Messages in this thread | | | Date | Fri, 28 Jan 2022 11:48:34 +0800 | Subject | Re: [PATCH -next] xhci: fix two places when dealing with return value of function xhci_check_args | From | 谢泓宇 <> |
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Hi Mathias,
On 2022/1/27 17:43, Mathias Nyman wrote: > On 26.1.2022 14.49, Hongyu Xie wrote: > >>> Anyway, why is this unique to this one driver? Why does it not show up >>> for any other driver? >> The whole thing is not about a particular driver. The thing is xhci_urb_enqueue shouldn't change the return value of xhci_check_args from -ENODEV to -EINVAL. Many other drivers only check if the return value of xchi_check_args is <= 0. > Agree, lets return -ENODEV when appropriate. > >>>> The whole point is, if xhci_check_args returns value A, xhci_urb_enqueque >>>> shouldn't return any >>>> other value, because that will change some driver's behavior(like r8152.c). >>> But you are changing how the code currently works. Are you sure you >>> want to have this "succeed" if this is on a root hub? >> Yes, I'm changing how the code currently works but not on a root hub. >>>> 2."So if 0 is returned, you will now return that here, is that ok? >>>> That is a change in functionality. >>>> But this can only ever be the case for a root hub, is that ok?" >>>> >>>> It's the same logic, but now xhci_urb_enqueue can return -ENODEV if xHC is >>>> halted. >>>> If it happens on a root hub, xhci_urb_enqueue won't be called. >>>> >>>> 3."Again, this means all is good? Why is this being called for a root hub?" >>>> >>>> It is the same logic with the old one, but now xhci_check_streams_endpoint >>>> can return -ENODEV if xHC is halted. >>> This still feels wrong to me, but I'll let the maintainer decide, as I >>> don't understand why a root hub is special here. >> Thanks please. usb_submit_urb will call usb_hcd_submit_urb. And usb_hcd_submit_urb will call rh_urb_enqueue if it's on a root hub instead of calling hcd->driver->urb_enqueue(which is xhci_urb_enqueue in this case). > xhci_urb_enqueue() shouldn't be called for roothub urbs, but if it is then we > should continue to return -EINVAL
xhci_urb_enqueue() won't be called for roothub urbs, only for none roothub urbs(see usb_hcd_submit_urb()).
So xhci_urb_enqueue() will not get 0 from xhci_check_args().
Still return -EINVAL if xhci_check_args() returns 0 in xhci_urb_enqueue()?
> > xhci_check_args() should be rewritten later, but first we want a targeted fix > that can go to stable. > > Your original patch would be ok after following modification: > if (ret <= 0) > return ret ? ret : -EINVAL;
I have two questions:
1) Why return -EINVAL for roothub urbs?
2) Should I change all the return statements about xhci_check_args() in drivers/usb/host/xhci.c?
There are 6 of them.
> > Thanks > -Mathias
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