CVS commit: src/sys

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

Module Name:    src
Committed By:   riastradh
Date:           Mon Mar 28 12:39:29 UTC 2022

Modified Files:
        src/sys/kern: tty.c
        src/sys/sys: tty.h

Log Message:
tty(9): New ttycancel function.

This causes any current and future ttyopens to fail until ttyclose.

This is necessary for revoke to work reliably for device detach like
ucom(4) removable USB devices.  A tty driver for a removable device
needs some way to interrupt a pending .d_open so it returns promptly.
But ttyclose only interrupts ttyopen if it's already sleeping; it
won't cause a concurrent .d_open call which _will call_ but _hasn't
yet called_ ttyopen to avoid sleeping.  Using ttycancel in the tty
driver's .d_cancel makes this work.


To generate a diff of this commit:
cvs rdiff -u -r1.299 -r1.300 src/sys/kern/tty.c
cvs rdiff -u -r1.95 -r1.96 src/sys/sys/tty.h

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