[PATCH 4/8] mdev: re-initialize if uevent messages were lost

[Denys Vlasenko]

Applied, thanks

On Mon, Dec 16, 2019 at 10:57 PM Jan Klötzke <jan at kloetzke.net> wrote:
>
> If the netlink read() failed with ENOBUFS we know that we have missed at
> least one message due to a socket receive buffer overrun. The only way
> how to recover is to drop the old socket, open a fresh one and make a
> cold-plug scan of the current system state.
>
> Signed-off-by: Jan Klötzke <jan at kloetzke.net>
> ---
>  util-linux/mdev.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/util-linux/mdev.c b/util-linux/mdev.c
> index cfc1a38bc..91c4ff466 100644
> --- a/util-linux/mdev.c
> +++ b/util-linux/mdev.c
> @@ -1206,6 +1206,16 @@ static void daemon_loop(char *temp, int fd)
>
>                 len = safe_read(fd, netbuf, sizeof(netbuf) - 1);
>                 if (len < 0) {
> +                       if (errno == ENOBUFS) {
> +                               /*
> +                                * We ran out of socket receive buffer space.
> +                                * Start from scratch.
> +                                */
> +                               dbg1s("uevent overrun! Rescanning...");
> +                               close(fd);
> +                               fd = daemon_init(temp);
> +                               continue;
> +                       }
>                         bb_simple_perror_msg_and_die("read");
>                 }
>                 end = netbuf + len;
> --
> 2.20.1
>
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