[dpdk-dev] [PATCH V19 3/4] eal/linux: uevent parse and process

[Guo, Jia]

On 4/5/2018 7:05 PM, Tan, Jianfeng wrote:
>
>
> On 4/5/2018 5:02 PM, Jeff Guo wrote:
>> 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>
>> ---
>> v19->18:
>> fix some misunderstanding part
>> ---
>>   lib/librte_eal/linuxapp/eal/eal_dev.c | 196 
>> +++++++++++++++++++++++++++++++++-
>>   1 file changed, 194 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..4686c41 100644
>> --- a/lib/librte_eal/linuxapp/eal/eal_dev.c
>> +++ b/lib/librte_eal/linuxapp/eal/eal_dev.c
>> @@ -2,21 +2,213 @@
>>    * 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 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, ret = 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
>> +        ret = -1;
>
> We can just return -1 here.
>
>>   +    /* 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
>> +        ret = -1;
>
> We can just return -1 here.
>
>> +    return ret;
>
> return 0 here.
>
>> +}
>> +
>> +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 || (ret < 0 && errno != EAGAIN)) {
>> +        /* connection is closed or broken, can not up again. */
>> +        RTE_LOG(ERR, EAL, "uevent socket connection is broken.\n");
>
> Again, we need an alarm to unregister the callback from intr thread.
>
ok.
>> +        return;
>> +    } else if (ret < 0) {
>> +        RTE_LOG(ERR, EAL,
>> +            "uevent socket read error(%d): %s.\n",
>> +            errno, strerror(errno));
>> +        return;
>> +    }
>
> I think the above code can be adjusted as:
>
>     if (ret == 0 || (ret < 0 && errno == EAGAIN))
>             return;
>     else if (ret < 0) {
>            RTE_LOG(ERR, EAL, "...");
>            set_alarm_to_unregister();
>     }
>
>
will check the best coding style.
>> +
>> +    ret = dev_uev_parse(buf, &uevent, EAL_UEV_MSG_LEN);
>> +    if (ret < 0) {
>> +        RTE_LOG(ERR, EAL, "It is not an valid event "
>
> s/ERR/DEBUG, or there are too many logs.
>
make sense.
>> +            "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;
>>   }
>