eal/linux: add uevent parse and process

In order to handle the uevent which has been detected from the kernel
side, add uevent parse and process function to translate the uevent into
device event, which user has subscribed to monitor.

Signed-off-by: Jeff Guo <jia.guo@intel.com>
Reviewed-by: Jianfeng Tan <jianfeng.tan@intel.com>

doc/guides/rel_notes/release_18_05.rst

@@ -68,6 +68,8 @@ New Features
   * ``rte_dev_event_callback_register`` and ``rte_dev_event_callback_unregister``
     are for the user's callbacks register and unregister.
 
+  Linux uevent is supported as backend of this device event notification framework.
+
 
 API Changes
 -----------

lib/librte_eal/linuxapp/eal/eal_dev.c

@@ -2,21 +2,222 @@
  * Copyright(c) 2018 Intel Corporation
  */
 
+#include <string.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <linux/netlink.h>
+
 #include <rte_log.h>
 #include <rte_compat.h>
 #include <rte_dev.h>
+#include <rte_malloc.h>
+#include <rte_interrupts.h>
+#include <rte_alarm.h>
+
+#include "eal_private.h"
+
+static struct rte_intr_handle intr_handle = {.fd = -1 };
+static bool monitor_started;
+
+#define EAL_UEV_MSG_LEN 4096
+#define EAL_UEV_MSG_ELEM_LEN 128
+
+static void dev_uev_handler(__rte_unused void *param);
+
+/* identify the system layer which reports this event. */
+enum eal_dev_event_subsystem {
+	EAL_DEV_EVENT_SUBSYSTEM_PCI, /* PCI bus device event */
+	EAL_DEV_EVENT_SUBSYSTEM_UIO, /* UIO driver device event */
+	EAL_DEV_EVENT_SUBSYSTEM_VFIO, /* VFIO driver device event */
+	EAL_DEV_EVENT_SUBSYSTEM_MAX
+};
+
+static int
+dev_uev_socket_fd_create(void)
+{
+	struct sockaddr_nl addr;
+	int ret;
+
+	intr_handle.fd = socket(PF_NETLINK, SOCK_RAW | SOCK_CLOEXEC |
+			SOCK_NONBLOCK,
+			NETLINK_KOBJECT_UEVENT);
+	if (intr_handle.fd < 0) {
+		RTE_LOG(ERR, EAL, "create uevent fd failed.\n");
+		return -1;
+	}
+
+	memset(&addr, 0, sizeof(addr));
+	addr.nl_family = AF_NETLINK;
+	addr.nl_pid = 0;
+	addr.nl_groups = 0xffffffff;
+
+	ret = bind(intr_handle.fd, (struct sockaddr *) &addr, sizeof(addr));
+	if (ret < 0) {
+		RTE_LOG(ERR, EAL, "Failed to bind uevent socket.\n");
+		goto err;
+	}
 
+	return 0;
+err:
+	close(intr_handle.fd);
+	intr_handle.fd = -1;
+	return ret;
+}
+
+static int
+dev_uev_parse(const char *buf, struct rte_dev_event *event, int length)
+{
+	char action[EAL_UEV_MSG_ELEM_LEN];
+	char subsystem[EAL_UEV_MSG_ELEM_LEN];
+	char pci_slot_name[EAL_UEV_MSG_ELEM_LEN];
+	int i = 0;
+
+	memset(action, 0, EAL_UEV_MSG_ELEM_LEN);
+	memset(subsystem, 0, EAL_UEV_MSG_ELEM_LEN);
+	memset(pci_slot_name, 0, EAL_UEV_MSG_ELEM_LEN);
+
+	while (i < length) {
+		for (; i < length; i++) {
+			if (*buf)
+				break;
+			buf++;
+		}
+		/**
+		 * check device uevent from kernel side, no need to check
+		 * uevent from udev.
+		 */
+		if (!strncmp(buf, "libudev", 7)) {
+			buf += 7;
+			i += 7;
+			return -1;
+		}
+		if (!strncmp(buf, "ACTION=", 7)) {
+			buf += 7;
+			i += 7;
+			snprintf(action, sizeof(action), "%s", buf);
+		} else if (!strncmp(buf, "SUBSYSTEM=", 10)) {
+			buf += 10;
+			i += 10;
+			snprintf(subsystem, sizeof(subsystem), "%s", buf);
+		} else if (!strncmp(buf, "PCI_SLOT_NAME=", 14)) {
+			buf += 14;
+			i += 14;
+			snprintf(pci_slot_name, sizeof(subsystem), "%s", buf);
+			event->devname = strdup(pci_slot_name);
+		}
+		for (; i < length; i++) {
+			if (*buf == '\0')
+				break;
+			buf++;
+		}
+	}
+
+	/* parse the subsystem layer */
+	if (!strncmp(subsystem, "uio", 3))
+		event->subsystem = EAL_DEV_EVENT_SUBSYSTEM_UIO;
+	else if (!strncmp(subsystem, "pci", 3))
+		event->subsystem = EAL_DEV_EVENT_SUBSYSTEM_PCI;
+	else if (!strncmp(subsystem, "vfio", 4))
+		event->subsystem = EAL_DEV_EVENT_SUBSYSTEM_VFIO;
+	else
+		return -1;
+
+	/* parse the action type */
+	if (!strncmp(action, "add", 3))
+		event->type = RTE_DEV_EVENT_ADD;
+	else if (!strncmp(action, "remove", 6))
+		event->type = RTE_DEV_EVENT_REMOVE;
+	else
+		return -1;
+	return 0;
+}
+
+static void
+dev_delayed_unregister(void *param)
+{
+	rte_intr_callback_unregister(&intr_handle, dev_uev_handler, param);
+	close(intr_handle.fd);
+	intr_handle.fd = -1;
+}
+
+static void
+dev_uev_handler(__rte_unused void *param)
+{
+	struct rte_dev_event uevent;
+	int ret;
+	char buf[EAL_UEV_MSG_LEN];
+
+	memset(&uevent, 0, sizeof(struct rte_dev_event));
+	memset(buf, 0, EAL_UEV_MSG_LEN);
+
+	ret = recv(intr_handle.fd, buf, EAL_UEV_MSG_LEN, MSG_DONTWAIT);
+	if (ret < 0 && errno == EAGAIN)
+		return;
+	else if (ret <= 0) {
+		/* connection is closed or broken, can not up again. */
+		RTE_LOG(ERR, EAL, "uevent socket connection is broken.\n");
+		rte_eal_alarm_set(1, dev_delayed_unregister, NULL);
+		return;
+	}
+
+	ret = dev_uev_parse(buf, &uevent, EAL_UEV_MSG_LEN);
+	if (ret < 0) {
+		RTE_LOG(DEBUG, EAL, "It is not an valid event "
+			"that need to be handle.\n");
+		return;
+	}
+
+	RTE_LOG(DEBUG, EAL, "receive uevent(name:%s, type:%d, subsystem:%d)\n",
+		uevent.devname, uevent.type, uevent.subsystem);
+
+	if (uevent.devname)
+		dev_callback_process(uevent.devname, uevent.type);
+}
 
 int __rte_experimental
 rte_dev_event_monitor_start(void)
 {
-	/* TODO: start uevent monitor for linux */
+	int ret;
+
+	if (monitor_started)
+		return 0;
+
+	ret = dev_uev_socket_fd_create();
+	if (ret) {
+		RTE_LOG(ERR, EAL, "error create device event fd.\n");
+		return -1;
+	}
+
+	intr_handle.type = RTE_INTR_HANDLE_DEV_EVENT;
+	ret = rte_intr_callback_register(&intr_handle, dev_uev_handler, NULL);
+
+	if (ret) {
+		RTE_LOG(ERR, EAL, "fail to register uevent callback.\n");
+		return -1;
+	}
+
+	monitor_started = true;
+
 	return 0;
 }
 
 int __rte_experimental
 rte_dev_event_monitor_stop(void)
 {
-	/* TODO: stop uevent monitor for linux */
+	int ret;
+
+	if (!monitor_started)
+		return 0;
+
+	ret = rte_intr_callback_unregister(&intr_handle, dev_uev_handler,
+					   (void *)-1);
+	if (ret < 0) {
+		RTE_LOG(ERR, EAL, "fail to unregister uevent callback.\n");
+		return ret;
+	}
+
+	close(intr_handle.fd);
+	intr_handle.fd = -1;
+	monitor_started = false;
 	return 0;
 }