Re: [Xen-devel] [PATCH 2/6] libxl: Remove linux udev rules

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Jul 06, 2015 at 11:51:39AM +0100, George Dunlap wrote:
> They are no longer needed, having been replaced by a daemon for
> driverdomains which will run scripts as necessary.
> 
> Worse yet, they seem to be broken for script-based block devices, such
> as block-iscsi.  This wouldn't matter so much if they were never run
> by default; but if you run block-attach without having created a
> domain, then the appropriate node to disable running udev scripts will
> not have been written yet, and the attach will silently fail.
> 
> Rather than try to sort out that issue, just remove them entirely.
> 
> Note: This changes tools/configure.ac, so autogen.sh may need to be
> re-run.
> 
> Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>

Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>

> ---
> CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
> CC: Ian Jackson <ian.jackson@xxxxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> CC: Roger Pau Monne <roger.pau@xxxxxxxxxx>
> 
> There was some concern that old udev scripts may end up lying around
> in /etc which will still trigger and run unless libxl/disable_udev
> exists.
> 

It's certainly not making things worse, right?

I think it's user's responsibility to make sure the installation is
clean. It's the same as he / she should avoid having stale libraries
around.

> If that's a concern, then for one release we might consider writing
> libxl/disable_udev manually in xencommons or something to make sure
> that they don't trigger.
> ---
>  tools/configure                              | 13 ++++++-------
[...]
>      }
>      libxl_vminfo_list_free(vm_list, nb_vm);
> -    int hotplug_setting = libxl__hotplug_settings(gc, t);
> -    if (hotplug_setting < 0) {
> -        LOG(ERROR, "unable to get current hotplug scripts execution 
> setting");
> -        rc = ERROR_FAIL;
> -        goto out;
> -    }
> -    if (libxl_defbool_val(info->run_hotplug_scripts) != hotplug_setting &&
> -        (nb_vm - 1)) {
> -        LOG(ERROR, "cannot change hotplug execution option once set, "
> -                    "please shutdown all guests before changing it");
> -        rc = ERROR_FAIL;
> -        goto out;
> -    }
> -
> -    if (libxl_defbool_val(info->run_hotplug_scripts)) {
> -        rc = libxl__xs_write_checked(gc, t, DISABLE_UDEV_PATH, "1");
> -        if (rc) {
> -            LOGE(ERROR, "unable to write %s = 1", DISABLE_UDEV_PATH);
> -            goto out;
> -        }
> -    } else {
> -        rc = libxl__xs_rm_checked(gc, t, DISABLE_UDEV_PATH);
> -        if (rc) {
> -            LOGE(ERROR, "unable to delete %s", DISABLE_UDEV_PATH);
> -            goto out;
> -        }

Heh, looks like this is buggy as it is -- every guest shares the same
node. I.e. if a guest has run_hotplug_script in xl config file it can
overwrite that node easily.

Wei.

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