[dpdk-dev] [PATCH V18 3/4] eal/linux: uevent parse and process

[Tan, Jianfeng]

Hi Jeff,

Looks much better now, but still have some issues to address.

> -----Original Message-----
> From: Guo, Jia
> Sent: Tuesday, April 3, 2018 6:34 PM
> To: stephen at networkplumber.org; Richardson, Bruce; Yigit, Ferruh;
> Ananyev, Konstantin; gaetan.rivet at 6wind.com; Wu, Jingjing;
> thomas at monjalon.net; motih at mellanox.com; Van Haaren, Harry; Tan,
> Jianfeng
> Cc: jblunck at infradead.org; shreyansh.jain at nxp.com; dev at dpdk.org; Guo,
> Jia; Zhang, Helin
> Subject: [PATCH V18 3/4] eal/linux: 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 at intel.com>
> ---
> v18->v17:
> refine socket configuration.
> ---
>  lib/librte_eal/linuxapp/eal/eal_dev.c | 178
> +++++++++++++++++++++++++++++++++-
>  1 file changed, 176 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/librte_eal/linuxapp/eal/eal_dev.c
> b/lib/librte_eal/linuxapp/eal/eal_dev.c
> index 9c8d1a0..9f2ee40 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_dev.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_dev.c
> @@ -2,21 +2,195 @@
>   * 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 "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
> +
> +/* identify the system layer which event exposure from */

Reword it a little bit: 
    /* 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 socket for netlink fd.\n");

Reword it a little bit so that we can understand it's a log related to hotplug:
    Failed to bind uevent socket

> +		goto err;
> +	}
> +
> +	return 0;
> +err:
> +	close(intr_handle.fd);

Then: intr_handle.fd = -1?

> +	return ret;
> +}
> +
> +static void
> +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++;
> +		}
> +		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++;
> +		}
> +	}
> +
> +	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))

How can we indicate it is an event with subsystem that we will not handle?

> +		event->subsystem = EAL_DEV_EVENT_SUBSYSTEM_VFIO;
> +	if (!strncmp(action, "add", 3))
> +		event->type = RTE_DEV_EVENT_ADD;
> +	if (!strncmp(action, "remove", 6))
> +		event->type = RTE_DEV_EVENT_REMOVE;

How can we indicate it is an event with type that we will not handle?

My suggestion is to define a return value for that:
- EVENT_VALID returned for an event that we will handle later.
- EVENT_INVALID returned for any unknown events.

> +}
> +
> +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));
> +		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))

If error happens, we shall start an alarm task to remove the callback of interrupt thread.

> +		return;

You may want to add a log here for debugging, showing what event comes for which device.

> 
> +	if (uevent.devname)

You can also filter this kind of events using the way I suggested above.

> +		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_process,
> 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_process,
> +					   (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;
>  }
> --
> 2.7.4