discover: Check for devices with duplicate serial properties

If we have multipath devices present in the system, we'll end up with
duplicate mounts, parse results and boot options. This change adds a
check to see if we've encountered a device with this serial number
previously.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

3 files changed, 23 insertions, 0 deletions

diff --git a/discover/device-handler.c b/discover/device-handler.c
index 95d2039..251c517 100644
--- a/discover/device-handler.c
+++ b/discover/device-handler.c
@@ -103,6 +103,12 @@ static int device_match_id(struct discover_device *dev, const char *id)
 	return !strcmp(dev->device->id, id);
 }
 
+static int device_match_serial(struct discover_device *dev, const char *serial)
+{
+	const char *val = discover_device_get_param(dev, "ID_SERIAL");
+	return val && !strcmp(val, serial);
+}
+
 static struct discover_device *device_lookup(
 		struct device_handler *device_handler,
 		int (match_fn)(struct discover_device *, const char *),
@@ -154,6 +160,13 @@ struct discover_device *device_lookup_by_id(
 	return device_lookup(device_handler, device_match_id, id);
 }
 
+struct discover_device *device_lookup_by_serial(
+		struct device_handler *device_handler,
+		const char *serial)
+{
+	return device_lookup(device_handler, device_match_serial, serial);
+}
+
 void device_handler_destroy(struct device_handler *handler)
 {
 	talloc_free(handler);
diff --git a/discover/device-handler.h b/discover/device-handler.h
index 1d78a49..854be48 100644
--- a/discover/device-handler.h
+++ b/discover/device-handler.h
@@ -108,6 +108,9 @@ struct discover_device *device_lookup_by_label(struct device_handler *handler,
 		const char *label);
 struct discover_device *device_lookup_by_id(struct device_handler *handler,
 		const char *id);
+struct discover_device *device_lookup_by_serial(
+		struct device_handler *device_handler,
+		const char *serial);
 
 void discover_device_set_param(struct discover_device *device,
 		const char *name, const char *value);
diff --git a/discover/udev.c b/discover/udev.c
index 1c5cf71..e996e22 100644
--- a/discover/udev.c
+++ b/discover/udev.c
@@ -70,6 +70,7 @@ static int udev_handle_dev_add(struct pb_udev *udev, struct udev_device *dev)
 {
 	struct discover_device *ddev;
 	const char *typestr;
+	const char *serial;
 	const char *path;
 	const char *name;
 
@@ -104,6 +105,12 @@ static int udev_handle_dev_add(struct pb_udev *udev, struct udev_device *dev)
 		return -1;
 	}
 
+	/* we may also see multipath devices; same dev nodes (hence id), but
+	 * different serial numbers */
+	serial = udev_device_get_property_value(dev, "ID_SERIAL");
+	if (serial && device_lookup_by_serial(udev->handler, serial))
+		return -1;
+
 	ddev = discover_device_create(udev->handler, name);
 
 	ddev->device_path = udev_device_get_devnode(dev);