[CRIU] [PATCH RFC 03/30] files: Wait transport_fd before sending a fd to peer

[Pavel Emelyanov]

On 11/01/2016 05:30 PM, Kirill Tkhai wrote:
> Now it's excess, because we already wait per-fd transport
> sockets. But this will be used in next patches.
> 
> Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
> ---
>  criu/files.c          |    2 ++
>  criu/include/pstree.h |    7 +++++++
>  criu/pstree.c         |    1 +
>  3 files changed, 10 insertions(+)
> 
> diff --git a/criu/files.c b/criu/files.c
> index e869614..97b4e95 100644
> --- a/criu/files.c
> +++ b/criu/files.c
> @@ -964,6 +964,7 @@ int send_fd_to_peer(int fd, struct fdinfo_list_entry *fle, int sock)
>  
>  	pr_info("\t\tWait fdinfo pid=%d fd=%d\n", fle->pid, fle->fe->fd);
>  	futex_wait_while(&fle->real_pid, 0);
> +	futex_wait_while(&pstree_item_by_virt(fle->pid)->task_st, TSK_ALLOCATED);

Isn't the wait for fle->real_pid being non zero enough?

>  	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);
> @@ -1691,6 +1692,7 @@ static int open_transport_socket(pid_t pid)
>  		return -1;
>  	}
>  	close(sock);
> +	futex_set_and_wake(&current->task_st, TFD_INSTALLED);
>  
>  	return 0;
>  }
> diff --git a/criu/include/pstree.h b/criu/include/pstree.h
> index 5768b64..b3547ca 100644
> --- a/criu/include/pstree.h
> +++ b/criu/include/pstree.h
> @@ -4,6 +4,7 @@
>  #include "common/list.h"
>  #include "pid.h"
>  #include "images/core.pb-c.h"
> +#include "lock.h"
>  
>  /*
>   * That's the init process which usually inherit
> @@ -24,6 +25,12 @@ struct pstree_item {
>  	struct pid		*threads;	/* array of threads */
>  	CoreEntry		**core;
>  	TaskKobjIdsEntry	*ids;
> +	futex_t			task_st;
> +};
> +
> +enum {
> +	TSK_ALLOCATED = 0,
> +	TFD_INSTALLED = 1 << 0,
>  };
>  
>  struct pstree_item *current;
> diff --git a/criu/pstree.c b/criu/pstree.c
> index ec1f7ee..ed7e999 100644
> --- a/criu/pstree.c
> +++ b/criu/pstree.c
> @@ -216,6 +216,7 @@ struct pstree_item *__alloc_pstree_item(bool rst)
>  	item->pid.virt = -1;
>  	item->pid.real = -1;
>  	item->born_sid = -1;
> +	futex_init(&item->task_st);
>  
>  	return item;
>  }
> 
> .
>