CVS commit: src/sys/dev/usb

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sun Jun 13 00:13:24 UTC 2021

Modified Files:
        src/sys/dev/usb: usb_subr.c usbdi.c usbdivar.h

Log Message:
usb(4): Tighten interface locking and pipe references.

- Just use a reference count, not a list of pipes.

- Take the reference in usbd_open_pipe*, before we even look up the
  endpoint by address; the endpoint is not stable until we hold the
  interface and prevent usbd_set_interface.

- Make opening pipes just fail if usbd_set_interface is in progress.
  => No need to block -- might block for a while, and this is
     essentially a driver error rather than a legitimate reason to
     block.
  => This should maybe be a kassert, but it's not clear that ugen(4)
     doesn't have a user-triggerable path to that kassert, so let's
     keep it as a graceful failure for now until someone can audit
     ugen(4) and make an informed decision.

- No need for a separate interface pipe lock; just use the bus lock.

This is a little bit longer than before, but makes the bracketed
nature of the references a little clearer and introduces more
kasserts to detect mistakes with internal API usage.


To generate a diff of this commit:
cvs rdiff -u -r1.260 -r1.261 src/sys/dev/usb/usb_subr.c
cvs rdiff -u -r1.215 -r1.216 src/sys/dev/usb/usbdi.c
cvs rdiff -u -r1.127 -r1.128 src/sys/dev/usb/usbdivar.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.