[dpdk-dev] [PATCH V16 3/4] eal/linux: uevent parse and process

[Tan, Jianfeng]

BTW, adding new .c file needs to update meson.build now.

On 3/26/2018 7:20 PM, Jeff Guo wrote:
> In order to handle the uevent which have been detected from the kernel
> side, add uevent parse and process function to translate the uevent into
> device event, which user has subscribe to monitor.
>
> Signed-off-by: Jeff Guo <jia.guo at intel.com>
> ---
> 1.move all linux specific together
> ---
>   lib/librte_eal/linuxapp/eal/eal_dev.c | 214 +++++++++++++++++++++++++++++++++-
>   1 file changed, 211 insertions(+), 3 deletions(-)
>
> diff --git a/lib/librte_eal/linuxapp/eal/eal_dev.c b/lib/librte_eal/linuxapp/eal/eal_dev.c
> index 5ab5830..90094c0 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_dev.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_dev.c
> @@ -2,19 +2,227 @@
>    * Copyright(c) 2018 Intel Corporation
>    */
>   
> -#include <rte_log.h>
> +#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>

Some header files are not necessary, the above one for example.

> +#include <stdbool.h>
> +#include <fcntl.h>
> +
> +#include <rte_malloc.h>
> +#include <rte_bus.h>
>   #include <rte_dev.h>
> +#include <rte_devargs.h>

We don't need this one neither.

> +#include <rte_debug.h>
> +#include <rte_log.h>
> +#include <rte_interrupts.h>
> +
> +#include "eal_private.h"
> +#include "eal_thread.h"

Ditto.

> +
> +static struct rte_intr_handle intr_handle = {.fd = -1 };

I don't think we need a static intr_handle, what we need is the monitor fd.

> +static bool monitor_not_started = true;
> +
> +#define EAL_UEV_MSG_LEN 4096
> +#define EAL_UEV_MSG_ELEM_LEN 128
> +
> +/* identify the system layer which event exposure from */
> +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_MAX
> +};
> +
> +static int
> +dev_uev_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_uev_monitor_create(int netlink_fd)

I think we should merge this function with above function. I don't see a 
reason to split into two functions.

> +{
> +	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");

Please print more information here, so that we don't have to check the 
code if we really encounter such an error.

> +		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 void
> +dev_uev_parse(const char *buf, struct rte_dev_event *event, int length)

We always get an event we care? If no, we need return something so that 
the caller can skip this event.

> +{
> +	char action[EAL_UEV_MSG_ELEM_LEN];
> +	char subsystem[EAL_UEV_MSG_ELEM_LEN];
> +	char dev_path[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(dev_path, 0, EAL_UEV_MSG_ELEM_LEN);
> +	memset(pci_slot_name, 0, EAL_UEV_MSG_ELEM_LEN);

I did not see you need dev_path, why do we care to parse it?

> +
> +	while (i < length) {
> +		for (; i < length; i++) {
> +			if (*buf)
> +				break;
> +			buf++;
> +		}
> +		if (!strncmp(buf, "ACTION=", 7)) {
> +			buf += 7;
> +			i += 7;
> +			snprintf(action, sizeof(action), "%s", buf);
> +		} else if (!strncmp(buf, "DEVPATH=", 8)) {
> +			buf += 8;
> +			i += 8;
> +			snprintf(dev_path, sizeof(dev_path), "%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 = pci_slot_name;

You are assigning a stack pointer for the caller to use; this is 
dangerous, we should never do that.

> +		}
> +		for (; i < length; i++) {
> +			if (*buf == '\0')
> +				break;
> +			buf++;
> +		}
> +	}
> +
> +	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;
> +	if (!strncmp(action, "add", 3))
> +		event->type = RTE_DEV_EVENT_ADD;
> +	if (!strncmp(action, "remove", 6))
> +		event->type = RTE_DEV_EVENT_REMOVE;
> +}
> +
> +static int
> +dev_uev_receive(int fd, 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(fd, buf, EAL_UEV_MSG_LEN, MSG_DONTWAIT);
> +	if (ret < 0) {
> +		RTE_LOG(ERR, EAL,
> +		"Socket read error(%d): %s\n",
> +		errno, strerror(errno));

The above three lines are in bad format.

> +		return -1;
> +	} else if (ret == 0)
> +		/* connection closed */
> +		return -1;
> +
> +	dev_uev_parse(buf, uevent, EAL_UEV_MSG_LEN);
> +
> +	return 0;
> +}
> +
> +static void
> +dev_uev_process(__rte_unused void *param)
> +{
> +	struct rte_dev_event uevent;
> +
> +	if (dev_uev_receive(intr_handle.fd, &uevent))
> +		return;
> +
> +	if (uevent.devname)
> +		dev_callback_process(uevent.devname, uevent.type, NULL);
> +}
>   
>   int __rte_experimental
>   rte_dev_event_monitor_start(void)
>   {
> -	/* TODO: start uevent monitor for linux */
> +	int ret;
> +
> +	if (!monitor_not_started)
> +		return 0;
> +
> +	intr_handle.fd = dev_uev_monitor_fd_new();
> +	intr_handle.type = RTE_INTR_HANDLE_DEV_EVENT;
> +
> +	ret = dev_uev_monitor_create(intr_handle.fd);
> +
> +	if (ret) {
> +		RTE_LOG(ERR, EAL, "error create device event monitor\n");
> +		return -1;
> +	}
> +
> +	ret = rte_intr_callback_register(&intr_handle, dev_uev_process, NULL);
> +
> +	if (ret) {
> +		RTE_LOG(ERR, EAL, "fail to register uevent callback\n");
> +		return -1;
> +	}
> +
> +	monitor_not_started = false;
> +
>   	return 0;
>   }
>   
>   int __rte_experimental
>   rte_dev_event_monitor_stop(void)
>   {
> -	/* TODO: stop uevent monitor for linux */
> +	int ret;
> +
> +	if (monitor_not_started)
> +		return 0;
> +
> +	ret = rte_intr_callback_unregister(&intr_handle, dev_uev_process, NULL);
> +	if (ret) {
> +		RTE_LOG(ERR, EAL, "fail to unregister uevent callback");
> +		return ret;
> +	}
> +
> +	close(intr_handle.fd);
> +	intr_handle.fd = -1;
> +	monitor_not_started = true;
>   	return 0;
>   }