[PATCH] cmd: usb: Prevent reset in usb tree/info command

[Xavier Drudis Ferran <xdrudis@tinet.cat>]

When DISTRO_DEFAULTS is not set, the default environment has
bootcmd=bootflow and this will cause a UCLASS_BOOTDEV device to be
added as sibling of those UCLASS_BLK devices in boot_targets, until
boot succeeds from some device. If none succeeds, and usb is in
boot_targets, and an usb storage device is plugged to some usb port at
boot time, its UCLASS_MASS_STORAGE device will have a UCLASS_BOOTDEV
device as child, besides a UCLASS_BLK child.

If once the boot fails the user enters at the U-Boot shell prompt:

usb info

or

usb tree

The code in cmd/usb.c will eventually recurse into the UCLASS_BOOTDEV
and pass a null pointer to usb_device (because it has no parent_priv_).
This causes a reset.

Fix it (twice) by checking for null parent_priv_ and adding
UCLASS_BOOTDEV to the list of ignored class ids before the recursive
call.

This prevents the current particular problem with UCLASS_BOOTDEV, even
in case it ever gets some parent_priv_ struct which is not an
usb_device, despite being the child of a usb_device->dev. And it also
prevents possible future problems if other children are added to usb
devices that don't have parent_priv_ because they are not part of the
usb tree, just abstractions of functionality (like UCLASS_BLK and
UCLASS_BOOTDEV are now).

Signed-off-by: Xavier Drudis Ferran <xdrudis@tinet.cat>
---

v2: added UCLASS_BOOTDEV check (discussion of v1 dried up without much
    evident consensus, so hopefully Simon Glass likes it better now)
    [ https://patchwork.ozlabs.org/project/uboot/patch/ZH39SVA1vbZR3+Gk@xdrudis.tinet.cat/ ]
---

Apologies to the people in Cc: for resending this. I had a typo in the
email list address.

---
 cmd/usb.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/cmd/usb.c b/cmd/usb.c
index 6193728384..23253f2223 100644
--- a/cmd/usb.c
+++ b/cmd/usb.c
@@ -421,7 +421,9 @@ static void usb_show_tree_graph(struct usb_device *dev, char *pre)
 		 * Ignore emulators and block child devices, we only want
 		 * real devices
 		 */
-		if ((device_get_uclass_id(child) != UCLASS_USB_EMUL) &&
+		if (udev &&
+		    (device_get_uclass_id(child) != UCLASS_BOOTDEV) &&
+		    (device_get_uclass_id(child) != UCLASS_USB_EMUL) &&
 		    (device_get_uclass_id(child) != UCLASS_BLK)) {
 			usb_show_tree_graph(udev, pre);
 			pre[index] = 0;
@@ -604,10 +606,12 @@ static void usb_show_info(struct usb_device *udev)
 	     child;
 	     device_find_next_child(&child)) {
 		if (device_active(child) &&
+		    (device_get_uclass_id(child) != UCLASS_BOOTDEV) &&
 		    (device_get_uclass_id(child) != UCLASS_USB_EMUL) &&
 		    (device_get_uclass_id(child) != UCLASS_BLK)) {
 			udev = dev_get_parent_priv(child);
-			usb_show_info(udev);
+			if (udev)
+				usb_show_info(udev);
 		}
 	}
 }
-- 
2.20.1