[CRIU] [PATCH v3 1/2] unix: Add support for restoring receive queue for unix DGRAM sockets

[Pavel Emelyanov]

> @@ -1133,6 +1133,40 @@ static int open_unixsk_standalone(struct unix_sk_info *ui)
>  
>  		close(sks[1]);
>  		sk = sks[0];
> +	} else if (ui->ue->type == SOCK_DGRAM) {

I saw your response about SOCK_STREAM sockets in the previous version of
the patch, but still want to get back to this discussion.

I'm not sure that the problem doesn't exist for stream sockets as you
say. What happens if we do socketpair(PF_UNIX, SOCK_STREAM), then send 
data from sk[0] to sk[1] and then close(sk[0])? Is this supported by
CRIU, do we have such a test and which code handles the sk[1]'s queue 
restore?

-- Pavel

> +		struct sockaddr_un addr;
> +		int sks[2];
> +
> +		if (socketpair(PF_UNIX, ui->ue->type, 0, sks) < 0) {
> +			pr_perror("Can't create socketpair");
> +			return -1;
> +		}
> +
> +		sk = sks[0];
> +		addr.sun_family = AF_UNSPEC;
> +
> +		/*
> +		 * socketpair() assigns sks[1] as a peer of sks[0]
> +		 * (and vice versa). But in this case (not zero peer)
> +		 * it's impossible for other sockets to connect
> +		 * to sks[0] (see unix_dgram_connect()->unix_may_send()).
> +		 * The below is hack: we use that connect with AF_UNSPEC
> +