[dpdk-dev] [PATCH V13 1/3] eal: add uevent monitor api and callback func

[Jeff Guo]

This patch aim to add a general uevent mechanism in eal device layer,
to enable all linux kernel object uevent monitoring, user could use these
APIs to monitor and read out the device status info that sent from the
kernel side, then corresponding to handle it, such as when detect hotplug
uevent type, user could detach or attach the device, and more it benefit
to use to do smoothly fail safe work.

About uevent monitoring:
a: add one epolling to poll the netlink socket, to monitor the uevent of
   the device.
b: add enum of rte_eal_dev_event_type and struct of rte_eal_uevent.
c: add below APIs in rte eal device layer.
   rte_dev_callback_register
   rte_dev_callback_unregister
   _rte_dev_callback_process
   rte_dev_event_monitor_start
   rte_dev_event_monitor_stop

Signed-off-by: Jeff Guo <jia.guo at intel.com>
---
v13->v12:
fix some logic issue and null check issue
fix monitor stop func issue and bsp build issue
---
 lib/librte_eal/bsdapp/eal/Makefile      |   1 +
 lib/librte_eal/bsdapp/eal/eal_dev.c     |  38 +++++
 lib/librte_eal/common/eal_common_dev.c  | 133 +++++++++++++++++
 lib/librte_eal/common/include/rte_dev.h | 119 ++++++++++++++++
 lib/librte_eal/linuxapp/eal/Makefile    |   1 +
 lib/librte_eal/linuxapp/eal/eal_dev.c   | 243 ++++++++++++++++++++++++++++++++
 6 files changed, 535 insertions(+)
 create mode 100644 lib/librte_eal/bsdapp/eal/eal_dev.c
 create mode 100644 lib/librte_eal/linuxapp/eal/eal_dev.c

diff --git a/lib/librte_eal/bsdapp/eal/Makefile b/lib/librte_eal/bsdapp/eal/Makefile
index c694076..5ff74d0 100644
--- a/lib/librte_eal/bsdapp/eal/Makefile
+++ b/lib/librte_eal/bsdapp/eal/Makefile
@@ -32,6 +32,7 @@ SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_lcore.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_timer.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_interrupts.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_alarm.c
+SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_dev.c
 
 # from common dir
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += eal_common_lcore.c
diff --git a/lib/librte_eal/bsdapp/eal/eal_dev.c b/lib/librte_eal/bsdapp/eal/eal_dev.c
new file mode 100644
index 0000000..83ffdee
--- /dev/null
+++ b/lib/librte_eal/bsdapp/eal/eal_dev.c
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2018 Intel Corporation
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <inttypes.h>
+#include <sys/queue.h>
+#include <sys/signalfd.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/epoll.h>
+#include <unistd.h>
+#include <signal.h>
+#include <stdbool.h>
+
+#include <rte_malloc.h>
+#include <rte_bus.h>
+#include <rte_dev.h>
+#include <rte_devargs.h>
+#include <rte_debug.h>
+#include <rte_log.h>
+
+#include "eal_thread.h"
+
+int
+rte_dev_event_monitor_start(void)
+{
+	RTE_LOG(ERR, EAL, "Not support event monitor for FreeBSD\n");
+	return -1;
+}
+
+int
+rte_dev_event_monitor_stop(void)
+{
+	RTE_LOG(ERR, EAL, "Not support event monitor for FreeBSD\n");
+	return -1;
+}
diff --git a/lib/librte_eal/common/eal_common_dev.c b/lib/librte_eal/common/eal_common_dev.c
index dda8f58..dbeb670 100644
--- a/lib/librte_eal/common/eal_common_dev.c
+++ b/lib/librte_eal/common/eal_common_dev.c
@@ -42,9 +42,31 @@
 #include <rte_devargs.h>
 #include <rte_debug.h>
 #include <rte_log.h>
+#include <rte_spinlock.h>
+#include <rte_malloc.h>
 
 #include "eal_private.h"
 
+/* spinlock for device callbacks */
+static rte_spinlock_t rte_dev_event_lock = RTE_SPINLOCK_INITIALIZER;
+
+/**
+ * The user application callback description.
+ *
+ * It contains callback address to be registered by user application,
+ * the pointer to the parameters for callback, and the device name.
+ */
+struct rte_dev_event_callback {
+	TAILQ_ENTRY(rte_dev_event_callback) next; /**< Callbacks list */
+	rte_dev_event_cb_fn cb_fn;                /**< Callback address */
+	void *cb_arg;                           /**< Callback parameter */
+	char *dev_name;	 /**< Callback devcie name, NULL is for all device */
+	uint32_t active;                        /**< Callback is executing */
+};
+
+/* A general callbacks list for all callback of devices */
+static struct rte_dev_event_cb_list dev_event_cbs;
+
 static int cmp_detached_dev_name(const struct rte_device *dev,
 	const void *_name)
 {
@@ -234,3 +256,114 @@ int rte_eal_hotplug_remove(const char *busname, const char *devname)
 	rte_eal_devargs_remove(busname, devname);
 	return ret;
 }
+
+int
+rte_dev_callback_register(char *device_name, rte_dev_event_cb_fn cb_fn,
+				void *cb_arg)
+{
+	struct rte_dev_event_callback *event_cb = NULL;
+
+	rte_spinlock_lock(&rte_dev_event_lock);
+
+	if (TAILQ_EMPTY(&(dev_event_cbs)))
+		TAILQ_INIT(&(dev_event_cbs));
+
+	TAILQ_FOREACH(event_cb, &(dev_event_cbs), next) {
+		if (event_cb->cb_fn == cb_fn &&
+			event_cb->cb_arg == cb_arg &&
+			((!device_name && !event_cb->dev_name) ? 1 :
+			(!strcmp(event_cb->dev_name, device_name))))
+			break;
+	}
+
+	/* create a new callback. */
+	if (event_cb == NULL) {
+		/* allocate a new user callback entity */
+		event_cb = malloc(sizeof(struct rte_dev_event_callback));
+		if (event_cb != NULL) {
+			event_cb->cb_fn = cb_fn;
+			event_cb->cb_arg = cb_arg;
+			event_cb->dev_name = !device_name ? NULL :
+				strcpy(event_cb->dev_name, device_name);
+			TAILQ_INSERT_TAIL(&(dev_event_cbs), event_cb, next);
+		} else
+			free(event_cb);
+	}
+
+	rte_spinlock_unlock(&rte_dev_event_lock);
+	return (event_cb == NULL) ? -1 : 0;
+}
+
+int
+rte_dev_callback_unregister(char *device_name, rte_dev_event_cb_fn cb_fn,
+				void *cb_arg)
+{
+	int ret;
+	struct rte_dev_event_callback *event_cb, *next;
+
+	if (!cb_fn || device_name == NULL)
+		return -EINVAL;
+
+	rte_spinlock_lock(&rte_dev_event_lock);
+
+	ret = 0;
+
+	for (event_cb = TAILQ_FIRST(&(dev_event_cbs)); event_cb != NULL;
+	      event_cb = next) {
+
+		next = TAILQ_NEXT(event_cb, next);
+
+		if (event_cb->cb_fn != cb_fn ||
+				(event_cb->cb_arg != (void *)-1 &&
+				event_cb->cb_arg != cb_arg) ||
+				(((!device_name && event_cb->dev_name) ||
+				(device_name && !event_cb->dev_name)) ? 1 :
+				strcmp(event_cb->dev_name, device_name)))
+			continue;
+
+		/*
+		 * if this callback is not executing right now,
+		 * then remove it.
+		 */
+		if (event_cb->active == 0) {
+			TAILQ_REMOVE(&(dev_event_cbs), event_cb, next);
+			rte_free(event_cb);
+		} else {
+			ret = -EAGAIN;
+		}
+	}
+
+	rte_spinlock_unlock(&rte_dev_event_lock);
+	return ret;
+}
+
+int
+_rte_dev_callback_process(char *device_name, enum rte_dev_event_type event,
+				void *cb_arg)
+{
+	struct rte_dev_event_callback dev_cb;
+	struct rte_dev_event_callback *cb_lst;
+	int rc = 0;
+
+	rte_spinlock_lock(&rte_dev_event_lock);
+
+	if (device_name == NULL)
+		return -EINVAL;
+
+	TAILQ_FOREACH(cb_lst, &(dev_event_cbs), next) {
+		if (cb_lst->cb_fn == NULL || (!cb_lst->dev_name ? 0 :
+			strcmp(cb_lst->dev_name,
+			device_name) && cb_lst->dev_name))
+			continue;
+		dev_cb = *cb_lst;
+		cb_lst->active = 1;
+		if (cb_arg)
+			dev_cb.cb_arg = cb_arg;
+		rc = dev_cb.cb_fn(device_name, event,
+				dev_cb.cb_arg);
+		cb_lst->active = 0;
+	}
+
+	rte_spinlock_unlock(&rte_dev_event_lock);
+	return rc;
+}
diff --git a/lib/librte_eal/common/include/rte_dev.h b/lib/librte_eal/common/include/rte_dev.h
index 8088dcc..88fbb2d 100644
--- a/lib/librte_eal/common/include/rte_dev.h
+++ b/lib/librte_eal/common/include/rte_dev.h
@@ -52,6 +52,30 @@ extern "C" {
 #include <rte_config.h>
 #include <rte_log.h>
 
+/**
+ * The device event type.
+ */
+enum rte_dev_event_type {
+	RTE_DEV_EVENT_UNKNOWN,	/**< unknown event type */
+	RTE_DEV_EVENT_ADD,	/**< device being added */
+	RTE_DEV_EVENT_REMOVE,	/**< device being removed */
+	RTE_DEV_EVENT_MAX	/**< max value of this enum */
+};
+
+struct rte_dev_event {
+	enum rte_dev_event_type type;	/**< device event type */
+	int subsystem;			/**< subsystem id */
+	char *devname;			/**< device name */
+};
+
+typedef int (*rte_dev_event_cb_fn)(char *device_name,
+					enum rte_dev_event_type event,
+					void *cb_arg);
+
+struct rte_dev_event_callback;
+/** @internal Structure to keep track of registered callbacks */
+TAILQ_HEAD(rte_dev_event_cb_list, rte_dev_event_callback);
+
 __attribute__((format(printf, 2, 0)))
 static inline void
 rte_pmd_debug_trace(const char *func_name, const char *fmt, ...)
@@ -294,4 +318,99 @@ __attribute__((used)) = str
 }
 #endif
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * It registers the callback for the specific device.
+ * Multiple callbacks cal be registered at the same time.
+ *
+ * @param device_name
+ *  The device name, that is the param name of the struct rte_device,
+ *  null value means for all devices.
+ * @param cb_fn
+ *  callback address.
+ * @param cb_arg
+ *  address of parameter for callback.
+ *
+ * @return
+ *  - On success, zero.
+ *  - On failure, a negative value.
+ */
+int rte_dev_callback_register(char *device_name, rte_dev_event_cb_fn cb_fn,
+					void *cb_arg);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * It unregisters the callback according to the specified device.
+ *
+ * @param device_name
+ *  The device name, that is the param name of the struct rte_device,
+ *  null value means for all devices.
+ * @param cb_fn
+ *  callback address.
+ * @param cb_arg
+ *  address of parameter for callback, (void *)-1 means to remove all
+ *  registered which has the same callback address.
+ *
+ * @return
+ *  - On success, return the number of callback entities removed.
+ *  - On failure, a negative value.
+ */
+int rte_dev_callback_unregister(char *device_name, rte_dev_event_cb_fn cb_fn,
+					void *cb_arg);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * internal Executes all the user application registered callbacks for
+ * the specific device. It is for DPDK internal user only. User
+ * application should not call it directly.
+ *
+ * @param device_name
+ *  The device name.
+ * @param event
+ *  the device event type
+ *  is permitted or not.
+ * @param cb_arg
+ *  callback parameter.
+ *
+ * @return
+ *  - On success, return zero.
+ *  - On failure, a negative value.
+ */
+int
+_rte_dev_callback_process(char *device_name, enum rte_dev_event_type event,
+				void *cb_arg);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Start the device event monitoring.
+ *
+ * @param none
+ * @return
+ *   - On success, zero.
+ *   - On failure, a negative value.
+ */
+int
+rte_dev_event_monitor_start(void);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Stop the device event monitoring .
+ *
+ * @param none
+ * @return
+ *   - On success, zero.
+ *   - On failure, a negative value.
+ */
+int
+rte_dev_event_monitor_stop(void);
 #endif /* _RTE_DEV_H_ */
diff --git a/lib/librte_eal/linuxapp/eal/Makefile b/lib/librte_eal/linuxapp/eal/Makefile
index 7bf278f..a167401 100644
--- a/lib/librte_eal/linuxapp/eal/Makefile
+++ b/lib/librte_eal/linuxapp/eal/Makefile
@@ -39,6 +39,7 @@ SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_lcore.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_timer.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_interrupts.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_alarm.c
+SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_dev.c
 
 # from common dir
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += eal_common_lcore.c
diff --git a/lib/librte_eal/linuxapp/eal/eal_dev.c b/lib/librte_eal/linuxapp/eal/eal_dev.c
new file mode 100644
index 0000000..887884c
--- /dev/null
+++ b/lib/librte_eal/linuxapp/eal/eal_dev.c
@@ -0,0 +1,243 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2018 Intel Corporation
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <inttypes.h>
+#include <sys/queue.h>
+#include <sys/signalfd.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <linux/netlink.h>
+#include <sys/epoll.h>
+#include <unistd.h>
+#include <signal.h>
+#include <stdbool.h>
+
+#include <rte_malloc.h>
+#include <rte_bus.h>
+#include <rte_dev.h>
+#include <rte_devargs.h>
+#include <rte_debug.h>
+#include <rte_log.h>
+#include <rte_service.h>
+#include <rte_service_component.h>
+
+#include "eal_thread.h"
+
+bool service_exit = true;
+bool service_no_init = true;
+uint32_t slcore;
+uint32_t sevice_id;
+#define DEV_EV_MNT_SERVICE_NAME "device_event_monitor_service"
+
+static int
+dev_monitor_fd_new(void)
+{
+
+	int uevent_fd;
+
+	uevent_fd = socket(PF_NETLINK, SOCK_RAW | SOCK_CLOEXEC |
+			SOCK_NONBLOCK,
+			NETLINK_KOBJECT_UEVENT);
+	if (uevent_fd < 0) {
+		RTE_LOG(ERR, EAL, "create uevent fd failed\n");
+		return -1;
+	}
+	return uevent_fd;
+}
+
+static int
+dev_monitor_enable(int netlink_fd)
+{
+	struct sockaddr_nl addr;
+	int ret;
+	int size = 64 * 1024;
+	int nonblock = 1;
+
+	memset(&addr, 0, sizeof(addr));
+	addr.nl_family = AF_NETLINK;
+	addr.nl_pid = 0;
+	addr.nl_groups = 0xffffffff;
+
+	if (bind(netlink_fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
+		RTE_LOG(ERR, EAL, "bind failed\n");
+		goto err;
+	}
+
+	setsockopt(netlink_fd, SOL_SOCKET, SO_PASSCRED, &size, sizeof(size));
+
+	ret = ioctl(netlink_fd, FIONBIO, &nonblock);
+	if (ret != 0) {
+		RTE_LOG(ERR, EAL, "ioctl(FIONBIO) failed\n");
+		goto err;
+	}
+	return 0;
+err:
+	close(netlink_fd);
+	return -1;
+}
+
+static int
+dev_uev_process(__rte_unused struct epoll_event *events, __rte_unused int nfds)
+{
+	/* TODO: device uevent processing */
+	return 0;
+}
+
+/**
+ * It builds/rebuilds up the epoll file descriptor with all the
+ * file descriptors being waited on. Then handles the netlink event.
+ *
+ * @param arg
+ *  pointer. (unused)
+ *
+ * @return
+ *   - On success, zero.
+ *   - On failure, a negative value.
+ */
+static int32_t dev_uev_monitoring(__rte_unused void *arg)
+{
+	int netlink_fd = -1;
+	struct epoll_event ep_kernel;
+	int fd_ep = -1;
+
+	service_exit = false;
+
+	fd_ep = epoll_create1(EPOLL_CLOEXEC);
+	if (fd_ep < 0) {
+		RTE_LOG(ERR, EAL, "error creating epoll fd: %m\n");
+		goto out;
+	}
+
+	netlink_fd = dev_monitor_fd_new();
+
+	if (dev_monitor_enable(netlink_fd) < 0) {
+		RTE_LOG(ERR, EAL, "error subscribing to kernel events\n");
+		goto out;
+	}
+
+	memset(&ep_kernel, 0, sizeof(struct epoll_event));
+	ep_kernel.events = EPOLLIN | EPOLLPRI | EPOLLRDHUP | EPOLLHUP;
+	ep_kernel.data.fd = netlink_fd;
+	if (epoll_ctl(fd_ep, EPOLL_CTL_ADD, netlink_fd,
+		&ep_kernel) < 0) {
+		RTE_LOG(ERR, EAL, "error addding fd to epoll: %m\n");
+		goto out;
+	}
+
+	while (!service_exit) {
+		int fdcount;
+		struct epoll_event ev[1];
+
+		fdcount = epoll_wait(fd_ep, ev, 1, -1);
+		if (fdcount < 0) {
+			if (errno != EINTR)
+				RTE_LOG(ERR, EAL, "error receiving uevent "
+					"message: %m\n");
+				continue;
+			}
+
+		/* epoll_wait has at least one fd ready to read */
+		if (dev_uev_process(ev, fdcount) < 0) {
+			if (errno != EINTR)
+				RTE_LOG(ERR, EAL, "error processing uevent "
+					"message: %m\n");
+		}
+	}
+	return 0;
+out:
+	if (fd_ep >= 0)
+		close(fd_ep);
+	if (netlink_fd >= 0)
+		close(netlink_fd);
+	rte_panic("uev monitoring fail\n");
+	return -1;
+}
+
+int
+rte_dev_event_monitor_start(void)
+{
+	int ret;
+	struct rte_service_spec service;
+	const uint32_t sid = 0;
+
+	if (!service_no_init)
+		return 0;
+
+	slcore = rte_get_next_lcore(/* start core */ -1,
+					       /* skip master */ 1,
+					       /* wrap */ 0);
+
+	ret = rte_service_lcore_add(slcore);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "dev event monitor lcore add fail");
+		return ret;
+	}
+
+	memset(&service, 0, sizeof(service));
+	snprintf(service.name, sizeof(service.name), DEV_EV_MNT_SERVICE_NAME);
+
+	service.socket_id = rte_socket_id();
+	service.callback = dev_uev_monitoring;
+	service.callback_userdata = NULL;
+	service.capabilities = 0;
+	ret = rte_service_component_register(&service, &sevice_id);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Failed to register service %s "
+			"err = %" PRId32,
+			service.name, ret);
+		return ret;
+	}
+	ret = rte_service_runstate_set(sid, 1);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Failed to set the runstate of "
+			"the service");
+		goto err_done;
+	}
+	ret = rte_service_component_runstate_set(sevice_id, 1);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Failed to set the backend runstate"
+			" of a component");
+		return ret;
+	}
+	ret = rte_service_map_lcore_set(sid, slcore, 1);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Failed to enable lcore 1 on "
+			"dev event monitor service");
+		return ret;
+	}
+	rte_service_lcore_start(slcore);
+	service_no_init = false;
+	return 0;
+
+err_done:
+	rte_service_component_unregister(sevice_id);
+	return ret;
+}
+
+int
+rte_dev_event_monitor_stop(void)
+{
+	int ret;
+
+	ret = rte_service_lcore_stop(slcore);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Failed to stop lcore on "
+			"dev event monitor service");
+		return ret;
+	}
+
+	rte_service_component_unregister(sevice_id);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Failed to unregister service "
+			"err = %" PRId32, ret);
+		return ret;
+	}
+
+	service_exit = true;
+	service_no_init = true;
+
+	return 0;
+}
-- 
2.7.4