[PATCH] usb: Clarify expected behavior of dev_bin_attrs_are_visible()

[Elbert Mai <code@elbertmai.com>]

The commit "usb: Export BOS descriptor to sysfs" added a binary attribute
group to sysfs. It doesn't check if the descriptors attribute should be
visible, which is by design and not an oversight. Update a comment so that
it better explains this in the dev_bin_attrs_are_visible() function.

Signed-off-by: Elbert Mai <code@elbertmai.com>
---
I had mistakenly written the entry as if it went into stable/sysfs-bus-usb
instead of testing/sysfs-bus-usb, so the "..." shouldn't be there. I see
you have already moved and corrected the bos_descriptors documentation, so
it should be all OK now.

 drivers/usb/core/sysfs.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index 777526f59720..f98263e21c2a 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -929,8 +929,11 @@ static umode_t dev_bin_attrs_are_visible(struct kobject *kobj,
 	struct device *dev = kobj_to_dev(kobj);
 	struct usb_device *udev = to_usb_device(dev);
 
-	/* All USB devices have a device descriptor, so the descriptors
-	 * attribute always exists. No need to check for its visibility.
+	/*
+	 * There's no need to check if the descriptors attribute should
+	 * be visible because all devices have a device descriptor. The
+	 * bos_descriptors attribute should be visible if and only if
+	 * the device has a BOS, so check if it exists here.
 	 */
 	if (a == &bin_attr_bos_descriptors) {
 		if (udev->bos == NULL)
-- 
2.34.1