[PATCH 3/3] systemd-logind: Monitor systemd-logind going away

[Peter Hutterer]

On Mon, Mar 24, 2014 at 04:32:01PM +0100, Hans de Goede wrote:
> When we're using server managed-fds through systemd-logind, systemd-logind
> *must* keep running while we are using it, as it does things like drmSetMaster
> and drmDropMaster for us on vt-switch.
> 
> On a systemd-logind restart, we cannot simply re-connect since we will then
> get a different fd for the /dev/dri/card# node, and we've tied a lot of
> state to the old fd. I've discussed this with the systemd people, and in the
> future there me be a restart mechanism were systemd-logind passed fds from
> the old logind to the new logind. But for now there answer is simply:
> "Don't restart systemd-logind", and there never really is a good reason to
> restart it.
> 
> So to ensure unpleasentness if people do decide to restart systemd-logind
> anyways (or when it crashes), monitor logind going away and make this a fatal
> error. This avoids getting a hard-hung machine on the next vt-switch and will
> hopefully quickly educate users to not restart systemd-logind while they have
> an X session using it active.
> 
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>

I've merged this one and 1/3, please send me an updated 2/3 and I'll merge
and send it to keith once I have it. Thanks.

Cheers,
   Peter

> ---
>  hw/xfree86/os-support/linux/systemd-logind.c | 34 ++++++++++++++++++++++++++--
>  1 file changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/xfree86/os-support/linux/systemd-logind.c b/hw/xfree86/os-support/linux/systemd-logind.c
> index 62858b0..d11519b 100644
> --- a/hw/xfree86/os-support/linux/systemd-logind.c
> +++ b/hw/xfree86/os-support/linux/systemd-logind.c
> @@ -310,10 +310,31 @@ message_filter(DBusConnection * connection, DBusMessage * message, void *data)
>      dbus_int32_t major, minor;
>      char *pause_str;
>  
> -    if (strcmp(dbus_message_get_path(message), info->session) != 0)
> +    dbus_error_init(&error);
> +
> +    if (dbus_message_is_signal(message,
> +                               "org.freedesktop.DBus", "NameOwnerChanged")) {
> +        char *name, *old_owner, *new_owner;
> +
> +        dbus_message_get_args(message, &error,
> +                              DBUS_TYPE_STRING, &name,
> +                              DBUS_TYPE_STRING, &old_owner,
> +                              DBUS_TYPE_STRING, &new_owner, DBUS_TYPE_INVALID);
> +        if (dbus_error_is_set(&error)) {
> +            LogMessage(X_ERROR, "systemd-logind: NameOwnerChanged: %s\n",
> +                       error.message);
> +            dbus_error_free(&error);
> +            return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
> +        }
> +
> +        if (name && strcmp(name, "org.freedesktop.login1") == 0)
> +            FatalError("systemd-logind disappeared (stopped / restarted?)\n");
> +
>          return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
> +    }
>  
> -    dbus_error_init(&error);
> +    if (strcmp(dbus_message_get_path(message), info->session) != 0)
> +        return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
>  
>      if (dbus_message_is_signal(message, "org.freedesktop.login1.Session",
>                                 "PauseDevice")) {
> @@ -472,6 +493,15 @@ connect_hook(DBusConnection *connection, void *data)
>          goto cleanup;
>      }
>  
> +    dbus_bus_add_match(connection,
> +        "type='signal',sender='org.freedesktop.DBus',interface='org.freedesktop.DBus',member='NameOwnerChanged',path='/org/freedesktop/DBus'",
> +        &error);
> +    if (dbus_error_is_set(&error)) {
> +        LogMessage(X_ERROR, "systemd-logind: could not add match: %s\n",
> +                   error.message);
> +        goto cleanup;
> +    }
> +
>      /*
>       * HdG: This is not useful with systemd <= 208 since the signal only
>       * contains invalidated property names there, rather than property, val
> -- 
> 1.9.0
> 
> _______________________________________________
> xorg-devel at lists.x.org: X.Org development
> Archives: http://lists.x.org/archives/xorg-devel
> Info: http://lists.x.org/mailman/listinfo/xorg-devel
>