm = 1;
+	return 0;
+}
+
+int
+failsafe_hotplug_alarm_cancel(struct rte_eth_dev *dev)
+{
+	int ret = 0;
+
+	if (PRIV(dev)->pending_alarm) {
+		rte_errno = 0;
+		rte_eal_alarm_cancel(fs_hotplug_alarm, dev);
+		if (rte_errno) {
+			ERROR("rte_eal_alarm_cancel failed (errno: %s)",
+			      strerror(rte_errno));
+			ret = -rte_errno;
+		} else {
+			PRIV(dev)->pending_alarm = 0;
+		}
+	}
+	return ret;
+}
+
+static void
+fs_hotplug_alarm(void *arg)
+{
+	struct rte_eth_dev *dev = arg;
+	struct sub_device *sdev;
+	int ret;
+	uint8_t i;
+
+	if (!PRIV(dev)->pending_alarm)
+		return;
+	PRIV(dev)->pending_alarm = 0;
+	FOREACH_SUBDEV(sdev, i, dev)
+		if (sdev->state != PRIV(dev)->state)
+			break;
+	/* if we have non-probed device */
+	if (i != PRIV(dev)->subs_tail) {
+		ret = failsafe_eth_dev_state_sync(dev);
+		if (ret)
+			ERROR("Unable to synchronize sub_device state");
+	}
+	ret = failsafe_hotplug_alarm_install(dev);
+	if (ret)
+		ERROR("Unable to set up next alarm");
+}
+
 static int
 fs_eth_dev_create(struct rte_vdev_device *vdev)
 {
@@ -128,6 +194,11 @@ fs_eth_dev_create(struct rte_vdev_device *vdev)
 	ret = failsafe_eal_init(dev);
 	if (ret)
 		goto free_args;
+	ret = failsafe_hotplug_alarm_install(dev);
+	if (ret) {
+		ERROR("Could not set up plug-in event detection");
+		goto free_args;
+	}
 	mac = &dev->data->mac_addrs[0];
 	if (mac_from_arg) {
 		/*
diff --git a/drivers/net/failsafe/failsafe_args.c b/drivers/net/failsafe/failsafe_args.c
index f07d26e..8f334aa 100644
--- a/drivers/net/failsafe/failsafe_args.c
+++ b/drivers/net/failsafe/failsafe_args.c
@@ -45,9 +45,11 @@
 typedef int (parse_cb)(struct rte_eth_dev *dev, const char *params,
 		uint8_t head);
 
+uint64_t hotplug_poll;
 int mac_from_arg;
 
 const char *pmd_failsafe_init_parameters[] = {
+	PMD_FAILSAFE_PLUG_IN_POLL_KVARG,
 	PMD_FAILSAFE_MAC_KVARG,
 	NULL,
 };
@@ -221,6 +223,24 @@ fs_remove_sub_devices_definition(char params[DEVARGS_MAXLEN])
 }
 
 static int
+fs_get_u64_arg(const char *key __rte_unused,
+		const char *value, void *out)
+{
+	uint64_t *u64 = out;
+	char *endptr = NULL;
+
+	if ((value == NULL) || (out == NULL))
+		return -EINVAL;
+	errno = 0;
+	*u64 = strtoull(value, &endptr, 0);
+	if (errno != 0)
+		return -errno;
+	if (endptr == value)
+		return -1;
+	return 0;
+}
+
+static int
 fs_get_mac_addr_arg(const char *key __rte_unused,
 		const char *value, void *out)
 {
@@ -252,6 +272,7 @@ failsafe_args_parse(struct rte_eth_dev *dev, const char *params)
 	ret = 0;
 	priv->subs_tx = FAILSAFE_MAX_ETHPORTS;
 	/* default parameters */
+	hotplug_poll = FAILSAFE_HOTPLUG_DEFAULT_TIMEOUT_MS;
 	mac_from_arg = 0;
 	n = snprintf(mut_params, sizeof(mut_params), "%s", params);
 	if (n >= sizeof(mut_params)) {
@@ -274,6 +295,16 @@ failsafe_args_parse(struct rte_eth_dev *dev, const char *params)
 				PMD_FAILSAFE_PARAM_STRING);
 			return -1;
 		}
+		/* PLUG_IN event poll timer */
+		arg_count = rte_kvargs_count(kvlist,
+				PMD_FAILSAFE_PLUG_IN_POLL_KVARG);
+		if (arg_count == 1) {
+			ret = rte_kvargs_process(kvlist,
+					PMD_FAILSAFE_PLUG_IN_POLL_KVARG,
+					&fs_get_u64_arg, &hotplug_poll);
+			if (ret < 0)
+				goto free_kvlist;
+		}
 		/* MAC addr */
 		arg_count = rte_kvargs_count(kvlist,
 				PMD_FAILSAFE_MAC_KVARG);
@@ -287,6 +318,7 @@ failsafe_args_parse(struct rte_eth_dev *dev, const char *params)
 			mac_from_arg = 1;
 		}
 	}
+	PRIV(dev)->state = DEV_PARSED;
 free_kvlist:
 	rte_kvargs_free(kvlist);
 	return ret;
diff --git a/drivers/net/failsafe/failsafe_eal.c b/drivers/net/failsafe/failsafe_eal.c
index 6c3a811..16871df 100644
--- a/drivers/net/failsafe/failsafe_eal.c
+++ b/drivers/net/failsafe/failsafe_eal.c
@@ -88,37 +88,14 @@ fs_bus_init(struct rte_eth_dev *dev)
 int
 failsafe_eal_init(struct rte_eth_dev *dev)
 {
-	struct sub_device *sdev;
-	uint8_t i;
 	int ret;
 
 	ret = fs_bus_init(dev);
 	if (ret)
 		return ret;
-	/*
-	 * We only update TX_SUBDEV if we are not started.
-	 * If a sub_device is emitting, we will switch the TX_SUBDEV to the
-	 * preferred port only upon starting it, so that the switch is smoother.
-	 */
-	if (PREFERRED_SUBDEV(dev)->state >= DEV_PROBED) {
-		if (TX_SUBDEV(dev) != PREFERRED_SUBDEV(dev) &&
-		    (TX_SUBDEV(dev) == NULL ||
-		     (TX_SUBDEV(dev) && TX_SUBDEV(dev)->state < DEV_STARTED))) {
-			DEBUG("Switching tx_dev to preferred sub_device");
-			PRIV(dev)->subs_tx = 0;
-		}
-	} else {
-		if ((TX_SUBDEV(dev) && TX_SUBDEV(dev)->state < DEV_PROBED) ||
-		    TX_SUBDEV(dev) == NULL) {
-			/* Using first probed device */
-			FOREACH_SUBDEV_ST(sdev, i, dev, DEV_PROBED) {
-				DEBUG("Switching tx_dev to sub_device %d",
-				      i);
-				PRIV(dev)->subs_tx = i;
-				break;
-			}
-		}
-	}
+	if (PRIV(dev)->state < DEV_PROBED)
+		PRIV(dev)->state = DEV_PROBED;
+	fs_switch_dev(dev);
 	return 0;
 }
 
@@ -150,5 +127,6 @@ failsafe_eal_uninit(struct rte_eth_dev *dev)
 	ret = fs_bus_uninit(dev);
 	if (ret)
 		return ret;
+	PRIV(dev)->state = DEV_PROBED - 1;
 	return 0;
 }
diff --git a/drivers/net/failsafe/failsafe_ether.c b/drivers/net/failsafe/failsafe_ether.c
new file mode 100644
index 0000000..7910952
--- /dev/null
+++ b/drivers/net/failsafe/failsafe_ether.c
@@ -0,0 +1,228 @@
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright 2017 6WIND S.A.
+ *   Copyright 2017 Mellanox.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of 6WIND S.A. nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <unistd.h>
+
+#include "failsafe_private.h"
+
+static int
+fs_eth_dev_conf_apply(struct rte_eth_dev *dev,
+		struct sub_device *sdev)
+{
+	struct rte_eth_dev *edev;
+	struct rte_vlan_filter_conf *vfc1;
+	struct rte_vlan_filter_conf *vfc2;
+	uint32_t i;
+	int ret;
+
+	edev = ETH(sdev);
+	/* RX queue setup */
+	for (i = 0; i < dev->data->nb_rx_queues; i++) {
+		struct rxq *rxq;
+
+		rxq = dev->data->rx_queues[i];
+		ret = rte_eth_rx_queue_setup(PORT_ID(sdev), i,
+				rxq->info.nb_desc, rxq->socket_id,
+				&rxq->info.conf, rxq->info.mp);
+		if (ret) {
+			ERROR("rx_queue_setup failed");
+			return ret;
+		}
+	}
+	/* TX queue setup */
+	for (i = 0; i < dev->data->nb_tx_queues; i++) {
+		struct txq *txq;
+
+		txq = dev->data->tx_queues[i];
+		ret = rte_eth_tx_queue_setup(PORT_ID(sdev), i,
+				txq->info.nb_desc, txq->socket_id,
+				&txq->info.conf);
+		if (ret) {
+			ERROR("tx_queue_setup failed");
+			return ret;
+		}
+	}
+	/* dev_link.link_status */
+	if (dev->data->dev_link.link_status !=
+	    edev->data->dev_link.link_status) {
+		DEBUG("Configuring link_status");
+		if (dev->data->dev_link.link_status)
+			ret = rte_eth_dev_set_link_up(PORT_ID(sdev));
+		else
+			ret = rte_eth_dev_set_link_down(PORT_ID(sdev));
+		if (ret) {
+			ERROR("Failed to apply link_status");
+			return ret;
+		}
+	} else {
+		DEBUG("link_status already set");
+	}
+	/* promiscuous */
+	if (dev->data->promiscuous != edev->data->promiscuous) {
+		DEBUG("Configuring promiscuous");
+		if (dev->data->promiscuous)
+			rte_eth_promiscuous_enable(PORT_ID(sdev));
+		else
+			rte_eth_promiscuous_disable(PORT_ID(sdev));
+	} else {
+		DEBUG("promiscuous already set");
+	}
+	/* all_multicast */
+	if (dev->data->all_multicast != edev->data->all_multicast) {
+		DEBUG("Configuring all_multicast");
+		if (dev->data->all_multicast)
+			rte_eth_allmulticast_enable(PORT_ID(sdev));
+		else
+			rte_eth_allmulticast_disable(PORT_ID(sdev));
+	} else {
+		DEBUG("all_multicast already set");
+	}
+	/* MTU */
+	if (dev->data->mtu != edev->data->mtu) {
+		DEBUG("Configuring MTU");
+		ret = rte_eth_dev_set_mtu(PORT_ID(sdev), dev->data->mtu);
+		if (ret) {
+			ERROR("Failed to apply MTU");
+			return ret;
+		}
+	} else {
+		DEBUG("MTU already set");
+	}
+	/* default MAC */
+	DEBUG("Configuring default MAC address");
+	ret = rte_eth_dev_default_mac_addr_set(PORT_ID(sdev),
+			&dev->data->mac_addrs[0]);
+	if (ret) {
+		ERROR("Setting default MAC address failed");
+		return ret;
+	}
+	/* additional MAC */
+	if (PRIV(dev)->nb_mac_addr > 1)
+		DEBUG("Configure additional MAC address%s",
+			(PRIV(dev)->nb_mac_addr > 2 ? "es" : ""));
+	for (i = 1; i < PRIV(dev)->nb_mac_addr; i++) {
+		struct ether_addr *ea;
+
+		ea = &dev->data->mac_addrs[i];
+		ret = rte_eth_dev_mac_addr_add(PORT_ID(sdev), ea,
+				PRIV(dev)->mac_addr_pool[i]);
+		if (ret) {
+			char ea_fmt[ETHER_ADDR_FMT_SIZE];
+
+			ether_format_addr(ea_fmt, ETHER_ADDR_FMT_SIZE, ea);
+			ERROR("Adding MAC address %s failed", ea_fmt);
+		}
+	}
+	/* VLAN filter */
+	vfc1 = &dev->data->vlan_filter_conf;
+	vfc2 = &edev->data->vlan_filter_conf;
+	if (memcmp(vfc1, vfc2, sizeof(struct rte_vlan_filter_conf))) {
+		uint64_t vbit;
+		uint64_t ids;
+		size_t i;
+		uint16_t vlan_id;
+
+		DEBUG("Configuring VLAN filter");
+		for (i = 0; i < RTE_DIM(vfc1->ids); i++) {
+			if (vfc1->ids[i] == 0)
+				continue;
+			ids = vfc1->ids[i];
+			while (ids) {
+				vlan_id = 64 * i;
+				/* count trailing zeroes */
+				vbit = ~ids & (ids - 1);
+				/* clear least significant bit set */
+				ids ^= (ids ^ (ids - 1)) ^ vbit;
+				for (; vbit; vlan_id++)
+					vbit >>= 1;
+				ret = rte_eth_dev_vlan_filter(
+					PORT_ID(sdev), vlan_id, 1);
+				if (ret) {
+					ERROR("Failed to apply VLAN filter %hu",
+						vlan_id);
+					return ret;
+				}
+			}
+		}
+	} else {
+		DEBUG("VLAN filter already set");
+	}
+	return 0;
+}
+
+int
+failsafe_eth_dev_state_sync(struct rte_eth_dev *dev)
+{
+	struct sub_device *sdev;
+	uint32_t inactive;
+	int ret;
+	uint8_t i;
+
+	if (PRIV(dev)->state < DEV_PROBED)
+		return 0;
+	ret = failsafe_eal_init(dev);
+	if (ret)
+		return ret;
+	if (PRIV(dev)->state < DEV_ACTIVE)
+		return 0;
+	inactive = 0;
+	FOREACH_SUBDEV(sdev, i, dev)
+		if (sdev->state == DEV_PROBED)
+			inactive |= UINT32_C(1) << i;
+	ret = dev->dev_ops->dev_configure(dev);
+	if (ret)
+		return ret;
+	FOREACH_SUBDEV(sdev, i, dev) {
+		if (inactive & (UINT32_C(1) << i)) {
+			ret = fs_eth_dev_conf_apply(dev, sdev);
+			if (ret) {
+				ERROR("Could not apply configuration to sub_device %d",
+				      i);
+				/* TODO: disable device */
+				return ret;
+			}
+		}
+	}
+	/*
+	 * If new devices have been configured, check if
+	 * the link state has changed.
+	 */
+	if (inactive)
+		dev->dev_ops->link_update(dev, 1);
+	if (PRIV(dev)->state < DEV_STARTED)
+		return 0;
+	ret = dev->dev_ops->dev_start(dev);
+	if (ret)
+		return ret;
+	return 0;
+}
diff --git a/drivers/net/failsafe/failsafe_ops.c b/drivers/net/failsafe/failsafe_ops.c
index 693162e..4044473 100644
--- a/drivers/net/failsafe/failsafe_ops.c
+++ b/drivers/net/failsafe/failsafe_ops.c
@@ -89,6 +89,8 @@ fs_dev_configure(struct rte_eth_dev *dev)
 		}
 		sdev->state = DEV_ACTIVE;
 	}
+	if (PRIV(dev)->state < DEV_ACTIVE)
+		PRIV(dev)->state = DEV_ACTIVE;
 	return 0;
 }
 
@@ -108,21 +110,9 @@ fs_dev_start(struct rte_eth_dev *dev)
 			return ret;
 		sdev->state = DEV_STARTED;
 	}
-	if (PREFERRED_SUBDEV(dev)->state == DEV_STARTED) {
-		if (TX_SUBDEV(dev) != PREFERRED_SUBDEV(dev)) {
-			DEBUG("Switching tx_dev to preferred sub_device");
-			PRIV(dev)->subs_tx = 0;
-		}
-	} else {
-		if ((TX_SUBDEV(dev) && TX_SUBDEV(dev)->state < DEV_STARTED) ||
-		    TX_SUBDEV(dev) == NULL) {
-			FOREACH_SUBDEV_ST(sdev, i, dev, DEV_STARTED) {
-				DEBUG("Switching tx_dev to sub_device %d", i);
-				PRIV(dev)->subs_tx = i;
-				break;
-			}
-		}
-	}
+	if (PRIV(dev)->state < DEV_STARTED)
+		PRIV(dev)->state = DEV_STARTED;
+	fs_switch_dev(dev);
 	return 0;
 }
 
@@ -132,6 +122,7 @@ fs_dev_stop(struct rte_eth_dev *dev)
 	struct sub_device *sdev;
 	uint8_t i;
 
+	PRIV(dev)->state = DEV_STARTED - 1;
 	FOREACH_SUBDEV_ST(sdev, i, dev, DEV_STARTED) {
 		rte_eth_dev_stop(PORT_ID(sdev));
 		sdev->state = DEV_STARTED - 1;
@@ -183,6 +174,10 @@ fs_dev_close(struct rte_eth_dev *dev)
 	struct sub_device *sdev;
 	uint8_t i;
 
+	failsafe_hotplug_alarm_cancel(dev);
+	if (PRIV(dev)->state == DEV_STARTED)
+		dev->dev_ops->dev_stop(dev);
+	PRIV(dev)->state = DEV_ACTIVE - 1;
 	FOREACH_SUBDEV_ST(sdev, i, dev, DEV_ACTIVE) {
 		DEBUG("Closing sub_device %d", i);
 		rte_eth_dev_close(PORT_ID(sdev));
diff --git a/drivers/net/failsafe/failsafe_private.h b/drivers/net/failsafe/failsafe_private.h
index e7a7592..8fb72fe 100644
--- a/drivers/net/failsafe/failsafe_private.h
+++ b/drivers/net/failsafe/failsafe_private.h
@@ -41,12 +41,14 @@
 #define FAILSAFE_DRIVER_NAME "Fail-safe PMD"
 
 #define PMD_FAILSAFE_MAC_KVARG "mac"
+#define PMD_FAILSAFE_PLUG_IN_POLL_KVARG "hotplug_poll"
 #define PMD_FAILSAFE_PARAM_STRING	\
 	"dev(<ifc>),"			\
-	"mac=mac_addr"			\
+	"mac=mac_addr,"			\
+	"hotplug_poll=u64"		\
 	""
 
-#define FAILSAFE_PLUGIN_DEFAULT_TIMEOUT_MS 2000
+#define FAILSAFE_HOTPLUG_DEFAULT_TIMEOUT_MS 2000
 
 #define FAILSAFE_MAX_ETHPORTS 2
 #define FAILSAFE_MAX_ETHADDR 128
@@ -105,8 +107,22 @@ struct fs_priv {
 	uint32_t mac_addr_pool[FAILSAFE_MAX_ETHADDR];
 	/* current capabilities */
 	struct rte_eth_dev_info infos;
+	/*
+	 * Fail-safe state machine.
+	 * This level will be tracking state of the EAL and eth
+	 * layer at large as defined by the user application.
+	 * It will then steer the sub_devices toward the same
+	 * synchronized state.
+	 */
+	enum dev_state state;
+	unsigned int pending_alarm:1; /* An alarm is pending */
 };
 
+/* MISC */
+
+int failsafe_hotplug_alarm_install(struct rte_eth_dev *dev);
+int failsafe_hotplug_alarm_cancel(struct rte_eth_dev *dev);
+
 /* RX / TX */
 
 uint16_t failsafe_rx_burst(void *rxq,
@@ -125,10 +141,15 @@ int failsafe_args_count_subdevice(struct rte_eth_dev *dev, const char *params);
 int failsafe_eal_init(struct rte_eth_dev *dev);
 int failsafe_eal_uninit(struct rte_eth_dev *dev);
 
+/* ETH_DEV */
+
+int failsafe_eth_dev_state_sync(struct rte_eth_dev *dev);
+
 /* GLOBALS */
 
 extern const char pmd_failsafe_driver_name[];
 extern const struct eth_dev_ops failsafe_ops;
+extern uint64_t hotplug_poll;
 extern int mac_from_arg;
 
 /* HELPERS */
@@ -224,4 +245,39 @@ fs_find_next(struct rte_eth_dev *dev, uint8_t sid,
 	return sid;
 }
 
+static inline void
+fs_switch_dev(struct rte_eth_dev *dev)
+{
+	enum dev_state req_state;
+
+	req_state = PRIV(dev)->state;
+	if (PREFERRED_SUBDEV(dev)->state >= req_state) {
+		if (TX_SUBDEV(dev) != PREFERRED_SUBDEV(dev) &&
+		    (TX_SUBDEV(dev) == NULL ||
+		     (req_state == DEV_STARTED) ||
+		     (TX_SUBDEV(dev) && TX_SUBDEV(dev)->state < DEV_STARTED))) {
+			DEBUG("Switching tx_dev to preferred sub_device");
+			PRIV(dev)->subs_tx = 0;
+		}
+	} else if ((TX_SUBDEV(dev) && TX_SUBDEV(dev)->state < req_state) ||
+		   TX_SUBDEV(dev) == NULL) {
+		struct sub_device *sdev;
+		uint8_t i;
+
+		/* Using acceptable device */
+		FOREACH_SUBDEV_ST(sdev, i, dev, req_state) {
+			DEBUG("Switching tx_dev to sub_device %d",
+			      i);
+			PRIV(dev)->subs_tx = i;
+			break;
+		}
+	} else if (TX_SUBDEV(dev) && TX_SUBDEV(dev)->state < req_state) {
+		DEBUG("No device ready, deactivating tx_dev");
+		PRIV(dev)->subs_tx = PRIV(dev)->subs_tail;
+	} else {
+		return;
+	}
+	rte_wmb();
+}
+
 #endif /* _RTE_ETH_FAILSAFE_PRIVATE_H_ */
-- 
2.1.4