usb: preserve error when doing request
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Authored by aokblast on Aug 29 2025, 5:25 PM.

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USB

Summary

Currently, USB request not distinguished different error and always return EIO.
However, some error are recoverable or ignorable in userspace.
Therefore, we preserve the meaning of different error to userspace then
allow userspace to decide how to use the return error.

For example, when host required a vendor defined descriptor but the device refused to do so. According to the XHCI protocol. it should return USB_ERR_STALLED. And this kind of error is definitely ignorable.

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rG FreeBSD src repository

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Build Status

Buildable 66712
Build 63595: arc lint + arc unit

Event Timeline

aokblast created this revision.Aug 29 2025, 5:25 PM

Herald added a subscriber: imp. · View Herald TranscriptAug 29 2025, 5:25 PM

aokblast requested review of this revision.Aug 29 2025, 5:25 PM

Harbormaster completed remote builds in B66644: Diff 161202.Aug 29 2025, 5:25 PM

aokblast added a reviewer: USB.Aug 29 2025, 5:25 PM

aokblast edited the summary of this revision. (Show Details)Aug 29 2025, 5:31 PM

Minor updates

Harbormaster completed remote builds in B66712: Diff 161288.Aug 31 2025, 11:50 AM

aokblast added a child revision: D52166: bhyve: implement single USB device passthrough support.Aug 31 2025, 11:50 AM

kevans added a subscriber: kevans.Aug 31 2025, 2:59 PM

kevans added inline comments.

lib/libusb/libusb10_io.c
505	This seems to have accidentally conflated error namespaces, which would have coincidentally worked since the values are the same here.
507	Not strictly necessary, but IMO nice to call it out as a reminder. I'd maybe pair it with an explanation at the final return down below of where you might expect `err > 0` or an assertion if that just can't happen.
lib/libusb/libusb20_ugen20.c
799	style(9)
sys/dev/usb/usb_generic.c
895	Maybe paranoid, but I'd probably recommend: MPASS(error < nitems(usb_error_to_errno);