Re: [OSS-Tools] [PATCH v4 2/3] libdt: add support for barebox, storage-by-uuid

[Michael Olbrich <m.olbrich@pengutronix.de>]

On Sun, May 15, 2022 at 10:40:55PM +0200, Roland Hieber wrote:
> On Wed, May 11, 2022 at 10:21:24AM +0200, Michael Olbrich wrote:
> > Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
> > ---
> > 
> > changes in v3:
> > uuid comparison fixed:
> >  - compare the correct uuids
> >  - don't crash when no uuid is present
> > 
> > changes in v4:
> > use strcasecmp() to make the uuid check case insensitive.
> > 
> >  src/libdt.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++----
> >  1 file changed, 69 insertions(+), 5 deletions(-)
> > 
> > diff --git a/src/libdt.c b/src/libdt.c
> > index 48c31931e8a1..4076d9a2f4a3 100644
> > --- a/src/libdt.c
> > +++ b/src/libdt.c
> > @@ -2358,6 +2358,52 @@ out:
> >  	return dev;
> >  }
> >  
> > +static struct udev_device *of_find_device_by_uuid(const char *uuid)
> > +{
> > +	struct udev *udev;
> > +	struct udev_enumerate *enumerate;
> > +	struct udev_list_entry *devices, *dev_list_entry;
> > +	int ret = 0;
> > +
> > +	udev = udev_new();
> 
> According to the udev docs, I think this should be udev_unref()ed
> somewhere, see for example in of_find_mtd_device() above.
> 
> Hmm… looking through the existing code there are more places which could
> profit from an udev_unref()…

That's not possible: The returned udev_device keeps a pointer udev but has
not refcount :-/.
So destroying the udev struct is probably not save until all udev devices
are destroyed.

> > +	if (!udev) {
> > +		  fprintf(stderr, "Can't create udev\n");
> > +		  return NULL;
> > +	}
> > +
> > +	enumerate = udev_enumerate_new(udev);
> > +	udev_enumerate_add_match_subsystem(enumerate, "block");
> > +	udev_enumerate_scan_devices(enumerate);
> > +	devices = udev_enumerate_get_list_entry(enumerate);
> > +	udev_list_entry_foreach(dev_list_entry, devices) {
> > +		const char *path, *devtype, *outpath, *dev_uuid;
> > +		struct udev_device *device;
> > +
> > +		path = udev_list_entry_get_name(dev_list_entry);
> > +		device = udev_device_new_from_syspath(udev, path);
> > +
> 
> Same for a udev_device_unref(), somewhere…?

Well, one device is returned so I could only unref those that don't match.
And the returned on leaks as well (that's not new. It already happens in
with the existing code).

And I just copied this loop form existing code and modified. So if you
really want to fix all memory leaks then that's a lot more work.
And I have neither the time to do it nor can I actually test all the other
code.

Michael

> > +		/* distinguish device (disk) from partitions */
> > +		devtype = udev_device_get_devtype(device);
> > +		if (!devtype)
> > +			continue;
> > +		if (!strcmp(devtype, "disk")) {
> > +			dev_uuid = udev_device_get_property_value(device, "ID_PART_TABLE_UUID");
> > +			if (dev_uuid && !strcasecmp(dev_uuid, uuid)) {
> > +				outpath = udev_device_get_devnode(device);
> > +				return device;
> > +			}
> > +		} else if (!strcmp(devtype, "partition")) {
> > +			dev_uuid = udev_device_get_property_value(device, "ID_PART_ENTRY_UUID");
> > +			if (dev_uuid && !strcasecmp(dev_uuid, uuid)) {
> > +				outpath = udev_device_get_devnode(device);
> > +				return device;
> > +			}
> > +		}
> > +
> > +	}
> > +	return NULL;
> > +}
> > +
> >  /*
> >   * of_get_devicepath - get information how to access device corresponding to a device_node
> >   * @partition_node:	The device_node which shall be accessed
> > @@ -2443,11 +2489,29 @@ int of_get_devicepath(struct device_node *partition_node, char **devpath, off_t
> >  	if (!strcmp(node->name, "partitions"))
> >  		node = node->parent;
> >  
> > -	dev = of_find_device_by_node_path(node->full_name);
> > -	if (!dev) {
> > -		fprintf(stderr, "%s: cannot find device from node %s\n", __func__,
> > -				node->full_name);
> > -		return -ENODEV;
> > +	if (of_device_is_compatible(node, "barebox,storage-by-uuid")) {
> > +		const char *uuid;
> > +
> > +		ret = of_property_read_string(node, "uuid", &uuid);
> > +		if (ret) {
> > +			fprintf(stderr, "%s: missing uuid property for %s\n", __func__,
> > +					node->full_name);
> > +			return -ENODEV;
> > +		}
> > +		dev = of_find_device_by_uuid(uuid);
> > +		if (!dev) {
> > +			fprintf(stderr, "%s: cannot find device for uuid %s\n", __func__,
> > +				uuid);
> > +			return -ENODEV;
> > +		}
> > +	}
> > +	else {
> > +		dev = of_find_device_by_node_path(node->full_name);
> > +		if (!dev) {
> > +			fprintf(stderr, "%s: cannot find device from node %s\n", __func__,
> > +					node->full_name);
> > +			return -ENODEV;
> > +		}
> >  	}
> >  
> >  	mtd = of_find_mtd_device(dev);
> > -- 
> > 2.30.2
> > 
> > 
> > 
> 
> -- 
> Roland Hieber, Pengutronix e.K.          | r.hieber@pengutronix.de     |
> Steuerwalder Str. 21                     | https://www.pengutronix.de/ |
> 31137 Hildesheim, Germany                | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686         | Fax:   +49-5121-206917-5555 |
> 

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |