CVS commit: src/sys/kern

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

Module Name:    src
Committed By:   riastradh
Date:           Sat Jun 12 12:14:03 UTC 2021

Modified Files:
        src/sys/kern: kern_drvctl.c

Log Message:
drvctl(4): Hold a deviter while issuing config_detach.

Otherwise another concurrent detach -- e.g., from concurrent drvctl
or from USB port disconnection -- can pull the device_t out from
under us.

XXX Need to do this for _every_ operation config_* operation on a
device_t; device_find_by_xname is just fundamentally broken because a
concurrent detach can pull the device_t rug out from under you.

We really need another mechanism for holding a weak reference to a
device, and temporarily getting a strong reference to it; abusing
deviter is a bit of a kludge, and doesn't work very well because it
doesn't properly trigger garbage collection of devices detached while
other concurrent deviters are pending.


To generate a diff of this commit:
cvs rdiff -u -r1.47 -r1.48 src/sys/kern/kern_drvctl.c

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