Module Name: src
Committed By: riastradh
Date: Fri Oct 7 18:59:37 UTC 2022
Modified Files:
src/sys/dev: cons.c
src/sys/kern: subr_prf.c tty.c
src/sys/sys: tty.h
Log Message:
Revert "constty(4): Make MP-safe."
Something is still busted and this is interfering with the releng
amd64 testbed.
To generate a diff of this commit:
cvs rdiff -u -r1.89 -r1.90 src/sys/dev/cons.c
cvs rdiff -u -r1.192 -r1.193 src/sys/kern/subr_prf.c
cvs rdiff -u -r1.304 -r1.305 src/sys/kern/tty.c
cvs rdiff -u -r1.100 -r1.101 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/dev/cons.c
diff -u src/sys/dev/cons.c:1.89 src/sys/dev/cons.c:1.90
--- src/sys/dev/cons.c:1.89 Fri Oct 7 18:55:50 2022
+++ src/sys/dev/cons.c Fri Oct 7 18:59:37 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: cons.c,v 1.89 2022/10/07 18:55:50 riastradh Exp $ */
+/* $NetBSD: cons.c,v 1.90 2022/10/07 18:59:37 riastradh Exp $ */
/*
* Copyright (c) 1988 University of Utah.
@@ -39,7 +39,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: cons.c,v 1.89 2022/10/07 18:55:50 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: cons.c,v 1.90 2022/10/07 18:59:37 riastradh Exp $");
#include <sys/param.h>
#include <sys/proc.h>
@@ -54,8 +54,6 @@ __KERNEL_RCSID(0, "$NetBSD: cons.c,v 1.8
#include <sys/kauth.h>
#include <sys/mutex.h>
#include <sys/module.h>
-#include <sys/atomic.h>
-#include <sys/pserialize.h>
#include <dev/cons.h>
@@ -69,8 +67,7 @@ dev_type_ioctl(cnioctl);
dev_type_poll(cnpoll);
dev_type_kqfilter(cnkqfilter);
-static bool cn_redirect(dev_t *, int, int *, struct tty **);
-static void cn_release(struct tty *);
+static bool cn_redirect(dev_t *, int, int *);
const struct cdevsw cons_cdevsw = {
.d_open = cnopen,
@@ -89,7 +86,7 @@ const struct cdevsw cons_cdevsw = {
static struct kmutex cn_lock;
-struct tty *volatile constty; /* virtual console output device */
+struct tty *constty = NULL; /* virtual console output device */
struct consdev *cn_tab; /* physical console device info */
struct vnode *cn_devvp[2]; /* vnode for underlying device. */
@@ -202,7 +199,6 @@ out: mutex_exit(&cn_lock);
int
cnread(dev_t dev, struct uio *uio, int flag)
{
- struct tty *ctp = NULL;
int error;
/*
@@ -212,31 +208,25 @@ cnread(dev_t dev, struct uio *uio, int f
* input (except a shell in single-user mode, but then,
* one wouldn't TIOCCONS then).
*/
- if (!cn_redirect(&dev, 1, &error, &ctp))
+ if (!cn_redirect(&dev, 1, &error))
return error;
- error = cdev_read(dev, uio, flag);
- cn_release(ctp);
- return error;
+ return cdev_read(dev, uio, flag);
}
int
cnwrite(dev_t dev, struct uio *uio, int flag)
{
- struct tty *ctp = NULL;
int error;
/* Redirect output, if that's appropriate. */
- if (!cn_redirect(&dev, 0, &error, &ctp))
+ if (!cn_redirect(&dev, 0, &error))
return error;
- error = cdev_write(dev, uio, flag);
- cn_release(ctp);
- return error;
+ return cdev_write(dev, uio, flag);
}
int
cnioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
{
- struct tty *ctp = NULL;
int error;
error = 0;
@@ -245,41 +235,29 @@ cnioctl(dev_t dev, u_long cmd, void *dat
* Superuser can always use this to wrest control of console
* output from the "virtual" console.
*/
- if (cmd == TIOCCONS) {
- struct tty *tp;
-
- mutex_enter(&constty_lock);
- tp = atomic_load_relaxed(&constty);
- if (tp == NULL) {
- mutex_exit(&constty_lock);
- goto passthrough; /* XXX ??? */
- }
+ if (cmd == TIOCCONS && constty != NULL) {
error = kauth_authorize_device_tty(l->l_cred,
- KAUTH_DEVICE_TTY_VIRTUAL, tp);
+ KAUTH_DEVICE_TTY_VIRTUAL, constty);
if (!error)
- atomic_store_relaxed(&constty, NULL);
- mutex_exit(&constty_lock);
- return error;
+ constty = NULL;
+ return (error);
}
-passthrough:
+
/*
* Redirect the ioctl, if that's appropriate.
* Note that strange things can happen, if a program does
* ioctls on /dev/console, then the console is redirected
* out from under it.
*/
- if (!cn_redirect(&dev, 0, &error, &ctp))
+ if (!cn_redirect(&dev, 0, &error))
return error;
- error = cdev_ioctl(dev, cmd, data, flag, l);
- cn_release(ctp);
- return error;
+ return cdev_ioctl(dev, cmd, data, flag, l);
}
/*ARGSUSED*/
int
cnpoll(dev_t dev, int events, struct lwp *l)
{
- struct tty *ctp = NULL;
int error;
/*
@@ -287,18 +265,15 @@ cnpoll(dev_t dev, int events, struct lwp
* I don't want to think of the possible side effects
* of console redirection here.
*/
- if (!cn_redirect(&dev, 0, &error, &ctp))
+ if (!cn_redirect(&dev, 0, &error))
return POLLHUP;
- error = cdev_poll(dev, events, l);
- cn_release(ctp);
- return error;
+ return cdev_poll(dev, events, l);
}
/*ARGSUSED*/
int
cnkqfilter(dev_t dev, struct knote *kn)
{
- struct tty *ctp = NULL;
int error;
/*
@@ -306,11 +281,9 @@ cnkqfilter(dev_t dev, struct knote *kn)
* I don't want to think of the possible side effects
* of console redirection here.
*/
- if (!cn_redirect(&dev, 0, &error, &ctp))
+ if (!cn_redirect(&dev, 0, &error))
return error;
- error = cdev_kqfilter(dev, kn);
- cn_release(ctp);
- return error;
+ return cdev_kqfilter(dev, kn);
}
int
@@ -456,44 +429,28 @@ cnhalt(void)
/*
* Redirect output, if that's appropriate. If there's no real console,
* return ENXIO.
+ *
+ * Call with tty_mutex held.
*/
static bool
-cn_redirect(dev_t *devp, int is_read, int *error, struct tty **ctpp)
+cn_redirect(dev_t *devp, int is_read, int *error)
{
dev_t dev = *devp;
- struct tty *ctp;
- int s;
- bool ok = false;
*error = ENXIO;
- *ctpp = NULL;
- s = pserialize_read_enter();
- if ((ctp = atomic_load_consume(&constty)) != NULL && minor(dev) == 0 &&
+ if (constty != NULL && minor(dev) == 0 &&
(cn_tab == NULL || (cn_tab->cn_pri != CN_REMOTE))) {
if (is_read) {
*error = 0;
- goto out;
+ return false;
}
- tty_acquire(ctp);
- *ctpp = ctp;
- dev = ctp->t_dev;
+ dev = constty->t_dev;
} else if (cn_tab == NULL)
- goto out;
+ return false;
else
dev = cn_tab->cn_dev;
- ok = true;
*devp = dev;
-out: pserialize_read_exit(s);
- return ok;
-}
-
-static void
-cn_release(struct tty *ctp)
-{
-
- if (ctp == NULL)
- return;
- tty_release(ctp);
+ return true;
}
MODULE(MODULE_CLASS_DRIVER, cons, NULL);
Index: src/sys/kern/subr_prf.c
diff -u src/sys/kern/subr_prf.c:1.192 src/sys/kern/subr_prf.c:1.193
--- src/sys/kern/subr_prf.c:1.192 Thu Oct 6 19:58:41 2022
+++ src/sys/kern/subr_prf.c Fri Oct 7 18:59:37 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: subr_prf.c,v 1.192 2022/10/06 19:58:41 riastradh Exp $ */
+/* $NetBSD: subr_prf.c,v 1.193 2022/10/07 18:59:37 riastradh Exp $ */
/*-
* Copyright (c) 1986, 1988, 1991, 1993
@@ -37,7 +37,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_prf.c,v 1.192 2022/10/06 19:58:41 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_prf.c,v 1.193 2022/10/07 18:59:37 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_ddb.h"
@@ -103,6 +103,7 @@ static void kprintf_internal(const char
* globals
*/
+extern struct tty *constty; /* pointer to console "window" tty */
extern int log_open; /* subr_log: is /dev/klog open? */
const char *panicstr; /* arg to first call to panic (used as a flag
to indicate that panic has already been called). */
@@ -400,35 +401,22 @@ addlog(const char *fmt, ...)
static void
putone(int c, int flags, struct tty *tp)
{
- struct tty *ctp;
- int s;
-
- /*
- * Ensure whatever constty points to can't go away while we're
- * trying to use it.
- */
- s = pserialize_read_enter();
-
if (panicstr)
- atomic_store_relaxed(&constty, NULL);
+ constty = NULL;
- if ((flags & TOCONS) &&
- (ctp = atomic_load_consume(&constty)) != NULL &&
- tp == NULL) {
- tp = ctp;
+ if ((flags & TOCONS) && tp == NULL && constty) {
+ tp = constty;
flags |= TOTTY;
}
if ((flags & TOTTY) && tp &&
tputchar(c, flags, tp) < 0 &&
- (flags & TOCONS))
- atomic_cas_ptr(&constty, tp, NULL);
+ (flags & TOCONS) && tp == constty)
+ constty = NULL;
if ((flags & TOLOG) &&
c != '\0' && c != '\r' && c != 0177)
logputchar(c);
- if ((flags & TOCONS) && ctp == NULL && c != '\0')
+ if ((flags & TOCONS) && constty == NULL && c != '\0')
(*v_putc)(c);
-
- pserialize_read_exit(s);
}
static void
Index: src/sys/kern/tty.c
diff -u src/sys/kern/tty.c:1.304 src/sys/kern/tty.c:1.305
--- src/sys/kern/tty.c:1.304 Thu Oct 6 19:58:41 2022
+++ src/sys/kern/tty.c Fri Oct 7 18:59:37 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: tty.c,v 1.304 2022/10/06 19:58:41 riastradh Exp $ */
+/* $NetBSD: tty.c,v 1.305 2022/10/07 18:59:37 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 1.304 2022/10/06 19:58:41 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tty.c,v 1.305 2022/10/07 18:59:37 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_compat_netbsd.h"
@@ -99,9 +99,6 @@ __KERNEL_RCSID(0, "$NetBSD: tty.c,v 1.30
#include <sys/module.h>
#include <sys/bitops.h>
#include <sys/compat_stub.h>
-#include <sys/atomic.h>
-#include <sys/condvar.h>
-#include <sys/pserialize.h>
#ifdef COMPAT_60
#include <compat/sys/ttycom.h>
@@ -212,9 +209,6 @@ static void *tty_sigsih;
struct ttylist_head ttylist = TAILQ_HEAD_INITIALIZER(ttylist);
int tty_count;
kmutex_t tty_lock;
-kmutex_t constty_lock;
-static struct pserialize *constty_psz;
-static kcondvar_t ttyref_cv;
struct ptm_pty *ptm = NULL;
@@ -448,29 +442,14 @@ ttycancel(struct tty *tp)
int
ttyclose(struct tty *tp)
{
+ extern struct tty *constty; /* Temporary virtual console. */
struct session *sess;
- /*
- * Make sure this is not the constty. Without constty_lock it
- * is always allowed to transition from nonnull to null.
- */
- (void)atomic_cas_ptr(&constty, tp, NULL);
-
- /*
- * We don't know if this has _ever_ been the constty: another
- * thread may have kicked it out as constty before we started
- * to close.
- *
- * So we wait for all users that might be acquiring references
- * to finish doing so -- after that, no more references can be
- * made, at which point we can safely flush the tty, wait for
- * the existing references to drain, and finally free or reuse
- * the tty.
- */
- pserialize_perform(constty_psz);
-
mutex_spin_enter(&tty_lock);
+ if (constty == tp)
+ constty = NULL;
+
ttyflush(tp, FREAD | FWRITE);
tp->t_gen++;
@@ -479,9 +458,6 @@ ttyclose(struct tty *tp)
sess = tp->t_session;
tp->t_session = NULL;
- while (tp->t_refcnt)
- cv_wait(&ttyref_cv, &tty_lock);
-
mutex_spin_exit(&tty_lock);
if (sess != NULL) {
@@ -498,44 +474,6 @@ ttyclose(struct tty *tp)
}
/*
- * tty_acquire(tp), tty_release(tp)
- *
- * Acquire a reference to tp that prevents it from being closed
- * until released. Caller must guarantee tp has not yet been
- * closed, e.g. by obtaining tp from constty during a pserialize
- * read section. Caller must not hold tty_lock.
- */
-void
-tty_acquire(struct tty *tp)
-{
- unsigned refcnt __diagused;
-
- refcnt = atomic_inc_uint_nv(&tp->t_refcnt);
- KASSERT(refcnt < UINT_MAX);
-}
-
-void
-tty_release(struct tty *tp)
-{
- unsigned old, new;
-
- KDASSERT(mutex_ownable(&tty_lock));
-
- do {
- old = atomic_load_relaxed(&tp->t_refcnt);
- if (old == 1) {
- mutex_spin_enter(&tty_lock);
- if (atomic_dec_uint_nv(&tp->t_refcnt) == 0)
- cv_broadcast(&ttyref_cv);
- mutex_spin_exit(&tty_lock);
- return;
- }
- KASSERT(old != 0);
- new = old - 1;
- } while (atomic_cas_uint(&tp->t_refcnt, old, new) != old);
-}
-
-/*
* This macro is used in canonical mode input processing, where a read
* request shall not return unless a 'line delimiter' ('\n') or 'break'
* (EOF, EOL, EOL2) character (or a signal) has been received. As EOL2
@@ -1003,6 +941,7 @@ ttyoutput(int c, struct tty *tp)
int
ttioctl(struct tty *tp, u_long cmd, void *data, int flag, struct lwp *l)
{
+ extern struct tty *constty; /* Temporary virtual console. */
struct proc *p;
struct linesw *lp;
int s, error;
@@ -1105,47 +1044,32 @@ ttioctl(struct tty *tp, u_long cmd, void
mutex_spin_exit(&tty_lock);
break;
}
- case TIOCCONS: { /* become virtual console */
- struct tty *ctp;
-
- mutex_enter(&constty_lock);
- error = 0;
- ctp = atomic_load_relaxed(&constty);
+ case TIOCCONS: /* become virtual console */
if (*(int *)data) {
- if (ctp != NULL && ctp != tp &&
- ISSET(ctp->t_state, TS_CARR_ON | TS_ISOPEN) ==
- (TS_CARR_ON | TS_ISOPEN)) {
- error = EBUSY;
- goto unlock_constty;
- }
+ if (constty && constty != tp &&
+ ISSET(constty->t_state, TS_CARR_ON | TS_ISOPEN) ==
+ (TS_CARR_ON | TS_ISOPEN))
+ return EBUSY;
pb = pathbuf_create("/dev/console");
if (pb == NULL) {
- error = ENOMEM;
- goto unlock_constty;
+ return ENOMEM;
}
NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, pb);
if ((error = namei(&nd)) != 0) {
pathbuf_destroy(pb);
- goto unlock_constty;
+ return error;
}
error = VOP_ACCESS(nd.ni_vp, VREAD, l->l_cred);
vput(nd.ni_vp);
pathbuf_destroy(pb);
if (error)
- goto unlock_constty;
+ return error;
- KASSERT(atomic_load_relaxed(&constty) == ctp ||
- atomic_load_relaxed(&constty) == NULL);
- atomic_store_release(&constty, tp);
- } else if (tp == ctp) {
- atomic_store_relaxed(&constty, NULL);
- }
-unlock_constty: mutex_exit(&constty_lock);
- if (error)
- return error;
+ constty = tp;
+ } else if (tp == constty)
+ constty = NULL;
break;
- }
case TIOCDRAIN: /* wait till output drained */
if ((error = ttywait(tp)) != 0)
return (error);
@@ -3044,8 +2968,6 @@ tty_init(void)
{
mutex_init(&tty_lock, MUTEX_DEFAULT, IPL_VM);
- mutex_init(&constty_lock, MUTEX_DEFAULT, IPL_NONE);
- constty_psz = pserialize_create();
tty_sigsih = softint_establish(SOFTINT_CLOCK, ttysigintr, NULL);
KASSERT(tty_sigsih != NULL);
Index: src/sys/sys/tty.h
diff -u src/sys/sys/tty.h:1.100 src/sys/sys/tty.h:1.101
--- src/sys/sys/tty.h:1.100 Thu Oct 6 19:58:41 2022
+++ src/sys/sys/tty.h Fri Oct 7 18:59:37 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: tty.h,v 1.100 2022/10/06 19:58:41 riastradh Exp $ */
+/* $NetBSD: tty.h,v 1.101 2022/10/07 18:59:37 riastradh Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -149,7 +149,6 @@ struct tty {
int t_sigcount; /* # pending signals */
TAILQ_ENTRY(tty) t_sigqueue; /* entry on pending signal list */
void *t_softc; /* pointer to driver's softc. */
- volatile unsigned t_refcnt; /* reference count for constty */
};
#ifdef TTY_ALLOW_PRIVATE
@@ -253,8 +252,6 @@ TAILQ_HEAD(ttylist_head, tty); /* the t
#ifdef _KERNEL
extern kmutex_t tty_lock;
-extern kmutex_t constty_lock;
-extern struct tty *volatile constty;
extern int tty_count; /* number of ttys in global ttylist */
extern struct ttychars ttydefaults;
@@ -316,8 +313,6 @@ void tty_free(struct tty *);
u_char *firstc(struct clist *, int *);
bool ttypull(struct tty *);
int tty_unit(dev_t);
-void tty_acquire(struct tty *);
-void tty_release(struct tty *);
int clalloc(struct clist *, int, int);
void clfree(struct clist *);
