[CRIU] [PATCH v2 03/28] files: Send/receive fds with pointers on their struct fdinfo_list_entry in receiver

[Pavel Emelyanov]

On 11/30/2016 07:29 PM, Kirill Tkhai wrote:
> For moving to a single transport socket scheme, we need to be able to differ
> fds in receive queue from each other. Add a fle pointer as identifier for that.
> 
> v2: Rebase on compel
> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
> ---
>  criu/files.c         |   21 +++++++++++++++++++--
>  criu/include/files.h |    1 +
>  criu/pipes.c         |    2 +-
>  criu/sk-unix.c       |    2 +-
>  criu/tty.c           |    2 +-
>  5 files changed, 23 insertions(+), 5 deletions(-)
> 
> diff --git a/criu/files.c b/criu/files.c
> index e691558..c3ea2c4 100644
> --- a/criu/files.c
> +++ b/criu/files.c
> @@ -957,6 +957,23 @@ static int open_transport_fd(int pid, struct fdinfo_list_entry *fle)
>  	return -1;
>  }
>  
> +int recv_fd_from_peer(struct fdinfo_list_entry *fle)
> +{
> +	struct fdinfo_list_entry *tmp;
> +	int fd, ret;
> +
> +	ret = recv_fds(fle->fe->fd, &fd, 1, (void *)&tmp, sizeof(struct fdinfo_list_entry *));
> +	if (ret)
> +		return -1;
> +
> +	if (tmp != fle) {

Can this patch be applied by its own? I mean each pstree-item allocates its
own fle-s, their address cannot match to each other.

> +		pr_err("Received wrong fle\n");
> +		return -1;
> +	}
> +
> +	return fd;
> +}
> +
>  int send_fd_to_peer(int fd, struct fdinfo_list_entry *fle, int sock)
>  {
>  	struct sockaddr_un saddr;
> @@ -967,7 +984,7 @@ int send_fd_to_peer(int fd, struct fdinfo_list_entry *fle, int sock)
>  	transport_name_gen(&saddr, &len,
>  			futex_get(&fle->real_pid), fle->fe->fd);
>  	pr_info("\t\tSend fd %d to %s\n", fd, saddr.sun_path + 1);
> -	return send_fd(sock, &saddr, len, fd);
> +	return send_fds(sock, &saddr, len, &fd, 1, (void *)&fle, sizeof(struct fdinfo_list_entry *));
>  }
>  
>  static int send_fd_to_self(int fd, struct fdinfo_list_entry *fle, int sock)
> @@ -1077,7 +1094,7 @@ static int receive_fd(int pid, struct fdinfo_list_entry *fle)
>  
>  	pr_info("\tReceive fd for %d\n", fle->fe->fd);
>  
> -	tmp = recv_fd(fle->fe->fd);
> +	tmp = recv_fd_from_peer(fle);
>  	if (tmp < 0) {
>  		pr_err("Can't get fd %d\n", tmp);
>  		return -1;
> diff --git a/criu/include/files.h b/criu/include/files.h
> index 229c0d2..4f40e71 100644
> --- a/criu/include/files.h
> +++ b/criu/include/files.h
> @@ -148,6 +148,7 @@ extern int file_desc_add(struct file_desc *d, u32 id, struct file_desc_ops *ops)
>  extern struct fdinfo_list_entry *file_master(struct file_desc *d);
>  extern struct file_desc *find_file_desc_raw(int type, u32 id);
>  
> +extern int recv_fd_from_peer(struct fdinfo_list_entry *fle);
>  extern int send_fd_to_peer(int fd, struct fdinfo_list_entry *fle, int sock);
>  extern int restore_fown(int fd, FownEntry *fown);
>  extern int rst_file_params(int fd, FownEntry *fown, int flags);
> diff --git a/criu/pipes.c b/criu/pipes.c
> index 9fc87bd..31f436e 100644
> --- a/criu/pipes.c
> +++ b/criu/pipes.c
> @@ -237,7 +237,7 @@ static int recv_pipe_fd(struct pipe_info *pi)
>  
>  	pr_info("\tWaiting fd for %d\n", fd);
>  
> -	tmp = recv_fd(fd);
> +	tmp = recv_fd_from_peer(fle);
>  	if (tmp < 0) {
>  		pr_err("Can't get fd %d\n", tmp);
>  		return -1;
> diff --git a/criu/sk-unix.c b/criu/sk-unix.c
> index 202228d..74bd76d 100644
> --- a/criu/sk-unix.c
> +++ b/criu/sk-unix.c
> @@ -1096,7 +1096,7 @@ static int open_unixsk_pair_slave(struct unix_sk_info *ui)
>  	pr_info("Opening pair slave (id %#x ino %#x peer %#x) on %d\n",
>  			ui->ue->id, ui->ue->ino, ui->ue->peer, fle->fe->fd);
>  
> -	sk = recv_fd(fle->fe->fd);
> +	sk = recv_fd_from_peer(fle);
>  	if (sk < 0) {
>  		pr_err("Can't recv pair slave\n");
>  		return -1;
> diff --git a/criu/tty.c b/criu/tty.c
> index 7822a4f..6d0c8fa 100644
> --- a/criu/tty.c
> +++ b/criu/tty.c
> @@ -923,7 +923,7 @@ static int receive_tty(struct tty_info *info)
>  	fle = file_master(&info->d);
>  	pr_info("\tWaiting tty fd %d (pid %d)\n", fle->fe->fd, fle->pid);
>  
> -	fd = recv_fd(fle->fe->fd);
> +	fd = recv_fd_from_peer(fle);
>  	close(fle->fe->fd);
>  	if (fd < 0) {
>  		pr_err("Can't get fd %d\n", fd);
> 
> .
>