[lxc-devel] [PATCH 2/2] lxc-start shouldn't exit with error, if there is inherited fd's.

Greg Kurz gkurz at fr.ibm.com
Wed Aug 24 23:28:31 UTC 2011


On Wed, 2011-08-24 at 14:17 +0400, Vladimir Smirnov wrote:
> Previous patch fixed behaviour with clone, so it's now safe just to set O_CLOEXEC flag on
> all inherited fd's.
> 

The only use case I know about where a fd leak matters is
checkpoint/restart... I think the behaviour of lxc_check_inherited() is
too restrictive. It should only print a warning when it spots a fd leak
and return 0.

Cc'd Daniel and Cedric to have some more feedback on this topic.

And for you Vladimir, would this change fix your troubles ?

> Signed-off-by: Vladimir Smirnov <civil at yandex-team.ru>
> ---
>  src/lxc/start.c |   15 +++++++++++++--
>  1 files changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/src/lxc/start.c b/src/lxc/start.c
> index b8ceff6..6df70dc 100644
> --- a/src/lxc/start.c
> +++ b/src/lxc/start.c
> @@ -154,6 +154,7 @@ int lxc_check_inherited(int fd_to_ignore)
>  	while (!readdir_r(dir, &dirent, &direntp)) {
>  		char procpath[64];
>  		char path[PATH_MAX];
> +		int flags;
> 
>  		if (!direntp)
>  			break;
> @@ -174,14 +175,24 @@ int lxc_check_inherited(int fd_to_ignore)
>  		/*
>  		 * found inherited fd
>  		 */
> -		ret = -1;
> +		flags = fcntl(fd, F_GETFD);
> +		if (flags < 0) {
> +			ret = -1;
> +			ERROR("failed to get flags, fd %d on %s", fd, path);
> +		}
> +
> +		fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
> +		if (flags < 0) {
> +			ret = -1;
> +			ERROR("failed to set CLOEXEC, fd %d on %s", fd, path);
> +		}
> 
>  		snprintf(procpath, sizeof(procpath), "/proc/self/fd/%d", fd);
> 
>  		if (readlink(procpath, path, sizeof(path)) == -1)
>  			ERROR("readlink(%s) failed : %m", procpath);
>  		else
> -			ERROR("inherited fd %d on %s", fd, path);
> +			WARN("inherited fd %d on %s", fd, path);
>  	}
> 
>  	if (closedir(dir))

-- 
Gregory Kurz                                     gkurz at fr.ibm.com
Software Engineer @ IBM/Meiosys                  http://www.ibm.com
Tel +33 (0)534 638 479                           Fax +33 (0)561 400 420

"Anarchy is about taking complete responsibility for yourself."
        Alan Moore.





More information about the lxc-devel mailing list