On 22.7.2022 18.38, Alexey Sheplyakov wrote:
Hello,
On Fri, Jul 22, 2022 at 05:14:14PM +0200, Greg KH wrote:
On Fri, Jul 22, 2022 at 06:17:00PM +0400, Alexey Sheplyakov wrote:
Since commit 4736ebd7fcaff1eb8481c140ba494962847d6e0a ("usb: host:
xhci-plat: omit shared hcd if either root hub has no ports")
xhci->shared_hcd can be NULL, which causes the following Oops
on reboot:
Thanks for debugging this.
But really, why is hcd NULL at all?
xhci_plat_remove does this:
396 struct usb_hcd *shared_hcd = xhci->shared_hcd;
397
398 pm_runtime_get_sync(&dev->dev);
399 xhci->xhc_state |= XHCI_STATE_REMOVING;
400
401 usb_remove_hcd(shared_hcd);
402 xhci->shared_hcd = NULL;
However with e0fe986972f5 ("usb: host: xhci-plat: prepare operation w/o
shared hcd") and 4736ebd7fcaf ("usb: host: xhci-plat: omit shared hcd
if either root hub has no ports") it's OK to have no shared hcd, and
xhci->shared_hcd is NULL in this case.
So one should check for NULL either in xhci_plat_remove (and possibly
other users of usb_remove_hcd), or in usb_remove_hcd itself.
Yes, xhci_plat_remove() should be fixed.
It really shouldn't call usb_remove_hcd(NULL), I'll write a patch for it.
No harm in checking hcd is valid in usb_remove_hcd() like this patch either.
Thanks
-Mathias
