[EXTERNAL] [PATCH v5 2/4] eal/linux: increase uevent socket buffer

[Long Li]

> The kernel netlink socket into DPDK can get overrun if DPDK interrupt thread is
> not keeping up. To reduce the possibility increase the socket receive buffer to
> 4M.
> 
> Fixes: 0d0f478d0483 ("eal/linux: add uevent parse and process")
> Cc: stable at dpdk.org
> 
> Reported-by: Randy Tice <rtice at cisco.com>
> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>

Reviewed-by: Long Li <longli at microsoft.com>


> ---
>  lib/eal/linux/eal_dev.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/lib/eal/linux/eal_dev.c b/lib/eal/linux/eal_dev.c index
> 666967667f..fb5c8bf070 100644
> --- a/lib/eal/linux/eal_dev.c
> +++ b/lib/eal/linux/eal_dev.c
> @@ -32,6 +32,9 @@ static bool hotplug_handle;
>  /* Listen only to messages from kernel (not libudev) */  #define
> EAL_UEV_GROUP_KERNEL 1
> 
> +/* Large uevent buffer */
> +#define EAL_UEV_MSG_RCVBUF (4 * 1024 * 1024)
> +
>  /*
>   * spinlock for device hot-unplug failure handling. If it try to access bus or
>   * device, such as handle sigbus on bus or handle memory failure for device
> @@ -103,6 +106,29 @@ static int cmp_dev_name(const struct rte_device
> *dev,
>  	return strcmp(dev->name, name);
>  }
> 
> +/*
> + * To avoid losing uevents increase the netlink receive buffer size,
> + * and override the kernel clamp value if necessary.
> + */
> +static int
> +dev_uev_set_rcvbuf(int fd, int n)
> +{
> +	int ret, val;
> +	socklen_t len = sizeof(val);
> +
> +	ret = setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &n, sizeof(n));
> +	if (ret < 0)
> +		return ret;
> +
> +	/* kernel may have clamped our request */
> +	ret = getsockopt(fd, SOL_SOCKET, SO_RCVBUF, &val, &len);
> +	if (ret >= 0 && len == sizeof(val) && val == n * 2)
> +		return 0; /* request worked */
> +
> +	/* try again to override kernel restriction */
> +	return setsockopt(fd, SOL_SOCKET, SO_RCVBUFFORCE, &n, sizeof(n)); }
> +
>  static int
>  dev_uev_socket_fd_create(void)
>  {
> @@ -127,6 +153,9 @@ dev_uev_socket_fd_create(void)
>  		goto err;
>  	}
> 
> +	if (dev_uev_set_rcvbuf(fd, EAL_UEV_MSG_RCVBUF) < 0)
> +		EAL_LOG(NOTICE, "Failed to set rcvbuf.");
> +
>  	if (rte_intr_fd_set(intr_handle, fd))
>  		goto err;
> 
> --
> 2.53.0