[CRIU] Re: [PATCH cr 09/12] pipes: add functions to restore pipes

[Pavel Emelyanov]

On 04/05/2012 03:47 PM, Andrey Vagin wrote:
> 
> Signed-off-by: Andrey Vagin <avagin at openvz.org>
> ---
>  files.c         |    5 ++
>  include/files.h |    4 ++
>  pipes.c         |  124 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 133 insertions(+), 0 deletions(-)
> 

> +int open_pipe(struct list_head *l)
> +{
> +	unsigned long time = 1000;
> +	struct pipe_info *pi, *pc, *p;
> +	int ret, tmp;
> +	int pfd[2];
> +	int sock;
> +	int create;
> +
> +	pi = container_of(l, struct pipe_info, fd_head);
> +
> +	pr_info("\tCreating pipe pipe_id=%x id=%x\n", pi->pe.pipe_id, pi->pe.id);
> +
> +	if (!pi->create)
> +		return recv_pipe_fd(pi);
> +
> +	if (pipe(pfd) < 0) {
> +		pr_perror("Can't create pipe");
> +		return -1;
> +	}
> +
> +	sock = socket(PF_UNIX, SOCK_DGRAM, 0);
> +	if (sock < 0) {
> +		pr_perror("Can't create socket");
> +		return -1;
> +	}
> +
> +	list_for_each_entry(p, &pi->pipe_list, pipe_list) {
> +		int len, fd;
> +		struct sockaddr_un saddr;
> +		struct fdinfo_list_entry *fle;
> +
> +		BUG_ON(list_empty(&p->fd_head));
> +		fle = list_first_entry(&p->fd_head,
> +				struct fdinfo_list_entry, list);
> +
> +		pr_info("\t\tWait fdinfo pid=%d fd=%d\n", fle->pid, fle->fd);
> +		futex_wait_while(&fle->real_pid, 0);
> +
> +		transport_name_gen(&saddr, &len,
> +				futex_get(&fle->real_pid), fle->fd);
> +
> +		fd = pfd[p->pe.flags & O_WRONLY];
> +
> +		pr_info("\t\tSend fd %d to %s\n", fd, saddr.sun_path + 1);
> +
> +		if (send_fd(sock, &saddr, len, fd) < 0) {

This looks strange. You send an fd to other task to make it re-open it in
his /proc/pid/fd. Why not just make it open ours /proc/pid/fd ?

> +			pr_perror("Can't send file descriptor");
> +			return -1;
> +		}
> +	}
> +
> +	close(sock);
> +
> +out:
> +	close(pfd[!(pi->pe.flags & O_WRONLY)]);
> +	tmp = pfd[pi->pe.flags & O_WRONLY];
> +	ret = set_fd_flags(tmp, pi->pe.flags);
> +	if (ret < 0)
> +		return -1;
> +
> +	return tmp;
> +}