Re: [Xen-devel] [PATCH] xenconsoled: Remove unexpected daemonize behavior

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Nov 02, 2015 at 11:17:38AM +0000, Ross Lagerwall wrote:
> Previously, xenconsoled's daemonize function would do nothing if its
> parent process is init (as it is under systemd but not sysv init).
> This is confusing. Instead, always daemonize when asked to, but use the
> "interactive" switch when running from the systemd service.
> 
> Because a pidfile is only written when daemonizing, drop the pidfile
> parameters from the service file (systemd keeps track of the pids
> anyway).
> 
> Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
> ---
>  tools/console/daemon/utils.c                       | 4 ----
>  tools/hotplug/Linux/systemd/xenconsoled.service.in | 3 +--
>  2 files changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/tools/console/daemon/utils.c b/tools/console/daemon/utils.c
> index dbb3b12..644f6af 100644
> --- a/tools/console/daemon/utils.c
> +++ b/tools/console/daemon/utils.c
> @@ -52,10 +52,6 @@ void daemonize(const char *pidfile)
>       int i;
>       char buf[100];
>  
> -     if (getppid() == 1) {
> -             return;
> -     }
> -

Er, I never noticed this before. And code archeology doesn't tell me why
it was written like this either.

>       if ((pid = fork()) > 0) {
>               exit(0);
>       } else if (pid == -1) {
> diff --git a/tools/hotplug/Linux/systemd/xenconsoled.service.in 
> b/tools/hotplug/Linux/systemd/xenconsoled.service.in
> index cd282bf..8e333b1 100644
> --- a/tools/hotplug/Linux/systemd/xenconsoled.service.in
> +++ b/tools/hotplug/Linux/systemd/xenconsoled.service.in
> @@ -10,10 +10,9 @@ Environment=XENCONSOLED_ARGS=
>  Environment=XENCONSOLED_TRACE=none
>  Environment=XENCONSOLED_LOG_DIR=@XEN_LOG_DIR@/console
>  EnvironmentFile=@CONFIG_DIR@/@CONFIG_LEAF_DIR@/xencommons
> -PIDFile=@XEN_RUN_DIR@/xenconsoled.pid
>  ExecStartPre=/bin/grep -q control_d /proc/xen/capabilities
>  ExecStartPre=/bin/mkdir -p ${XENCONSOLED_LOG_DIR}
> -ExecStart=@sbindir@/xenconsoled --pid-file @XEN_RUN_DIR@/xenconsoled.pid 
> --log=${XENCONSOLED_TRACE} --log-dir=${XENCONSOLED_LOG_DIR} $XENCONSOLED_ARGS
> +ExecStart=@sbindir@/xenconsoled -i --log=${XENCONSOLED_TRACE} 
> --log-dir=${XENCONSOLED_LOG_DIR} $XENCONSOLED_ARGS
>  

To the best of my knowledge this seems to conform with man 7 daemon in
Linux, "New-Style Daemons" session:

"For developing a new-style daemon, none of the initialization steps
recommended for SysV daemons need to be implemented. New-style init
systems such as systemd make all of them redundant. Moreover, since some
of these steps interfere with process monitoring, file descriptor
passing and other functionality of the init system, it is recommended
not to execute them when run as new-style service."

So the use of "-i" seems justified.

I will wait for some input from Ian and Ian.

Wei.

>  [Install]
>  WantedBy=multi-user.target
> -- 
> 2.4.3

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel