[PATCH] 2.2.27-pre2 tty/ldisc fixes
From: Krzysztof Taraszka
Date: Mon Nov 01 2004 - 13:43:43 EST
Here is a first attempt at bringing Alan's 2.6 and Jason's 2.4 tty/ldisc fixes
to 2.2.
Need testing and feedback.
--
Krzysztof Taraszka (dzimi@xxxxxxxxxxxxx)
http://cyborg.kernel.pl/~dzimi/
http://dzimi.jogger.pl/
diff -urN linux-2.2.26.orig/drivers/char/cyclades.c linux-2.2.26/drivers/char/cyclades.c
--- linux-2.2.26.orig/drivers/char/cyclades.c 2001-11-02 17:39:06.000000000 +0100
+++ linux-2.2.26/drivers/char/cyclades.c 2004-10-25 00:41:47.000000000 +0200
@@ -1019,10 +1019,7 @@
wake_up_interruptible(&info->delta_msr_wait);
}
if (test_and_clear_bit(Cy_EVENT_WRITE_WAKEUP, &info->event)) {
- if((tty->flags & (1<< TTY_DO_WRITE_WAKEUP))
- && tty->ldisc.write_wakeup){
- (tty->ldisc.write_wakeup)(tty);
- }
+ tty_wakeup(tty);
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->poll_wait);
}
@@ -2821,6 +2818,7 @@
cy_close(struct tty_struct *tty, struct file *filp)
{
struct cyclades_port *info = (struct cyclades_port *)tty->driver_data;
+ struct tty_ldisc *ld;
unsigned long flags;
#ifdef CY_DEBUG_OTHER
@@ -2938,8 +2936,12 @@
shutdown(info);
if (tty->driver.flush_buffer)
tty->driver.flush_buffer(tty);
- if (tty->ldisc.flush_buffer)
- tty->ldisc.flush_buffer(tty);
+ ld = tty_ldisc_ref(tty);
+ if (ld) {
+ if (ld->flush_buffer)
+ ld->flush_buffer(tty);
+ tty_ldisc_deref(ld);
+ }
CY_LOCK(info, flags);
tty->closing = 0;
@@ -4701,11 +4703,9 @@
}
CY_UNLOCK(info, flags);
}
+ tty_wakeup(tty);
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->poll_wait);
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP))
- && tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
} /* cy_flush_buffer */
diff -urN linux-2.2.26.orig/drivers/char/dz.c linux-2.2.26/drivers/char/dz.c
--- linux-2.2.26.orig/drivers/char/dz.c 2001-03-25 18:31:27.000000000 +0200
+++ linux-2.2.26/drivers/char/dz.c 2004-10-31 09:32:57.000000000 +0100
@@ -1084,10 +1084,10 @@
info->event = 0;
info->tty = 0;
- if (tty->ldisc.num != ldiscs[N_TTY].num) {
+ if (tty->ldisc.num != N_TTY) {
if (tty->ldisc.close)
(tty->ldisc.close)(tty);
- tty->ldisc = ldiscs[N_TTY];
+ tty->ldisc = *(tty_ldisc_get(N_TTY));
tty->termios->c_line = N_TTY;
if (tty->ldisc.open)
(tty->ldisc.open)(tty);
diff -urN linux-2.2.26.orig/drivers/char/epca.c linux-2.2.26/drivers/char/epca.c
--- linux-2.2.26.orig/drivers/char/epca.c 2001-11-02 17:39:06.000000000 +0100
+++ linux-2.2.26/drivers/char/epca.c 2004-10-25 00:50:02.000000000 +0200
@@ -572,7 +572,8 @@
if ((ch = verifyChannel(tty)) != NULL)
{ /* Begin if ch != NULL */
-
+ struct tty_ldisc *ld;
+
save_flags(flags);
cli();
@@ -633,8 +634,12 @@
if (tty->driver.flush_buffer)
tty->driver.flush_buffer(tty);
- if (tty->ldisc.flush_buffer)
- tty->ldisc.flush_buffer(tty);
+ ld = tty_ldisc_ref(tty);
+ if (ld != NULL) {
+ if(ld->flush_buffer)
+ ld->flush_buffer(tty);
+ tty_ldisc_deref(ld);
+ }
shutdown(ch);
tty->closing = 0;
@@ -737,12 +742,20 @@
{ /* Begin if ch != NULL */
unsigned long flags;
-
+ struct tty_ldisc *ld;
+
save_flags(flags);
cli();
if (tty->driver.flush_buffer)
tty->driver.flush_buffer(tty);
+ ld = tty_ldisc_ref(tty);
+ if (ld != NULL) {
+ if (ld->flush_buffer)
+ ld->flush_buffer(tty);
+ tty_ldisc_deref(ld);
+ }
+
if (tty->ldisc.flush_buffer)
tty->ldisc.flush_buffer(tty);
@@ -1227,9 +1240,8 @@
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->poll_wait);
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) && tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
-
+ tty_wakeup(tty);
+
} /* End pc_flush_buffer */
/* ------------------ Begin pc_flush_chars ---------------------- */
@@ -2443,9 +2455,7 @@
{ /* Begin if LOWWAIT */
ch->statusflags &= ~LOWWAIT;
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
+ tty_wakeup(tty);
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->poll_wait);
} /* End if LOWWAIT */
@@ -2462,9 +2472,7 @@
{ /* Begin if EMPTYWAIT */
ch->statusflags &= ~EMPTYWAIT;
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
+ tty_wakeup(tty);
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->poll_wait);
@@ -3327,6 +3335,7 @@
tty_wait_until_sent(tty, 0);
}
else
+ /* ldisc lock already held in ioctl */
{
if (tty->ldisc.flush_buffer)
tty->ldisc.flush_buffer(tty);
diff -urN linux-2.2.26.orig/drivers/char/generic_serial.c linux-2.2.26/drivers/char/generic_serial.c
--- linux-2.2.26.orig/drivers/char/generic_serial.c 2001-03-25 18:31:27.000000000 +0200
+++ linux-2.2.26/drivers/char/generic_serial.c 2004-10-31 08:46:56.000000000 +0100
@@ -453,9 +453,7 @@
restore_flags(flags);
wake_up_interruptible(&tty->write_wait);
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
+ tty_wakeup(tty);
func_exit ();
}
@@ -595,9 +593,7 @@
if (!tty) return;
if (test_and_clear_bit(RS_EVENT_WRITE_WAKEUP, &port->event)) {
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
+ tty_wakeup(tty);
wake_up_interruptible(&tty->write_wait);
}
func_exit ();
@@ -740,8 +736,9 @@
{
unsigned long flags;
struct gs_port *port;
-
- func_enter ();
+ struct tty_ldisc *ld;
+
+ func_enter();
if (!tty) return;
@@ -818,8 +815,12 @@
if (tty->driver.flush_buffer)
tty->driver.flush_buffer(tty);
- if (tty->ldisc.flush_buffer)
- tty->ldisc.flush_buffer(tty);
+ ld = tty_ldisc_ref(tty);
+ if (ld != NULL) {
+ if (ld->flush_buffer)
+ ld->flush_buffer(tty);
+ tty_ldisc_deref(ld);
+ }
tty->closing = 0;
port->event = 0;
diff -urN linux-2.2.26.orig/drivers/char/isicom.c linux-2.2.26/drivers/char/isicom.c
--- linux-2.2.26.orig/drivers/char/isicom.c 2001-03-25 18:31:27.000000000 +0200
+++ linux-2.2.26/drivers/char/isicom.c 2004-10-31 08:56:09.000000000 +0100
@@ -621,10 +621,8 @@
if (!tty)
return;
-
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
+
+ tty_wakeup(tty);
wake_up_interruptible(&tty->write_wait);
}
@@ -1349,7 +1347,8 @@
struct isi_port * port = (struct isi_port *) tty->driver_data;
struct isi_board * card;
unsigned long flags;
-
+ struct tty_ldisc *ld;
+
#ifdef ISICOM_DEBUG
printk(KERN_DEBUG "ISICOM: Close start!!!.\n");
#endif
@@ -1417,6 +1416,12 @@
isicom_shutdown_port(port);
if (tty->driver.flush_buffer)
tty->driver.flush_buffer(tty);
+ ld = tty_ldisc_ref(tty);
+ if (ld != NULL) {
+ if (ld->flush_buffer)
+ ld->flush_buffer(tty);
+ tty_ldisc_deref(ld);
+ }
if (tty->ldisc.flush_buffer)
tty->ldisc.flush_buffer(tty);
@@ -1912,9 +1917,7 @@
spin_unlock_irqrestore(&card->card_lock, flags);
wake_up_interruptible(&tty->write_wait);
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
+ tty_wakeup(tty);
}
diff -urN linux-2.2.26.orig/drivers/char/moxa.c linux-2.2.26/drivers/char/moxa.c
--- linux-2.2.26.orig/drivers/char/moxa.c 2001-11-02 17:39:06.000000000 +0100
+++ linux-2.2.26/drivers/char/moxa.c 2004-10-31 09:02:00.000000000 +0100
@@ -616,6 +616,7 @@
{
struct moxa_str *ch;
int port;
+ struct tty_ldisc *ld;
port = PORTNO(tty);
if (port == MAX_PORTS) {
@@ -673,8 +674,13 @@
if (tty->driver.flush_buffer)
tty->driver.flush_buffer(tty);
- if (tty->ldisc.flush_buffer)
- tty->ldisc.flush_buffer(tty);
+
+ ld = tty_ldisc_ref(tty);
+ if (ld != NULL) {
+ if (ld->flush_buffer)
+ ld->flush_buffer(tty);
+ tty_ldisc_deref(ld);
+ }
tty->closing = 0;
ch->event = 0;
ch->tty = 0;
@@ -750,9 +756,7 @@
if (ch == NULL)
return;
MoxaPortFlushData(ch->port, 1);
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup) (tty);
+ tty_wakeup(tty);
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->poll_wait);
}
@@ -989,7 +993,6 @@
moxaTimer.function = moxa_poll;
moxaTimer.expires = jiffies + (HZ / 50);
moxaTimer_on = 1;
- add_timer(&moxaTimer);
return;
}
for (card = 0; card < MAX_BOARDS; card++) {
@@ -1008,9 +1011,7 @@
if (MoxaPortTxQueue(ch->port) <= WAKEUP_CHARS) {
if (!tp->stopped) {
ch->statusflags &= ~LOWWAIT;
- if ((tp->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tp->ldisc.write_wakeup)
- (tp->ldisc.write_wakeup) (tp);
+ tty_wakeup(tp);
wake_up_interruptible(&tp->write_wait);
wake_up_interruptible(&tp->poll_wait);
}
@@ -1199,9 +1200,7 @@
if (ch->tty && (ch->statusflags & EMPTYWAIT)) {
if (MoxaPortTxQueue(ch->port) == 0) {
ch->statusflags &= ~EMPTYWAIT;
- if ((ch->tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- ch->tty->ldisc.write_wakeup)
- (ch->tty->ldisc.write_wakeup) (ch->tty);
+ tty_wakeup(ch->tty);
wake_up_interruptible(&ch->tty->write_wait);
wake_up_interruptible(&ch->tty->poll_wait);
return;
diff -urN linux-2.2.26.orig/drivers/char/mxser.c linux-2.2.26/drivers/char/mxser.c
--- linux-2.2.26.orig/drivers/char/mxser.c 2001-03-25 18:31:28.000000000 +0200
+++ linux-2.2.26/drivers/char/mxser.c 2004-10-31 09:06:54.000000000 +0100
@@ -712,9 +712,7 @@
if (!tty)
return;
if (test_and_clear_bit(MXSER_EVENT_TXLOW, &info->event)) {
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup) (tty);
+ tty_wakeup(tty);
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->poll_wait);
}
@@ -796,6 +794,7 @@
struct mxser_struct *info = (struct mxser_struct *) tty->driver_data;
unsigned long flags;
unsigned long timeout;
+ struct tty_ldisc *ld;
if (PORTNO(tty) == MXSER_PORTS)
return;
@@ -876,6 +875,12 @@
mxser_shutdown(info);
if (tty->driver.flush_buffer)
tty->driver.flush_buffer(tty);
+ ld = tty_ldisc_ref(tty);
+ if (ld) {
+ if (ld->flush_buffer)
+ ld->flush_buffer(tty);
+ tty_ldisc_deref(ld);
+ }
if (tty->ldisc.flush_buffer)
tty->ldisc.flush_buffer(tty);
tty->closing = 0;
@@ -1013,9 +1018,7 @@
restore_flags(flags);
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->poll_wait);
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup) (tty);
+ tty_wakeup(tty);
}
static int mxser_ioctl(struct tty_struct *tty, struct file *file,
diff -urN linux-2.2.26.orig/drivers/char/n_tty.c linux-2.2.26/drivers/char/n_tty.c
--- linux-2.2.26.orig/drivers/char/n_tty.c 2001-03-25 18:31:25.000000000 +0200
+++ linux-2.2.26/drivers/char/n_tty.c 2004-10-31 13:27:14.177336648 +0100
@@ -78,11 +78,18 @@
spin_unlock_irqrestore(&tty->read_lock, flags);
}
-/*
+/*
+ * check_unthrottle - allow new receive data
+ * @tty; tty device
+ *
* Check whether to call the driver.unthrottle function.
* We test the TTY_THROTTLED bit first so that it always
- * indicates the current state.
- */
+ * indicates the current state. The decision about whether
+ * it is worth allowing more input has been taken by the caller.
+ * Can sleep, may be called under the atomic_read semaphore but
+ * this is not guaranteed.
+*/
+
static void check_unthrottle(struct tty_struct * tty)
{
if (tty->count &&
@@ -92,10 +99,14 @@
}
/*
+ * reset_buffer_flags - reset buffer state
+ * @tty: terminal to reset
+ *
* Reset the read buffer counters, clear the flags,
* and make sure the driver is unthrottled. Called
* from n_tty_open() and n_tty_flush_buffer().
*/
+
static void reset_buffer_flags(struct tty_struct *tty)
{
unsigned long flags;
@@ -109,8 +120,18 @@
}
/*
- * Flush the input buffer
+ * n_tty_flush_buffer - clean input queue
+ * @tty: terminal device
+ *
+ * Flush the input buffer. Called when the line discipline is
+ * being closed, when the tty layer wants the buffer flushed (eg
+ * at hangup) or when the N_TTY line discipline internally has to
+ * clean the pending queue (for example some signals).
+ *
+ * FIXME: tty->ctrl_status is not spinlocked and relies on
+ * lock_kernel() still.
*/
+
void n_tty_flush_buffer(struct tty_struct * tty)
{
/* clear everything and unthrottle the driver */
@@ -127,8 +148,13 @@
}
/*
- * Return number of characters buffered to be delivered to user
+ * n_tty_chars_in_buffer - report available bytes
+ * @tty: tty device
+ *
+ * Report the number of characters buffered to be delivered to user
+ * at this instant in time.
*/
+
ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
{
unsigned long flags;
@@ -210,9 +236,19 @@
}
/*
- * opost_block --- to speed up block console writes, among other
- * things.
+ * opost_block - block postprocess
+ * @tty: terminal device
+ * @inbuf: user buffer
+ * @nr: number of bytes
+ *
+ * This path is used to speed up block console writes, among other
+ * things when processing blocks of output data. It handles only
+ * the simple cases normally found and helps to generate blocks of
+ * symbols for the console driver and thus improve performance.
+ *
+ * Called from write_chan under the tty layer write lock.
*/
+
static ssize_t opost_block(struct tty_struct * tty,
const unsigned char * inbuf, unsigned int nr)
{
@@ -301,6 +337,16 @@
}
}
+/*
+ * eraser - handle erase function
+ * @c: character input
+ * @tty: terminal device
+ *
+ * Perform erase and neccessary output when an erase character is
+ * present in the stream from the driver layer. Handles the complexities
+ * of UTF-8 multibyte symbols.
+ */
+
static void eraser(unsigned char c, struct tty_struct *tty)
{
enum { ERASE, WERASE, KILL } kill_type;
@@ -417,6 +463,18 @@
finish_erasing(tty);
}
+/*
+ * isig - handle the ISIG optio
+ * @sig: signal
+ * @tty: terminal
+ * @flush: force flush
+ *
+ * Called when a signal is being sent due to terminal input. This
+ * may caus terminal flushing to take place according to the termios
+ * settings and character used. Called from the driver receive_buf
+ * path so serialized.
+ */
+
static inline void isig(int sig, struct tty_struct *tty, int flush)
{
if (tty->pgrp > 0)
@@ -428,6 +486,16 @@
}
}
+/*
+ * n_tty_receive_break - handle break
+ * @tty: terminal
+ *
+ * An RS232 break event has been hit in the incoming bitstream. This
+ * can cause a variety of events depending upon the termios settings.
+ *
+ * Called from the receive_buf path so single threaded.
+ */
+
static inline void n_tty_receive_break(struct tty_struct *tty)
{
if (I_IGNBRK(tty))
@@ -445,19 +513,41 @@
wake_up_interruptible(&tty->poll_wait);
}
+/*
+ * n_tty_receive_overrun - handle overrun reporting
+ * @tty: terminal
+ *
+ * Data arrived faster than we could process it. While the tty
+ * driver has flagged this the bits that were missed are gone
+ * forever.
+ *
+ * Called from the receive_buf path so single threaded. Does not
+ * need locking as num_overrun and overrun_time are function
+ * private.
+ */
+
static inline void n_tty_receive_overrun(struct tty_struct *tty)
{
char buf[64];
tty->num_overrun++;
if (time_before(tty->overrun_time, jiffies - HZ)) {
- printk("%s: %d input overrun(s)\n", tty_name(tty, buf),
+ printk(KERN_WARNING "%s: %d input overrun(s)\n", tty_name(tty, buf),
tty->num_overrun);
tty->overrun_time = jiffies;
tty->num_overrun = 0;
}
}
+/*
+ * n_tty_receive_parity_error - error notifier
+ * @tty: terminal device
+ * @c: character
+ *
+ * Process a parity error and queue the right data to indicate
+ * the error case if neccessary. Locking as per n_tty_receive_buf.
+ */
+
static inline void n_tty_receive_parity_error(struct tty_struct *tty,
unsigned char c)
{
@@ -476,6 +566,16 @@
wake_up_interruptible(&tty->poll_wait);
}
+/*
+ * n_tty_receive_char - perform processing
+ * @tty: terminal device
+ * @c: character
+ *
+ * Process an individual character of input received from the driver.
+ * This is serialized with respect to itself by the rules for the
+ * driver above.
+ */
+
static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
{
if (tty->raw) {
@@ -667,6 +767,16 @@
put_tty_queue(c, tty);
}
+/*
+ * n_tty_receive_room - receive space
+ * @tty: terminal
+ *
+ * Called by the driver to find out how much data it is
+ * permitted to feed to the line discipline without any being lost
+ * and thus to manage flow control. Not serialized. Answers for the
+ * "instant".
+ */
+
static int n_tty_receive_room(struct tty_struct *tty)
{
int left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
@@ -685,6 +795,19 @@
return 0;
}
+/*
+ * n_tty_receive_buf - data receive
+ * @tty: terminal device
+ * @cp: buffer
+ * @fp: flag buffer
+ * @count: characters
+ *
+ * Called by the terminal driver when a block of characters has
+ * been received. This function must be called from soft contexts
+ * not from interrupt context. The driver is responsible for making
+ * calls one at a time and in order (or using queue_ldisc)
+ */
+
static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
char *fp, int count)
{
@@ -770,6 +893,18 @@
current->sig->action[sig-1].sa.sa_handler == SIG_IGN);
}
+/*
+ * n_tty_set_termios - termios data changed
+ * @tty: terminal
+ * @old: previous data
+ *
+ * Called by the tty layer when the user changes termios flags so
+ * that the line discipline can plan ahead. This function cannot sleep
+ * and is protected from re-entry by the tty layer. The user is
+ * guaranteed that this function will not be re-entered or in progress
+ * when the ldisc is closed.
+ */
+
static void n_tty_set_termios(struct tty_struct *tty, struct termios * old)
{
if (!tty)
@@ -785,7 +920,6 @@
I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
I_PARMRK(tty)) {
- cli();
memset(tty->process_char_map, 0, 256/8);
if (I_IGNCR(tty) || I_ICRNL(tty))
@@ -821,7 +955,6 @@
set_bit(SUSP_CHAR(tty), &tty->process_char_map);
}
clear_bit(__DISABLED_CHAR, &tty->process_char_map);
- sti();
tty->raw = 0;
tty->real_raw = 0;
} else {
@@ -835,6 +968,16 @@
}
}
+/*
+ * n_tty_close - close the ldisc for this tty
+ * @tty: device
+ *
+ * Called from the terminal layer when this line discipline is
+ * being shut down, either because of a close or becsuse of a
+ * discipline change. The function will not be called while other
+ * ldisc methods are in progress.
+ */
+
static void n_tty_close(struct tty_struct *tty)
{
n_tty_flush_buffer(tty);
@@ -844,6 +987,16 @@
}
}
+/*
+ * n_tty_open - open an ldisc
+ * @tty: terminal to open
+ *
+ * Called when this line discipline is being attached to the
+ * terminal device. Can sleep. Called serialized so that no
+ * other events will occur in parallel. No further open will occur
+ * until a close.
+ */
+
static int n_tty_open(struct tty_struct *tty)
{
if (!tty)
@@ -876,13 +1029,22 @@
}
/*
- * Helper function to speed up read_chan. It is only called when
+ * copy_from_read_buf - copy read data directly
+ * @tty: terminal device
+ * @b: user data
+ * @nr: size of data
+ *
+ * Helper function to speed up read_chan. It is only called when
* ICANON is off; it copies characters straight from the tty queue to
- * user space directly. It can be profitably called twice; once to
+ * user space directly. It can be profitably called twice; once to
* drain the space from the tail pointer to the (physical) end of the
* buffer, and once to drain the space from the (physical) beginning of
* the buffer to head pointer.
+ *
+ * Called under the tty->atomic_read sem and with TTY_DONT_FLIP set
+ *
*/
+
static inline int copy_from_read_buf(struct tty_struct *tty,
unsigned char **b,
size_t *nr)
@@ -910,25 +1072,18 @@
return retval;
}
-static ssize_t read_chan(struct tty_struct *tty, struct file *file,
- unsigned char *buf, size_t nr)
+/**
+ * job_control - check job control
+ * @tty: tty
+ * @file: file handle
+ *
+ * Perform job control management checks on this file/tty descriptor
+ * and if appropriate send any needed signals and return a negative
+ * error code if action should be taken.
+*/
+
+static int job_control(struct tty_struct *tty, struct file *file)
{
- unsigned char *b = buf;
- struct wait_queue wait = { current, NULL };
- int c;
- int minimum, time;
- ssize_t retval = 0;
- ssize_t size;
- long timeout;
- unsigned long flags;
-
-do_it_again:
-
- if (!tty->read_buf) {
- printk("n_tty_read_chan: called with read_buf == NULL?!?\n");
- return -EIO;
- }
-
/* Job control check -- must be done at start and after
every sleep (POSIX.1 7.1.1.4). */
/* NOTE: not yet done after every sleep pending a thorough
@@ -947,7 +1102,48 @@
return -ERESTARTSYS;
}
}
+return 0;
+
+}
+
+/**
+ * read_chan - read function for tty
+ * @tty: tty device
+ * @file: file object
+ * @buf: userspace buffer pointer
+ * @nr: size of I/O
+ *
+ * Perform reads for the line discipline. We are guaranteed that the
+ * line discipline will not be closed under us but we may get multiple
+ * parallel readers and must handle this ourselves. We may also get
+ * a hangup. Always called in user context, may sleep.
+ *
+ * This code must be sure never to sleep through a hangup.
+ */
+
+static ssize_t read_chan(struct tty_struct *tty, struct file *file,
+ unsigned char *buf, size_t nr)
+{
+ unsigned char *b = buf;
+ DECLARE_WAITQUEUE(wait, current);
+ int c;
+ int minimum, time;
+ ssize_t retval = 0;
+ ssize_t size;
+ long timeout;
+ unsigned long flags;
+ do_it_again:
+
+ if (!tty->read_buf) {
+ printk("n_tty_read_chan: called with read_buf == NULL?!?\n");
+ return -EIO;
+ }
+
+ c = job_control(tty, file);
+ if(c < 0)
+ return c;
+
minimum = time = 0;
timeout = MAX_SCHEDULE_TIMEOUT;
if (!tty->icanon) {
@@ -969,6 +1165,9 @@
}
}
+ /*
+ * Internal serialization of reads.
+ */
if (file->f_flags & O_NONBLOCK) {
if (down_trylock(&tty->atomic_read))
return -EAGAIN;
@@ -1103,6 +1302,21 @@
return retval;
}
+/*
+ * write_chan - write function for tty
+ * @tty: tty device
+ * @file: file object
+ * @buf: userspace buffer pointer
+ * @nr: size of I/O
+ *
+ * Write function of the terminal device. This is serialized with
+ * respect to other write callers but not to termios changes, reads
+ * and other such events. We must be careful with N_TTY as the receive
+ * code will echo characters, thus calling driver write methods.
+ *
+ * This code must be sure never to sleep through a hangup.
+ */
+
static ssize_t write_chan(struct tty_struct * tty, struct file * file,
const unsigned char * buf, size_t nr)
{
@@ -1172,6 +1386,25 @@
return (b - buf) ? b - buf : retval;
}
+/*
+ * normal_poll - poll method for N_TTY
+ * @tty: terminal device
+ * @file: file accessing it
+ * @wait: poll table
+ *
+ * Called when the line discipline is asked to poll() for data or
+ * for special events. This code is not serialized with respect to
+ * other events save open/close.
+ *
+ * This code must be sure never to sleep through a hangup.
+ * Called without the kernel lock held - fine
+ *
+ * FIXME: if someone changes the VMIN or discipline settings for the
+ * terminal while another process is in poll() the poll does not
+ * recompute the new limits. Possibly set_termios should issue
+ * a read wakeup to fix this bug.
+ */
+
static unsigned int normal_poll(struct tty_struct * tty, struct file * file, poll_table *wait)
{
unsigned int mask = 0;
diff -urN linux-2.2.26.orig/drivers/char/pcxx.c linux-2.2.26/drivers/char/pcxx.c
--- linux-2.2.26.orig/drivers/char/pcxx.c 2001-03-25 18:31:25.000000000 +0200
+++ linux-2.2.26/drivers/char/pcxx.c 2004-10-31 09:34:16.000000000 +0100
@@ -621,10 +621,10 @@
** please send me a note. brian@xxxxxxxxx
** Don't know either what this is supposed to do clameter@xxxxxxxxxxx
*/
- if(tty->ldisc.num != ldiscs[N_TTY].num) {
+ if(tty->ldisc.num != N_TTY) {
if(tty->ldisc.close)
(tty->ldisc.close)(tty);
- tty->ldisc = ldiscs[N_TTY];
+ tty->ldisc = *(tty_ldisc_get(N_TTY));
tty->termios->c_line = N_TTY;
if(tty->ldisc.open)
(tty->ldisc.open)(tty);
diff -urN linux-2.2.26.orig/drivers/char/pty.c linux-2.2.26/drivers/char/pty.c
--- linux-2.2.26.orig/drivers/char/pty.c 2001-03-25 18:31:24.000000000 +0200
+++ linux-2.2.26/drivers/char/pty.c 2004-10-31 09:17:13.000000000 +0100
@@ -134,6 +134,10 @@
* (2) avoid redundant copying for cases where count >> receive_room
* N.B. Calls from user space may now return an error code instead of
* a count.
+ *
+ * FIXME: Our pty_write method is called with our ldisc lock held but
+ * not our partners. We can't just take the other one blindly without
+ + * risking deadlocks. There is also the small matter of TTY_DONT_FLIP
*/
static int pty_write(struct tty_struct * tty, int from_user,
const unsigned char *buf, int count)
diff -urN linux-2.2.26.orig/drivers/char/riscom8.c linux-2.2.26/drivers/char/riscom8.c
--- linux-2.2.26.orig/drivers/char/riscom8.c 2001-11-02 17:39:06.000000000 +0100
+++ linux-2.2.26/drivers/char/riscom8.c 2004-10-31 09:21:17.000000000 +0100
@@ -1110,7 +1110,8 @@
struct riscom_board *bp;
unsigned long flags;
unsigned long timeout;
-
+ struct tty_ldisc *ld;
+
if (!port || rc_paranoia_check(port, tty->device, "close"))
return;
@@ -1180,6 +1181,12 @@
rc_shutdown_port(bp, port);
if (tty->driver.flush_buffer)
tty->driver.flush_buffer(tty);
+ ld = tty_ldisc_ref(tty);
+ if (ld != NULL) {
+ if(ld->flush_buffer)
+ ld->flush_buffer(tty);
+ tty_ldisc_deref(ld);
+ }
if (tty->ldisc.flush_buffer)
tty->ldisc.flush_buffer(tty);
tty->closing = 0;
@@ -1358,9 +1365,7 @@
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->poll_wait);
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
+ tty_wakeup(tty);
}
static int rc_get_modem_info(struct riscom_port * port, unsigned int *value)
@@ -1736,9 +1741,7 @@
return;
if (test_and_clear_bit(RS_EVENT_WRITE_WAKEUP, &port->event)) {
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
+ tty_wakeup(tty);
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->poll_wait);
}
diff -urN linux-2.2.26.orig/drivers/char/selection.c linux-2.2.26/drivers/char/selection.c
--- linux-2.2.26.orig/drivers/char/selection.c 2001-03-25 18:31:25.000000000 +0200
+++ linux-2.2.26/drivers/char/selection.c 2004-10-31 09:22:38.000000000 +0100
@@ -296,9 +296,11 @@
{
struct vt_struct *vt = (struct vt_struct *) tty->driver_data;
int pasted = 0, count;
+ struct tty_ldisc *ld;
struct wait_queue wait = { current, NULL };
poke_blanked_console();
+ ld = tty_ldisc_ref_wait(tty);
add_wait_queue(&vt->paste_wait, &wait);
while (sel_buffer && sel_buffer_lth > pasted) {
current->state = TASK_INTERRUPTIBLE;
@@ -313,6 +315,8 @@
}
remove_wait_queue(&vt->paste_wait, &wait);
current->state = TASK_RUNNING;
+
+ tty_ldisc_deref(ld);
return 0;
}
diff -urN linux-2.2.26.orig/drivers/char/serial167.c linux-2.2.26/drivers/char/serial167.c
--- linux-2.2.26.orig/drivers/char/serial167.c 2001-03-25 18:31:26.000000000 +0200
+++ linux-2.2.26/drivers/char/serial167.c 2004-10-31 09:36:07.000000000 +0100
@@ -1943,10 +1943,10 @@
tty->ldisc.flush_buffer(tty);
info->event = 0;
info->tty = 0;
- if (tty->ldisc.num != ldiscs[N_TTY].num) {
+ if (tty->ldisc.num != N_TTY) {
if (tty->ldisc.close)
(tty->ldisc.close)(tty);
- tty->ldisc = ldiscs[N_TTY];
+ tty->ldisc = *(tty_ldisc_get(N_TTY));
tty->termios->c_line = N_TTY;
if (tty->ldisc.open)
(tty->ldisc.open)(tty);
diff -urN linux-2.2.26.orig/drivers/char/synclink.c linux-2.2.26/drivers/char/synclink.c
--- linux-2.2.26.orig/drivers/char/synclink.c 2001-11-02 17:39:06.000000000 +0100
+++ linux-2.2.26/drivers/char/synclink.c 2004-10-31 09:30:48.000000000 +0100
@@ -990,6 +990,42 @@
return 0;
}
+/**
+ * line discipline callback wrappers
+ *
+ * The wrappers maintain line discipline references
+ * while calling into the line discipline.
+ *
+ * ldisc_flush_buffer - flush line discipline receive buffers
+ * ldisc_receive_buf - pass receive data to line discipline
+ */
+
+static void ldisc_flush_buffer(struct tty_struct *tty)
+{
+ struct tty_ldisc *ld = tty_ldisc_ref(tty);
+
+ if (ld) {
+ if (ld->flush_buffer)
+ ld->flush_buffer(tty);
+ tty_ldisc_deref(ld);
+ }
+}
+
+static void ldisc_receive_buf(struct tty_struct *tty,
+ const __u8 *data, char *flags, int count)
+{
+ struct tty_ldisc *ld;
+
+ if (!tty)
+ return;
+ ld = tty_ldisc_ref(tty);
+ if (ld) {
+ if (ld->receive_buf)
+ ld->receive_buf(tty, data, flags, count);
+ tty_ldisc_deref(ld);
+ }
+}
+
/* mgsl_stop() throttle (stop) transmitter
*
* Arguments: tty pointer to tty info structure
@@ -1141,13 +1177,7 @@
__FILE__,__LINE__,info->device_name);
if (tty) {
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tty->ldisc.write_wakeup) {
- if ( debug_level >= DEBUG_LEVEL_BH )
- printk( "%s(%d):calling ldisc.write_wakeup on %s\n",
- __FILE__,__LINE__,info->device_name);
- (tty->ldisc.write_wakeup)(tty);
- }
+ tty_wakeup(tty);
wake_up_interruptible(&tty->write_wait);
}
@@ -2392,11 +2422,8 @@
spin_unlock_irqrestore(&info->irq_spinlock,flags);
wake_up_interruptible(&tty->write_wait);
- if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
-
-} /* end of mgsl_flush_buffer() */
+ tty_wakeup(tty);
+}
/* mgsl_send_xchar()
*
@@ -3297,10 +3324,8 @@
if (tty->driver.flush_buffer)
tty->driver.flush_buffer(tty);
-
- if (tty->ldisc.flush_buffer)
- tty->ldisc.flush_buffer(tty);
-
+
+ ldisc_flush_buffer(tty);
shutdown(info);
tty->closing = 0;
@@ -6999,11 +7024,7 @@
}
else
#endif
- {
- /* Call the line discipline receive callback directly. */
- if ( tty && tty->ldisc.receive_buf )
- tty->ldisc.receive_buf(tty, info->intermediate_rxbuffer, info->flag_buf, framesize);
- }
+ ldisc_receive_buf(tty, info->intermediate_rxbuffer, info->flag_buf, framesize);
}
}
/* Free the buffers used by this frame. */
@@ -7175,9 +7196,7 @@
memcpy( info->intermediate_rxbuffer, pBufEntry->virt_addr, framesize);
info->icount.rxok++;
- /* Call the line discipline receive callback directly. */
- if ( tty && tty->ldisc.receive_buf )
- tty->ldisc.receive_buf(tty, info->intermediate_rxbuffer, info->flag_buf, framesize);
+ ldisc_receive_buf(tty, info->intermediate_rxbuffer, info->flag_buf, framesize);
}
/* Free the buffers used by this frame. */
diff -urN linux-2.2.26.orig/drivers/char/tty_io.c linux-2.2.26/drivers/char/tty_io.c
--- linux-2.2.26.orig/drivers/char/tty_io.c 2004-10-31 11:15:19.128606952 +0100
+++ linux-2.2.26/drivers/char/tty_io.c 2004-10-31 12:02:45.000000000 +0100
@@ -101,9 +101,13 @@
#define TTY_PARANOIA_CHECK 1
#define CHECK_TTY_COUNT 1
+#define __builtin_expect(x, expected_value) (x)
+#define likely(x) __builtin_expect((x),1)
+
+/* Lock for tty_termios changes - private to tty_io/tty_ioctl */
+spinlock_t tty_termios_lock = SPIN_LOCK_UNLOCKED;
struct termios tty_std_termios; /* for the benefit of tty drivers */
struct tty_driver *tty_drivers = NULL; /* linked list of tty drivers */
-struct tty_ldisc ldiscs[NR_LDISCS]; /* line disc dispatch table */
#ifdef CONFIG_UNIX98_PTYS
extern struct tty_driver ptm_driver[]; /* Unix98 pty masters; for /dev/ptmx */
@@ -204,44 +208,256 @@
return 0;
}
+/*
+ * This is probably overkill for real world processors but
+ * they are not on hot paths so a little discipline won't do
+ * any harm.
+ */
+
+static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
+{
+ unsigned long flags;
+ spin_lock_irqsave(&tty_termios_lock, flags);
+ tty->termios->c_line = num;
+ spin_unlock_irqrestore(&tty_termios_lock, flags);
+}
+
+/*
+ * This guards the refcounted line discipline lists. The lock
+ * must be taken with irqs off because there are hangup path
+ * callers who will do ldisc lookups and cannot sleep.
+ */
+
+spinlock_t tty_ldisc_lock = SPIN_LOCK_UNLOCKED;
+DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait);
+struct tty_ldisc tty_ldiscs[NR_LDISCS]; /* line disc dispatch table */
+
int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
{
+
+ unsigned long flags;
+ int ret = 0;
+
if (disc < N_TTY || disc >= NR_LDISCS)
return -EINVAL;
-
+
+ spin_lock_irqsave(&tty_ldisc_lock, flags);
if (new_ldisc) {
- ldiscs[disc] = *new_ldisc;
- ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
- ldiscs[disc].num = disc;
- } else
- memset(&ldiscs[disc], 0, sizeof(struct tty_ldisc));
+ tty_ldiscs[disc] = *new_ldisc;
+ tty_ldiscs[disc].num = disc;
+ tty_ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
+ tty_ldiscs[disc].refcount = 0;
+ } else {
+ if(tty_ldiscs[disc].refcount)
+ ret = -EBUSY;
+ else
+ tty_ldiscs[disc].flags &= ~LDISC_FLAG_DEFINED;
+ }
+ spin_unlock_irqrestore(&tty_ldisc_lock, flags);
- return 0;
+ return ret;
}
-/* Set the discipline of a tty line. */
+EXPORT_SYMBOL(tty_register_ldisc);
+
+struct tty_ldisc *tty_ldisc_get(int disc)
+{
+ unsigned long flags;
+ struct tty_ldisc *ld;
+
+ if (disc < N_TTY || disc >= NR_LDISCS)
+ return NULL;
+
+ spin_lock_irqsave(&tty_ldisc_lock, flags);
+
+ ld = &tty_ldiscs[disc];
+ /* Check the entry is defined */
+ if(ld->flags & LDISC_FLAG_DEFINED)
+ ld->refcount++;
+ else
+ ld = NULL;
+ spin_unlock_irqrestore(&tty_ldisc_lock, flags);
+ return ld;
+}
+
+EXPORT_SYMBOL_GPL(tty_ldisc_get);
+
+void tty_ldisc_put(int disc)
+{
+ struct tty_ldisc *ld;
+ unsigned long flags;
+
+ if (disc < N_TTY || disc >= NR_LDISCS)
+ BUG();
+
+ spin_lock_irqsave(&tty_ldisc_lock, flags);
+ ld = &tty_ldiscs[disc];
+ if(ld->refcount <= 0)
+ BUG();
+ ld->refcount--;
+ spin_unlock_irqrestore(&tty_ldisc_lock, flags);
+}
+
+EXPORT_SYMBOL_GPL(tty_ldisc_put);
+
+void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld)
+{
+ tty->ldisc = *ld;
+ tty->ldisc.refcount = 0;
+}
+
+/**
+ * tty_ldisc_try - internal helper
+ * @tty: the tty
+ *
+ * Make a single attempt to grab and bump the refcount on
+ * the tty ldisc. Return 0 on failure or 1 on success. This is
+ * used to implement both the waiting and non waiting versions
+ * of tty_ldisc_ref
+ */
+
+static int tty_ldisc_try(struct tty_struct *tty)
+{
+ unsigned long flags;
+ struct tty_ldisc *ld;
+ int ret = 0;
+
+ spin_lock_irqsave(&tty_ldisc_lock, flags);
+ ld = &tty->ldisc;
+ if(test_bit(TTY_LDISC, &tty->flags)) {
+ ld->refcount++;
+ ret = 1;
+ }
+ spin_unlock_irqrestore(&tty_ldisc_lock, flags);
+ return ret;
+}
+
+/**
+ * tty_ldisc_ref_wait - wait for the tty ldisc
+ * @tty: tty device
+ *
+ * Dereference the line discipline for the terminal and take a
+ * reference to it. If the line discipline is in flux then
+ * wait patiently until it changes.
+ *
+ * Note: Must not be called from an IRQ/timer context. The caller
+ * must also be careful not to hold other locks that will deadlock
+ * against a discipline change, such as an existing ldisc reference
+ * (which we check for)
+ */
+
+struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty)
+{
+ /* wait_event is a macro */
+ wait_event(tty_ldisc_wait, tty_ldisc_try(tty));
+ return &tty->ldisc;
+}
+
+EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait);
+
+/**
+ * tty_ldisc_ref - get the tty ldisc
+ * @tty: tty device
+ *
+ * Dereference the line discipline for the terminal and take a
+ * reference to it. If the line discipline is in flux then
+ * return NULL. Can be called from IRQ and timer functions.
+ */
+
+struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty)
+{
+ if(tty_ldisc_try(tty))
+ return &tty->ldisc;
+ return NULL;
+}
+
+EXPORT_SYMBOL_GPL(tty_ldisc_ref);
+
+void tty_ldisc_deref(struct tty_ldisc *ld)
+{
+ unsigned long flags;
+
+ if(ld == NULL)
+ BUG();
+
+ spin_lock_irqsave(&tty_ldisc_lock, flags);
+ if(ld->refcount == 0)
+ printk(KERN_EMERG "tty_ldisc_deref: no references.\n");
+ else
+ ld->refcount--;
+ if(ld->refcount == 0)
+ wake_up(&tty_ldisc_wait);
+ spin_unlock_irqrestore(&tty_ldisc_lock, flags);
+}
+
+EXPORT_SYMBOL_GPL(tty_ldisc_deref);
+
+/**
+ * tty_set_ldisc - set line discipline
+ * @tty: the terminal to set
+ * @ldisc: the line discipline
+ *
+ * Set the discipline of a tty line. Must be called from a process
+ * context.
+ */
+
static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
{
int retval = 0;
struct tty_ldisc o_ldisc;
char buf[64];
+ int work;
+ unsigned long flags;
+ struct tty_ldisc *ld;
if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS))
return -EINVAL;
+
+ restart:
+
+ if (tty->ldisc.num == ldisc)
+ return 0; /* We are already in the desired discipline */
+
+ ld = tty_ldisc_get(ldisc);
/* Eduardo Blanco <ejbs@xxxxxxxxxxxx> */
/* Cyrus Durgin <cider@xxxxxxxxxxxxx> */
- if (!(ldiscs[ldisc].flags & LDISC_FLAG_DEFINED)) {
+ if (ld == NULL) {
char modname [20];
sprintf(modname, "tty-ldisc-%d", ldisc);
request_module (modname);
- }
- if (!(ldiscs[ldisc].flags & LDISC_FLAG_DEFINED))
+ ld = tty_ldisc_get(ldisc); }
+ if (ld == NULL)
return -EINVAL;
- if (tty->ldisc.num == ldisc)
- return 0; /* We are already in the desired discipline */
- o_ldisc = tty->ldisc;
+ /*
+ * Make sure we don't change while someone holds a
+ * reference to the line discipline. The TTY_LDISC bit
+ * prevents anyone taking a reference once it is clear.
+ * We need the lock to avoid racing reference takers.
+ */
+
+ spin_lock_irqsave(&tty_ldisc_lock, flags);
+ if(tty->ldisc.refcount)
+ {
+ /* Free the new ldisc we grabbed. Must drop the lock
+ first. */
+ spin_unlock_irqrestore(&tty_ldisc_lock, flags);
+ tty_ldisc_put(ldisc);
+ if(wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) < 0)
+ return -ERESTARTSYS;
+ goto restart;
+ }
+ clear_bit(TTY_LDISC, &tty->flags);
+ clear_bit(TTY_DONT_FLIP, &tty->flags);
+ spin_unlock_irqrestore(&tty_ldisc_lock, flags);
+
+ /*
+ * From this point on we know nobody has an ldisc
+ * usage reference, nor can they obtain one until
+ * we say so later on.
+ */
+ o_ldisc = tty->ldisc;
tty_wait_until_sent(tty, 0);
/* Shutdown the current discipline. */
@@ -249,16 +465,20 @@
(tty->ldisc.close)(tty);
/* Now set up the new line discipline. */
- tty->ldisc = ldiscs[ldisc];
- tty->termios->c_line = ldisc;
+ tty_ldisc_assign(tty, ld);
+ tty_set_termios_ldisc(tty, ldisc);
if (tty->ldisc.open)
retval = (tty->ldisc.open)(tty);
if (retval < 0) {
- tty->ldisc = o_ldisc;
- tty->termios->c_line = tty->ldisc.num;
+ tty_ldisc_put(ldisc);
+ /* There is an outstanding reference here so this is safe */
+ tty_ldisc_assign(tty, tty_ldisc_get(o_ldisc.num));
+ tty_set_termios_ldisc(tty, tty->ldisc.num);
if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) {
- tty->ldisc = ldiscs[N_TTY];
- tty->termios->c_line = N_TTY;
+ tty_ldisc_put(o_ldisc.num);
+ /* This driver is always present */
+ tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
+ tty_set_termios_ldisc(tty, N_TTY);
if (tty->ldisc.open) {
int r = tty->ldisc.open(tty);
@@ -269,8 +489,23 @@
}
}
}
+ /* At this point we hold a reference to the new ldisc and a
+ reference to the old ldisc. If we ended up flipping back
+ to the existing ldisc we have two references to it */
+
if (tty->ldisc.num != o_ldisc.num && tty->driver.set_ldisc)
tty->driver.set_ldisc(tty);
+
+ tty_ldisc_put(o_ldisc.num);
+
+ /*
+ * Allow ldisc referencing to occur as soon as the driver
+ * ldisc callback completes.
+ */
+
+ set_bit(TTY_LDISC, &tty->flags);
+ wake_up(&tty_ldisc_wait);
+
return retval;
}
@@ -385,6 +620,25 @@
};
/*
+ * Internal and external helper for wakeups of tty
+ */
+
+void tty_wakeup(struct tty_struct *tty)
+{
+ struct tty_ldisc *ld;
+
+ if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
+ ld = tty_ldisc_ref(tty);
+ if(ld) {
+ if(ld->write_wakeup)
+ ld->write_wakeup(tty);
+ tty_ldisc_deref(ld);
+ }
+ }
+}
+
+EXPORT_SYMBOL_GPL(tty_wakeup);
+/*
* This can be called through the "tq_scheduler"
* task-list. That is process synchronous, but
* doesn't hold any locks, so we need to make
@@ -397,6 +651,7 @@
struct file * filp;
struct file * cons_filp = NULL;
struct task_struct *p;
+ struct tty_ldisc *ld;
int closecount = 0, n;
if (!tty)
@@ -426,19 +681,18 @@
}
/* FIXME! What are the locking issues here? This may me overdoing things.. */
- {
- unsigned long flags;
-
- save_flags(flags); cli();
- if (tty->ldisc.flush_buffer)
- tty->ldisc.flush_buffer(tty);
+ ld = tty_ldisc_ref(tty);
+ if(ld != NULL)
+ {
+ if (ld->flush_buffer)
+ ld->flush_buffer(tty);
if (tty->driver.flush_buffer)
tty->driver.flush_buffer(tty);
- if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
- restore_flags(flags);
- }
+ if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && ld->write_wakeup)
+ ld->write_wakeup(tty);
+ //if (ld->hangup)
+ // ld->hangup(tty);
+ }
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->read_wait);
@@ -448,20 +702,17 @@
* Shutdown the current line discipline, and reset it to
* N_TTY.
*/
+
if (tty->driver.flags & TTY_DRIVER_RESET_TERMIOS)
+ {
+ unsigned long flags;
+ spin_lock_irqsave(&tty_termios_lock, flags);
*tty->termios = tty->driver.init_termios;
- if (tty->ldisc.num != ldiscs[N_TTY].num) {
- if (tty->ldisc.close)
- (tty->ldisc.close)(tty);
- tty->ldisc = ldiscs[N_TTY];
- tty->termios->c_line = N_TTY;
- if (tty->ldisc.open) {
- int i = (tty->ldisc.open)(tty);
- if (i < 0)
- printk("do_tty_hangup: N_TTY open: error %d\n",
- -i);
- }
+ spin_unlock_irqrestore(&tty_termios_lock, flags);
}
+
+ /* Defer ldisc switch */
+ /* tty_deferred_ldisc_switch(N_TTY); */
read_lock(&tasklist_lock);
for_each_task(p) {
@@ -493,6 +744,15 @@
tty->driver.close(tty, cons_filp);
} else if (tty->driver.hangup)
(tty->driver.hangup)(tty);
+
+ /* We don't want to have driver/ldisc interactions beyond
+ the ones we did here. The driver layer expects no
+ calls after ->hangup() from the ldisc side. However we
+ can't yet guarantee all that */
+
+ set_bit(TTY_HUPPED, &tty->flags);
+ if(ld)
+ tty_ldisc_deref(ld);
unlock_kernel();
}
@@ -602,9 +862,8 @@
}
if (tty->driver.start)
(tty->driver.start)(tty);
- if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
- tty->ldisc.write_wakeup)
- (tty->ldisc.write_wakeup)(tty);
+ /* If we have a running line discipline it may need kicking */
+ tty_wakeup(tty);
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->poll_wait);
}
@@ -615,6 +874,7 @@
int i;
struct tty_struct * tty;
struct inode *inode;
+ struct tty_ldisc *ld;
/* Can't seek (pread) on ttys. */
if (ppos != &file->f_pos)
@@ -643,10 +903,16 @@
return -ERESTARTSYS;
}
#endif
- if (tty->ldisc.read)
- i = (tty->ldisc.read)(tty,file,buf,count);
+ /* We want to wait for the line discipline to sort out in this
+ situation */
+ ld = tty_ldisc_ref_wait(tty);
+ lock_kernel();
+ if (ld->read)
+ i = (ld->read)(tty,file,buf,count);
else
i = -EIO;
+ tty_ldisc_deref(ld);
+ unlock_kernel();
if (i > 0)
inode->i_atime = CURRENT_TIME;
return i;
@@ -717,7 +983,9 @@
int is_console;
struct tty_struct * tty;
struct inode *inode;
-
+ ssize_t ret;
+ struct tty_ldisc *ld;
+
/* Can't seek (pwrite) on ttys. */
if (ppos != &file->f_pos)
return -ESPIPE;
@@ -749,10 +1017,15 @@
}
}
#endif
- if (!tty->ldisc.write)
- return -EIO;
- return do_tty_write(tty->ldisc.write, tty, file,
- (const unsigned char *)buf, count);
+
+ ld = tty_ldisc_ref_wait(tty);
+ if (!ld->write)
+ ret = -EIO;
+ else
+ ret = do_tty_write(ld->write, tty, file,
+ (const unsigned char *) buf, count);
+ tty_ldisc_deref(ld);
+ return ret;
}
/* Semaphore to protect creating and releasing a tty */
@@ -917,7 +1190,9 @@
(tty->ldisc.close)(tty);
goto release_mem_out;
}
- }
+ set_bit(TTY_LDISC, &o_tty->flags);
+ }
+ set_bit(TTY_LDISC, &tty->flags);
goto success;
/*
@@ -945,7 +1220,9 @@
}
tty->count++;
tty->driver = *driver; /* N.B. why do this every time?? */
-
+ /* FIXME */
+ if(!test_bit(TTY_LDISC, &tty->flags))
+ printk(KERN_ERR "init_dev but no ldisc\n");
success:
*ret_tty = tty;
@@ -1023,6 +1300,7 @@
int pty_master, tty_closing, o_tty_closing, do_sleep;
int idx;
char buf[64];
+ unsigned long flags;
tty = (struct tty_struct *)filp->private_data;
if (tty_paranoia_check(tty, filp->f_dentry->d_inode->i_rdev, "release_dev"))
@@ -1225,17 +1503,51 @@
#endif
/*
+ * Prevent flush_to_ldisc() from rescheduling the work for later. Then
+ * kill any delayed work. As this is the final close it does not
+ * race with the set_ldisc code path.
+ */
+ clear_bit(TTY_LDISC, &tty->flags);
+ clear_bit(TTY_DONT_FLIP, &tty->flags);
+
+ /*
+ * Wait for any short term users (we know they are just driver
+ * side waiters as the file is closing so user count on the file
+ * side is zero.
+ */
+
+ spin_lock_irqsave(&tty_ldisc_lock, flags);
+ while(tty->ldisc.refcount)
+ {
+ spin_unlock_irqrestore(&tty_ldisc_lock, flags);
+ wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0);
+ spin_lock_irqsave(&tty_ldisc_lock, flags);
+ }
+ spin_unlock_irqrestore(&tty_ldisc_lock, flags);
+
+ /*
* Shutdown the current line discipline, and reset it to N_TTY.
* N.B. why reset ldisc when we're releasing the memory??
+ * FIXME: this MUST get fixed for the new reflocking
*/
if (tty->ldisc.close)
(tty->ldisc.close)(tty);
- tty->ldisc = ldiscs[N_TTY];
- tty->termios->c_line = N_TTY;
+ tty_ldisc_put(tty->ldisc.num);
+
+ /*
+ * Switch the line discipline back
+ */
+ tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
+ tty_set_termios_ldisc(tty,N_TTY);
+
if (o_tty) {
+ /* FIXME: could o_tty be in setldisc here ? */
+ clear_bit(TTY_LDISC, &o_tty->flags);
if (o_tty->ldisc.close)
(o_tty->ldisc.close)(o_tty);
- o_tty->ldisc = ldiscs[N_TTY];
+ tty_ldisc_put(o_tty->ldisc.num);
+ tty_ldisc_assign(o_tty, tty_ldisc_get(N_TTY));
+ tty_set_termios_ldisc(o_tty,N_TTY);
}
/*
@@ -1409,14 +1721,18 @@
static unsigned int tty_poll(struct file * filp, poll_table * wait)
{
struct tty_struct * tty;
+ struct tty_ldisc *ld;
+ int ret = 0;
tty = (struct tty_struct *)filp->private_data;
if (tty_paranoia_check(tty, filp->f_dentry->d_inode->i_rdev, "tty_poll"))
return 0;
- if (tty->ldisc.poll)
- return (tty->ldisc.poll)(tty, filp, wait);
- return 0;
+ ld = tty_ldisc_ref_wait(tty);
+ if (ld->poll)
+ ret = (ld->poll)(tty, filp, wait);
+ tty_ldisc_deref(ld);
+ return ret;
}
/*
@@ -1493,12 +1809,15 @@
static int tiocsti(struct tty_struct *tty, char * arg)
{
char ch, mbz = 0;
+ struct tty_ldisc *ld;
if ((current->tty != tty) && !suser())
return -EPERM;
if (get_user(ch, arg))
return -EFAULT;
- tty->ldisc.receive_buf(tty, &ch, &mbz, 1);
+ ld = tty_ldisc_ref_wait(tty);
+ ld->receive_buf(tty, &ch, &mbz, 1);
+ tty_ldisc_deref(ld);
return 0;
}
@@ -1679,6 +1998,7 @@
{
struct tty_struct *tty, *real_tty;
int retval;
+ struct tty_ldisc *ld;
tty = (struct tty_struct *)file->private_data;
if (tty_paranoia_check(tty, inode->i_rdev, "tty_ioctl"))
@@ -1766,6 +2086,7 @@
case TIOCGSID:
return tiocgsid(tty, real_tty, (pid_t *) arg);
case TIOCGETD:
+ /* FIXME: check this is ok */
return put_user(tty->ldisc.num, (int *) arg);
case TIOCSETD:
return tiocsetd(tty, (int *) arg);
@@ -1799,16 +2120,20 @@
return send_break(tty, arg ? arg*(HZ/10) : HZ/4);
}
if (tty->driver.ioctl) {
- int retval = (tty->driver.ioctl)(tty, file, cmd, arg);
+ retval = (tty->driver.ioctl)(tty, file, cmd, arg);
if (retval != -ENOIOCTLCMD)
return retval;
}
- if (tty->ldisc.ioctl) {
- int retval = (tty->ldisc.ioctl)(tty, file, cmd, arg);
- if (retval != -ENOIOCTLCMD)
- return retval;
+ ld = tty_ldisc_ref_wait(tty);
+ retval = -EINVAL;
+ if (ld->ioctl) {
+ if(likely(test_bit(TTY_LDISC, &tty->flags)))
+ retval = ld->ioctl(tty, file, cmd, arg);
+ if (retval == -ENOIOCTLCMD)
+ retval = -EINVAL;
}
- return -EINVAL;
+ tty_ldisc_deref(ld);
+ return retval;
}
@@ -1833,14 +2158,20 @@
int session;
int i;
struct file *filp;
+ struct tty_ldisc *disc;
if (!tty)
return;
session = tty->session;
- if (tty->ldisc.flush_buffer)
- tty->ldisc.flush_buffer(tty);
+ /* We don't want an ldisc switch during this */
+ disc = tty_ldisc_ref(tty);
+ if (disc && disc->flush_buffer)
+ disc->flush_buffer(tty);
+ tty_ldisc_deref(disc);
+
if (tty->driver.flush_buffer)
tty->driver.flush_buffer(tty);
+
read_lock(&tasklist_lock);
for_each_task(p) {
if ((p->tty == tty) ||
@@ -1872,10 +2203,15 @@
char *fp;
int count;
unsigned long flags;
+ struct tty_ldisc *disc;
+
+ disc = tty_ldisc_ref(tty);
+ if (disc == NULL) /* !TTY_LDISC */
+ return;
if (test_bit(TTY_DONT_FLIP, &tty->flags)) {
queue_task(&tty->flip.tqueue, &tq_timer);
- return;
+ goto out;
}
if (tty->flip.buf_num) {
cp = tty->flip.char_buf + TTY_FLIPBUF_SIZE;
@@ -1897,8 +2233,31 @@
count = tty->flip.count;
tty->flip.count = 0;
restore_flags(flags);
-
- tty->ldisc.receive_buf(tty, cp, fp, count);
+ disc->receive_buf(tty, cp, fp, count);
+ out:
+ tty_ldisc_deref(disc);
+}
+
+/*
+ * Call the ldisc flush directly from a driver. This function may
+ * return an error and need retrying by the user.
+ */
+
+int tty_push_data(struct tty_struct *tty, unsigned char *cp, unsigned char *fp, int count)
+{
+ int ret = 0;
+ struct tty_ldisc *disc;
+
+ disc = tty_ldisc_ref(tty);
+ if(test_bit(TTY_DONT_FLIP, &tty->flags))
+ ret = -EAGAIN;
+ else if(disc == NULL)
+ ret = -EIO;
+ else
+ disc->receive_buf(tty, cp, fp, count);
+ tty_ldisc_deref(disc);
+ return ret;
+
}
/*
@@ -1960,7 +2319,7 @@
{
memset(tty, 0, sizeof(struct tty_struct));
tty->magic = TTY_MAGIC;
- tty->ldisc = ldiscs[N_TTY];
+ tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
tty->pgrp = -1;
tty->flip.char_buf_ptr = tty->flip.char_buf;
tty->flip.flag_buf_ptr = tty->flip.flag_buf;
@@ -2080,7 +2439,7 @@
long __init console_init(long kmem_start, long kmem_end)
{
/* Setup the default TTY line discipline. */
- memset(ldiscs, 0, sizeof(ldiscs));
+ memset(tty_ldiscs, 0, NR_LDISCS*sizeof(struct tty_ldisc));
(void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
/*
diff -urN linux-2.2.26.orig/drivers/char/tty_ioctl.c linux-2.2.26/drivers/char/tty_ioctl.c
--- linux-2.2.26.orig/drivers/char/tty_ioctl.c 2001-03-25 18:31:24.000000000 +0200
+++ linux-2.2.26/drivers/char/tty_ioctl.c 2004-10-31 12:06:32.000000000 +0100
@@ -33,6 +33,8 @@
# define PRINTK(x) /**/
#endif
+extern spinlock_t tty_termios_lock;
+
/*
* Internal flag options for termios setting behavior
*/
@@ -100,8 +102,17 @@
{
int canon_change;
struct termios old_termios = *tty->termios;
+ struct tty_ldisc *ld;
+ unsigned long flags;
+
+ /*
+ * Perform the actual termios internal changes under lock.
+ */
+
+ /* FIXME: we need to decide on some locking/ordering semantics
+ for the set_termios notification eventually */
+ spin_lock_irqsave(&tty_termios_lock, flags);
- cli();
*tty->termios = *new_termios;
unset_locked_termios(tty->termios, &old_termios, tty->termios_locked);
canon_change = (old_termios.c_lflag ^ tty->termios->c_lflag) & ICANON;
@@ -111,7 +122,7 @@
tty->canon_data = 0;
tty->erasing = 0;
}
- sti();
+
if (canon_change && !L_ICANON(tty) && tty->read_cnt)
{
/* Get characters left over from canonical mode. */
@@ -142,16 +153,21 @@
if (tty->driver.set_termios)
(*tty->driver.set_termios)(tty, &old_termios);
- if (tty->ldisc.set_termios)
- (*tty->ldisc.set_termios)(tty, &old_termios);
+ ld = tty_ldisc_ref(tty);
+ if (ld != NULL) {
+ if (ld->set_termios)
+ (ld->set_termios)(tty, &old_termios);
+ tty_ldisc_deref(ld);
+ }
+ spin_unlock_irqrestore(&tty_termios_lock, flags);
}
static int set_termios(struct tty_struct * tty, unsigned long arg, int opt)
{
struct termios tmp_termios;
- int retval;
+ struct tty_ldisc *ld;
+ int retval = tty_check_change(tty);
- retval = tty_check_change(tty);
if (retval)
return retval;
@@ -164,9 +180,13 @@
return -EFAULT;
}
- if ((opt & TERMIOS_FLUSH) && tty->ldisc.flush_buffer)
- tty->ldisc.flush_buffer(tty);
+ ld = tty_ldisc_ref(tty);
+ if (ld != NULL) {
+ if ((opt & TERMIOS_FLUSH) && ld->flush_buffer)
+ ld->flush_buffer(tty);
+ tty_ldisc_deref(ld);
+ }
if (opt & TERMIOS_WAIT) {
tty_wait_until_sent(tty, 0);
if (signal_pending(current))
@@ -230,12 +250,16 @@
static int get_sgttyb(struct tty_struct * tty, struct sgttyb * sgttyb)
{
struct sgttyb tmp;
+ unsigned long flags;
+ spin_lock_irqsave(&tty_termios_lock, flags);
tmp.sg_ispeed = 0;
tmp.sg_ospeed = 0;
tmp.sg_erase = tty->termios->c_cc[VERASE];
tmp.sg_kill = tty->termios->c_cc[VKILL];
tmp.sg_flags = get_sgflags(tty);
+ spin_unlock_irqrestore(&tty_termios_lock, flags);
+
if (copy_to_user(sgttyb, &tmp, sizeof(tmp)))
return -EFAULT;
return 0;
@@ -275,12 +299,15 @@
retval = tty_check_change(tty);
if (retval)
return retval;
- termios = *tty->termios;
+
if (copy_from_user(&tmp, sgttyb, sizeof(tmp)))
return -EFAULT;
+ spin_lock_irqsave(&tty_termios_lock, flags);
+ termios = *tty->termios;
termios.c_cc[VERASE] = tmp.sg_erase;
termios.c_cc[VKILL] = tmp.sg_kill;
set_sgflags(&termios, tmp.sg_flags);
+ spin_unlock_irqrestore(&tty_termios_lock, flags);
change_termios(tty, &termios);
return 0;
}
@@ -374,6 +401,8 @@
{
struct tty_struct * real_tty;
int retval;
+ struct tty_ldisc *ld;
+ unsigned long flags;
if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
tty->driver.subtype == PTY_TYPE_MASTER)
@@ -423,6 +452,8 @@
retval = tty_check_change(tty);
if (retval)
return retval;
+
+ ld = tty_ldisc_ref(tty);
switch (arg) {
case TCOOFF:
if (!tty->flow_stopped) {
@@ -454,20 +485,22 @@
return retval;
switch (arg) {
case TCIFLUSH:
- if (tty->ldisc.flush_buffer)
- tty->ldisc.flush_buffer(tty);
+ if (ld->flush_buffer)
+ ld->flush_buffer(tty);
break;
case TCIOFLUSH:
- if (tty->ldisc.flush_buffer)
- tty->ldisc.flush_buffer(tty);
+ if (ld->flush_buffer)
+ ld->flush_buffer(tty);
/* fall through */
case TCOFLUSH:
if (tty->driver.flush_buffer)
tty->driver.flush_buffer(tty);
break;
default:
+ tty_ldisc_deref(ld);
return -EINVAL;
}
+ tty_ldisc_deref(ld);
return 0;
case TIOCOUTQ:
return put_user(tty->driver.chars_in_buffer ?
@@ -515,9 +548,11 @@
retval = get_user(arg, (unsigned int *) arg);
if (retval)
return retval;
+ spin_lock_irqsave(&tty_termios_lock, flags);
tty->termios->c_cflag =
((tty->termios->c_cflag & ~CLOCAL) |
(arg ? CLOCAL : 0));
+ spin_unlock_irqrestore(&tty_termios_lock, flags);
return 0;
default:
return -ENOIOCTLCMD;
diff -urN linux-2.2.26.orig/drivers/net/slip.c linux-2.2.26/drivers/net/slip.c
--- linux-2.2.26.orig/drivers/net/slip.c 2001-03-25 18:31:15.000000000 +0200
+++ linux-2.2.26/drivers/net/slip.c 2004-10-24 11:09:19.428600744 +0200
@@ -669,7 +669,9 @@
* Handle the 'receiver data ready' interrupt.
* This function is called by the 'tty_io' module in the kernel when
* a block of SLIP data has been received, which can now be decapsulated
- * and sent on to some IP layer for further processing.
+ * and sent on to some IP layer for further processing. This will not
+ * be re-entered while running but other ldisc functions may be called
+ * in parallel
*/
static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
@@ -824,9 +826,11 @@
* SLIP line discipline is called for. Because we are
* sure the tty line exists, we only have to link it to
* a free SLIP channel...
+ *
+ * Called in process context serialized from other ldisc calls.
*/
-static int
-slip_open(struct tty_struct *tty)
+
+static int slip_open(struct tty_struct *tty)
{
struct slip *sl;
int err;
@@ -908,6 +912,9 @@
}
/*
+
+ FIXME: 1,2 are fixed 3 was never true anyway.
+
Let me to blame a bit.
1. TTY module calls this funstion on soft interrupt.
2. TTY module calls this function WITH MASKED INTERRUPTS!
@@ -926,9 +933,8 @@
/*
* Close down a SLIP channel.
- * This means flushing out any pending queues, and then restoring the
- * TTY line discipline to what it was before it got hooked to SLIP
- * (which usually is TTY again).
+ * This means flushing out any pending queues, and then returning. This
+ * call is serialized against other ldisc functions
*/
static void
slip_close(struct tty_struct *tty)
diff -urN linux-2.2.26.orig/drivers/sbus/char/zs.c linux-2.2.26/drivers/sbus/char/zs.c
--- linux-2.2.26.orig/drivers/sbus/char/zs.c 2001-11-02 17:39:07.000000000 +0100
+++ linux-2.2.26/drivers/sbus/char/zs.c 2004-10-31 09:43:01.192501208 +0100
@@ -1606,10 +1606,10 @@
tty->closing = 0;
info->event = 0;
info->tty = 0;
- if (tty->ldisc.num != ldiscs[N_TTY].num) {
+ if (tty->ldisc.num != N_TTY) {
if (tty->ldisc.close)
(tty->ldisc.close)(tty);
- tty->ldisc = ldiscs[N_TTY];
+ tty->ldisc = *(tty_ldisc_get(N_TTY));
tty->termios->c_line = N_TTY;
if (tty->ldisc.open)
(tty->ldisc.open)(tty);
diff -urN linux-2.2.26.orig/drivers/sgi/char/sgiserial.c linux-2.2.26/drivers/sgi/char/sgiserial.c
--- linux-2.2.26.orig/drivers/sgi/char/sgiserial.c 2001-03-25 18:31:41.000000000 +0200
+++ linux-2.2.26/drivers/sgi/char/sgiserial.c 2004-10-31 09:38:06.825251832 +0100
@@ -1465,10 +1465,10 @@
tty->closing = 0;
info->event = 0;
info->tty = 0;
- if (tty->ldisc.num != ldiscs[N_TTY].num) {
+ if (tty->ldisc.num != N_TTY) {
if (tty->ldisc.close)
(tty->ldisc.close)(tty);
- tty->ldisc = ldiscs[N_TTY];
+ tty->ldisc = *(tty_ldisc_get(N_TTY));
tty->termios->c_line = N_TTY;
if (tty->ldisc.open)
(tty->ldisc.open)(tty);
diff -urN linux-2.2.26.orig/fs/proc/proc_tty.c linux-2.2.26/fs/proc/proc_tty.c
--- linux-2.2.26.orig/fs/proc/proc_tty.c 2004-02-24 14:48:05.000000000 +0100
+++ linux-2.2.26/fs/proc/proc_tty.c 2004-10-31 13:07:51.212134232 +0100
@@ -15,8 +15,6 @@
#include <asm/bitops.h>
extern struct tty_driver *tty_drivers; /* linked list of tty drivers */
-extern struct tty_ldisc ldiscs[];
-
static int tty_drivers_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data);
@@ -112,16 +110,20 @@
int len = 0;
off_t begin = 0;
off_t end;
+ struct tty_ldisc *ld;
end = off + count; /* XXX: undefined on overflow per ISO C99 */
if (end < off)
return -EINVAL;
for (i=0; i < NR_LDISCS; i++) {
- if (!(ldiscs[i].flags & LDISC_FLAG_DEFINED))
+ ld = tty_ldisc_get(i);
+ if (ld == NULL)
+
continue;
len += sprintf(page+len, "%-10s %2d\n",
- ldiscs[i].name ? ldiscs[i].name : "???", i);
+ ld->name ? ld->name : "???", i);
+ tty_ldisc_put(i);
if (len+begin > end)
break;
if (len+begin < off) {
diff -urN linux-2.2.26.orig/include/linux/tty.h linux-2.2.26/include/linux/tty.h
--- linux-2.2.26.orig/include/linux/tty.h 2004-02-24 18:33:31.000000000 +0100
+++ linux-2.2.26/include/linux/tty.h 2004-10-24 10:59:54.653459616 +0200
@@ -319,19 +319,21 @@
* tty->write. Thus, you must use the inline functions set_bit() and
* clear_bit() to make things atomic.
*/
-#define TTY_THROTTLED 0
-#define TTY_IO_ERROR 1
-#define TTY_OTHER_CLOSED 2
-#define TTY_EXCLUSIVE 3
-#define TTY_DEBUG 4
-#define TTY_DO_WRITE_WAKEUP 5
-#define TTY_PUSH 6
-#define TTY_CLOSING 7
-#define TTY_DONT_FLIP 8
-#define TTY_HW_COOK_OUT 14
-#define TTY_HW_COOK_IN 15
-#define TTY_PTY_LOCK 16
-#define TTY_NO_WRITE_SPLIT 17
+#define TTY_THROTTLED 0 /* Call unthrottle() at threshold min */
+#define TTY_IO_ERROR 1 /* Canse an I/O error (may be no ldisc too) */
+#define TTY_OTHER_CLOSED 2 /* Other side (if any) has closed */
+#define TTY_EXCLUSIVE 3 /* Exclusive open mode */
+#define TTY_DEBUG 4 /* Debugging */
+#define TTY_DO_WRITE_WAKEUP 5 /* Call write_wakeup after queuing new */
+#define TTY_PUSH 6 /* n_tty private */
+#define TTY_CLOSING 7 /* ->close() in progress */
+#define TTY_DONT_FLIP 8 /* Defer buffer flip */
+#define TTY_LDISC 9 /* Line discipline attached */
+#define TTY_HW_COOK_OUT 14 /* Hardware can do output cooking */
+#define TTY_HW_COOK_IN 15 /* Hardware can do input cooking */
+#define TTY_PTY_LOCK 16 /* pty private */
+#define TTY_NO_WRITE_SPLIT 17 /* Preserve write boundaries to driver */
+#define TTY_HUPPED 18 /* Post driver->hangup() */
#define TTY_WRITE_FLUSH(tty) tty_write_flush((tty))
@@ -339,7 +341,7 @@
extern struct termios tty_std_termios;
extern struct tty_struct * redirect;
-extern struct tty_ldisc ldiscs[];
+extern struct tty_ldisc tty_ldiscs[];
extern int fg_console, last_console, want_console;
extern int kmsg_redirect;
@@ -393,6 +395,16 @@
extern void tty_flip_buffer_push(struct tty_struct *tty);
extern int tty_get_baud_rate(struct tty_struct *tty);
+extern struct tty_ldisc *tty_ldisc_ref(struct tty_struct *);
+extern void tty_ldisc_deref(struct tty_ldisc *);
+extern struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *);
+
+extern struct tty_ldisc *tty_ldisc_get(int);
+extern void tty_ldisc_put(int);
+
+extern void tty_wakeup(struct tty_struct *tty);
+
+
/* n_tty.c */
extern struct tty_ldisc tty_ldisc_N_TTY;
diff -urN linux-2.2.26.orig/include/linux/tty_ldisc.h linux-2.2.26/include/linux/tty_ldisc.h
--- linux-2.2.26.orig/include/linux/tty_ldisc.h 2004-02-24 18:33:31.000000000 +0100
+++ linux-2.2.26/include/linux/tty_ldisc.h 2004-10-24 11:04:07.991946312 +0200
@@ -129,6 +129,7 @@
char *fp, int count);
int (*receive_room)(struct tty_struct *);
void (*write_wakeup)(struct tty_struct *);
+int refcount;
};
#define TTY_LDISC_MAGIC 0x5403