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.
Modified files:
Index: src/sys/kern/tty.c
diff -u src/sys/kern/tty.c:1.299 src/sys/kern/tty.c:1.300
--- src/sys/kern/tty.c:1.299 Sun Dec 5 07:44:53 2021
+++ src/sys/kern/tty.c Mon Mar 28 12:39:28 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: tty.c,v 1.299 2021/12/05 07:44:53 msaitoh Exp $ */
+/* $NetBSD: tty.c,v 1.300 2022/03/28 12:39:28 riastradh Exp $ */
/*-
* Copyright (c) 2008, 2020 The NetBSD Foundation, Inc.
@@ -63,7 +63,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tty.c,v 1.299 2021/12/05 07:44:53 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tty.c,v 1.300 2022/03/28 12:39:28 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_compat_netbsd.h"
@@ -420,6 +420,21 @@ ttylopen(dev_t device, struct tty *tp)
}
/*
+ * Interrupt any pending I/O and make it fail. Used before close to
+ * interrupt pending open/read/write/&c. and make it fail promptly.
+ */
+void
+ttycancel(struct tty *tp)
+{
+
+ mutex_spin_enter(&tty_lock);
+ tp->t_state |= TS_CANCEL;
+ cv_broadcast(&tp->t_outcv);
+ cv_broadcast(&tp->t_rawcv);
+ mutex_spin_exit(&tty_lock);
+}
+
+/*
* Handle close() on a tty line: flush and set to initial state,
* bumping generation number so that pending read/write calls
* can detect recycling of the tty.
@@ -2750,7 +2765,9 @@ ttysleep(struct tty *tp, kcondvar_t *cv,
KASSERT(mutex_owned(&tty_lock));
gen = tp->t_gen;
- if (cv == NULL)
+ if (ISSET(tp->t_state, TS_CANCEL))
+ error = ERESTART;
+ else if (cv == NULL)
error = kpause("ttypause", catch_p, timo, &tty_lock);
else if (catch_p)
error = cv_timedwait_sig(cv, &tty_lock, timo);
Index: src/sys/sys/tty.h
diff -u src/sys/sys/tty.h:1.95 src/sys/sys/tty.h:1.96
--- src/sys/sys/tty.h:1.95 Sun Jan 27 02:08:50 2019
+++ src/sys/sys/tty.h Mon Mar 28 12:39:28 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: tty.h,v 1.95 2019/01/27 02:08:50 pgoyette Exp $ */
+/* $NetBSD: tty.h,v 1.96 2022/03/28 12:39:28 riastradh Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -207,6 +207,8 @@ struct tty {
#define TS_KERN_ONLY 0x10000 /* Device is accessible by kernel
* only, deny all userland access */
+#define TS_CANCEL 0x20000 /* I/O cancelled pending close. */
+
/* Character type information. */
#define ORDINARY 0
#define CONTROL 1
@@ -281,6 +283,7 @@ void ttwakeup(struct tty *);
int ttwrite(struct tty *, struct uio *, int);
void ttychars(struct tty *);
int ttycheckoutq(struct tty *, int);
+void ttycancel(struct tty *);
int ttyclose(struct tty *);
void ttyflush(struct tty *, int);
void ttygetinfo(struct tty *, int, char *, size_t);
