PATCH: tty driver take 4 try 2
From: Alan Cox
Date: Thu Sep 23 2004 - 17:10:05 EST
Ok this should fix the bug
"We apologise for the inconvenience"
diff -u --new-file --recursive --exclude-from /usr/src/exclude tty.old/Documentation/tty.txt linux-2.6.9rc2/Documentation/tty.txt
--- tty.old/Documentation/tty.txt 2004-09-23 19:16:26.131074592 +0100
+++ linux-2.6.9rc2/Documentation/tty.txt 2004-09-21 14:05:02.000000000 +0100
@@ -58,8 +58,10 @@
chars_in_buffer() - Report the number of bytes in the buffer.
-set_termios() - Called on termios structure changes. Semantics
- deeply mysterious right now.
+set_termios() - Called on termios structure changes. The caller
+ passes the old termios data and the current data
+ is in the tty. Currently can be parallel entered
+ and ordering isn't predictable - FIXME
read() - Move data from the line discipline to the user.
Multiple read calls may occur in parallel and the
diff -u --new-file --recursive --exclude-from /usr/src/exclude tty.old/drivers/char/n_tty.c linux-2.6.9rc2/drivers/char/n_tty.c
--- tty.old/drivers/char/n_tty.c 2004-09-23 18:43:04.852315208 +0100
+++ linux-2.6.9rc2/drivers/char/n_tty.c 2004-09-23 10:35:50.292643816 +0100
@@ -99,11 +99,18 @@
spin_unlock_irqrestore(&tty->read_lock, flags);
}
-/*
- * Check whether to call the driver.unthrottle function.
- * We test the TTY_THROTTLED bit first so that it always
- * indicates the current state.
+/**
+ * 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. 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 &&
@@ -112,10 +119,13 @@
tty->driver->unthrottle(tty);
}
-/*
- * 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().
+/**
+ * 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)
{
@@ -129,9 +139,19 @@
check_unthrottle(tty);
}
-/*
- * 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 */
@@ -146,9 +166,14 @@
}
}
-/*
- * 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;
@@ -166,20 +191,47 @@
return n;
}
+/**
+ * is_utf8_continuation - utf8 multibyte check
+ * @c: byte to check
+ *
+ * Returns true if the utf8 character 'c' is a multibyte continuation
+ * character. We use this to correctly compute the on screen size
+ * of the character when printing
+ */
+
static inline int is_utf8_continuation(unsigned char c)
{
return (c & 0xc0) == 0x80;
}
+/**
+ * is_continuation - multibyte check
+ * @c: byte to check
+ *
+ * Returns true if the utf8 character 'c' is a multibyte continuation
+ * character and the terminal is in unicode mode.
+ */
+
static inline int is_continuation(unsigned char c, struct tty_struct *tty)
{
return I_IUTF8(tty) && is_utf8_continuation(c);
}
-/*
- * Perform OPOST processing. Returns -1 when the output device is
- * full and the character must be retried.
+/**
+ * opost - output post processor
+ * @c: character (or partial unicode symbol)
+ * @tty: terminal device
+ *
+ * Perform OPOST processing. Returns -1 when the output device is
+ * full and the character must be retried. Note that Linux currently
+ * ignores TABDLY, CRDLY, VTDLY, FFDLY and NLDLY. They simply aren't
+ * relevant in the world today. If you ever need them, add them here.
+ *
+ * Called from both the receive and transmit sides and can be called
+ * re-entrantly. Relies on lock_kernel() still.
*/
+
static int opost(unsigned char c, struct tty_struct *tty)
{
int space, spaces;
@@ -239,10 +291,20 @@
return 0;
}
-/*
- * 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 __user * inbuf, unsigned int nr)
{
@@ -304,13 +366,27 @@
}
-
+/**
+ * put_char - write character to driver
+ * @c: character (or part of unicode symbol)
+ * @tty: terminal device
+ *
+ * Queue a byte to the driver layer for output
+ */
+
static inline void put_char(unsigned char c, struct tty_struct *tty)
{
tty->driver->put_char(tty, c);
}
-/* Must be called only when L_ECHO(tty) is true. */
+/**
+ * echo_char - echo characters
+ * @c: unicode byte to echo
+ * @tty: terminal device
+ *
+ * Echo user input back onto the screen. This must be called only when
+ * L_ECHO(tty) is true. Called from the driver receive_buf path.
+ */
static void echo_char(unsigned char c, struct tty_struct *tty)
{
@@ -331,6 +407,16 @@
}
}
+/**
+ * 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;
@@ -463,6 +549,18 @@
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)
@@ -474,6 +572,16 @@
}
}
+/**
+ * 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))
@@ -490,19 +598,40 @@
wake_up_interruptible(&tty->read_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)
{
@@ -520,6 +649,16 @@
wake_up_interruptible(&tty->read_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)
{
unsigned long flags;
@@ -711,6 +850,16 @@
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;
@@ -729,10 +878,13 @@
return 0;
}
-/*
- * Required for the ptys, serial driver etc. since processes
- * that attach themselves to the master and rely on ASYNC
- * IO must be woken up
+/**
+ * n_tty_write_wakeup - asynchronous I/O notifier
+ * @tty: tty device
+ *
+ * Required for the ptys, serial driver etc. since processes
+ * that attach themselves to the master and rely on ASYNC
+ * IO must be woken up
*/
static void n_tty_write_wakeup(struct tty_struct *tty)
@@ -745,6 +897,19 @@
return;
}
+/**
+ * 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 flush_to_ldisc)
+ */
+
static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
char *fp, int count)
{
@@ -828,6 +993,18 @@
current->sighand->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)
@@ -843,7 +1020,6 @@
I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
I_PARMRK(tty)) {
- local_irq_disable(); // FIXME: is this safe?
memset(tty->process_char_map, 0, 256/8);
if (I_IGNCR(tty) || I_ICRNL(tty))
@@ -879,7 +1055,6 @@
set_bit(SUSP_CHAR(tty), tty->process_char_map);
}
clear_bit(__DISABLED_CHAR, tty->process_char_map);
- local_irq_enable(); // FIXME: is this safe?
tty->raw = 0;
tty->real_raw = 0;
} else {
@@ -893,6 +1068,16 @@
}
}
+/**
+ * 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);
@@ -902,11 +1087,22 @@
}
}
+/**
+ * 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)
return -EINVAL;
+ /* This one is ugly. Currently a malloc failure here can panic */
if (!tty->read_buf) {
tty->read_buf = alloc_buf();
if (!tty->read_buf)
@@ -932,14 +1128,23 @@
return 0;
}
-/*
- * 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
- * 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.
+/**
+ * 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
+ * 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 __user **b,
size_t *nr)
@@ -970,25 +1175,18 @@
extern ssize_t redirected_tty_write(struct file *,const char *,size_t,loff_t *);
-static ssize_t read_chan(struct tty_struct *tty, struct file *file,
- unsigned char __user *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 __user *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;
- }
-
/* 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
@@ -1006,7 +1204,48 @@
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 __user *buf, size_t nr)
+{
+ unsigned char __user *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) {
@@ -1028,6 +1267,9 @@
}
}
+ /*
+ * Internal serialization of reads.
+ */
if (file->f_flags & O_NONBLOCK) {
if (down_trylock(&tty->atomic_read))
return -EAGAIN;
@@ -1177,6 +1419,21 @@
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 __user * buf, size_t nr)
{
@@ -1246,7 +1503,25 @@
return (b - buf) ? b - buf : retval;
}
-/* Called without the kernel lock held - fine */
+/**
+ * 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;
@@ -1287,6 +1562,7 @@
n_tty_ioctl, /* ioctl */
n_tty_set_termios, /* set_termios */
normal_poll, /* poll */
+ NULL, /* hangup */
n_tty_receive_buf, /* receive_buf */
n_tty_receive_room, /* receive_room */
n_tty_write_wakeup /* write_wakeup */
diff -u --new-file --recursive --exclude-from /usr/src/exclude tty.old/drivers/char/pcmcia/synclink_cs.c linux-2.6.9rc2/drivers/char/pcmcia/synclink_cs.c
--- tty.old/drivers/char/pcmcia/synclink_cs.c 2004-09-23 19:16:12.718113672 +0100
+++ linux-2.6.9rc2/drivers/char/pcmcia/synclink_cs.c 2004-09-17 18:03:37.000000000 +0100
@@ -516,6 +516,40 @@
return mgslpc_get_text_ptr;
}
+/**
+ * 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);
+ }
+}
+
static dev_link_t *mgslpc_attach(void)
{
MGSLPC_INFO *info;
@@ -969,13 +1003,7 @@
printk("bh_transmit() entry on %s\n", 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);
}
}
@@ -1860,11 +1888,9 @@
info->tx_count = info->tx_put = info->tx_get = 0;
del_timer(&info->tx_timer);
spin_unlock_irqrestore(&info->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);
}
/* Send a high-priority XON/XOFF character
@@ -2573,9 +2599,8 @@
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);
@@ -4040,11 +4065,7 @@
hdlcdev_rx(info, buf->data, framesize);
else
#endif
- {
- /* Call the line discipline receive callback directly. */
- if (tty && tty->ldisc.receive_buf)
- tty->ldisc.receive_buf(tty, buf->data, info->flag_buf, framesize);
- }
+ ldisc_receive_buf(tty, buf->data, info->flag_buf, framesize);
}
}
diff -u --new-file --recursive --exclude-from /usr/src/exclude tty.old/drivers/char/synclink.c linux-2.6.9rc2/drivers/char/synclink.c
--- tty.old/drivers/char/synclink.c 2004-09-23 19:16:12.736110936 +0100
+++ linux-2.6.9rc2/drivers/char/synclink.c 2004-09-17 18:03:37.000000000 +0100
@@ -975,6 +975,40 @@
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
@@ -1135,13 +1169,7 @@
__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);
}
@@ -2397,11 +2425,8 @@
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()
*
@@ -3235,9 +3260,8 @@
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);
@@ -6810,11 +6834,7 @@
hdlcdev_rx(info,info->intermediate_rxbuffer,framesize);
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. */
@@ -6986,9 +7006,7 @@
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 -u --new-file --recursive --exclude-from /usr/src/exclude tty.old/drivers/char/synclinkmp.c linux-2.6.9rc2/drivers/char/synclinkmp.c
--- tty.old/drivers/char/synclinkmp.c 2004-09-23 19:16:12.740110328 +0100
+++ linux-2.6.9rc2/drivers/char/synclinkmp.c 2004-09-17 18:03:37.000000000 +0100
@@ -699,6 +699,40 @@
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);
+ }
+}
+
/* tty callbacks */
/* Called when a port is opened. Init and enable port.
@@ -846,8 +880,7 @@
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);
@@ -1252,9 +1285,7 @@
spin_unlock_irqrestore(&info->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);
}
/* throttle (stop) transmitter
@@ -2123,13 +2154,7 @@
__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):%s calling ldisc.write_wakeup\n",
- __FILE__,__LINE__,info->device_name);
- (tty->ldisc.write_wakeup)(tty);
- }
+ tty_wakeup(tty);
wake_up_interruptible(&tty->write_wait);
}
}
@@ -5051,15 +5076,8 @@
hdlcdev_rx(info,info->tmp_rx_buf,framesize);
else
#endif
- {
- if ( tty && tty->ldisc.receive_buf ) {
- /* Call the line discipline receive callback directly. */
- tty->ldisc.receive_buf(tty,
- info->tmp_rx_buf,
- info->flag_buf,
- framesize);
- }
- }
+ ldisc_receive_buf(tty,info->tmp_rx_buf,
+ info->flag_buf, framesize);
}
}
/* Free the buffers used by this frame. */
diff -u --new-file --recursive --exclude-from /usr/src/exclude tty.old/drivers/char/tty_io.c linux-2.6.9rc2/drivers/char/tty_io.c
--- tty.old/drivers/char/tty_io.c 2004-09-23 19:16:26.150071704 +0100
+++ linux-2.6.9rc2/drivers/char/tty_io.c 2004-09-23 22:27:29.269412680 +0100
@@ -130,6 +130,8 @@
/* Semaphore to protect creating and releasing a tty. This is shared with
vt.c for deeply disgusting hack reasons */
DECLARE_MUTEX(tty_sem);
+/* Lock for tty_termios changes - private to tty_io/tty_ioctl */
+spinlock_t tty_termios_lock = SPIN_LOCK_UNLOCKED;
#ifdef CONFIG_UNIX98_PTYS
extern struct tty_driver *ptm_driver; /* Unix98 pty masters; for /dev/ptmx */
@@ -230,6 +232,20 @@
}
/*
+ * 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.
@@ -365,7 +381,7 @@
/* wait_event is a macro */
wait_event(tty_ldisc_wait, tty_ldisc_try(tty));
if(tty->ldisc.refcount == 0)
- printk("Ref wait -> 0 ref\n");
+ printk(KERN_ERR "tty_ldisc_ref_wait\n");
return &tty->ldisc;
}
@@ -406,7 +422,7 @@
spin_lock_irqsave(&tty_ldisc_lock, flags);
if(ld->refcount == 0)
- printk(KERN_EMERG "tty_ldisc_deref: no references.\n");
+ printk(KERN_ERR "tty_ldisc_deref: no references.\n");
else
ld->refcount--;
if(ld->refcount == 0)
@@ -503,19 +519,19 @@
/* Now set up the new line discipline. */
tty_ldisc_assign(tty, ld);
- tty->termios->c_line = ldisc;
+ tty_set_termios_ldisc(tty, ldisc);
if (tty->ldisc.open)
retval = (tty->ldisc.open)(tty);
if (retval < 0) {
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->termios->c_line = tty->ldisc.num;
+ tty_set_termios_ldisc(tty, tty->ldisc.num);
if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) {
tty_ldisc_put(o_ldisc.num);
/* This driver is always present */
tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
- tty->termios->c_line = N_TTY;
+ tty_set_termios_ldisc(tty, N_TTY);
if (tty->ldisc.open) {
int r = tty->ldisc.open(tty);
@@ -711,6 +727,7 @@
check_tty_count(tty, "do_tty_hangup");
file_list_lock();
+ /* This breaks for file handles being sent over AF_UNIX sockets ? */
list_for_each_entry(filp, &tty->tty_files, f_list) {
if (filp->f_op->write == redirected_tty_write)
cons_filp = filp;
@@ -723,7 +740,7 @@
file_list_unlock();
/* FIXME! What are the locking issues here? This may me overdoing things..
- * this question is especially important now that we've removed the irqlock. */
+ * this question is especially important now that we've removed the irqlock. */
ld = tty_ldisc_ref(tty);
if(ld != NULL) /* We may have no line discipline at this point */
@@ -735,8 +752,13 @@
if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
ld->write_wakeup)
ld->write_wakeup(tty);
+ if (ld->hangup)
+ ld->hangup(tty);
}
+ /* FIXME: Once we trust the LDISC code better we can wait here for
+ ldisc completion and fix the driver call race */
+
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->read_wait);
@@ -745,8 +767,13 @@
* 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;
-
+ spin_unlock_irqrestore(&tty_termios_lock, flags);
+ }
+
/* Defer ldisc switch */
/* tty_deferred_ldisc_switch(N_TTY);
@@ -785,8 +812,13 @@
} else if (tty->driver->hangup)
(tty->driver->hangup)(tty);
- if(ld)
- {
+ /* 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) {
set_bit(TTY_LDISC, &tty->flags);
tty_ldisc_deref(ld);
}
@@ -895,8 +927,6 @@
void start_tty(struct tty_struct *tty)
{
- struct tty_ldisc *ld;
-
if (!tty->stopped || tty->flow_stopped)
return;
tty->stopped = 0;
@@ -908,12 +938,8 @@
if (tty->driver->start)
(tty->driver->start)(tty);
- /* If we have a running line discipline it may need kicking */
- ld = tty_ldisc_ref(tty);
- if (ld && (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) &&
- ld->write_wakeup)
- (ld->write_wakeup)(tty);
- tty_ldisc_deref(ld);
+ /* If we have a running line discipline it may need kicking */
+ tty_wakeup(tty);
wake_up_interruptible(&tty->write_wait);
}
@@ -1367,6 +1393,7 @@
int devpts_master, devpts;
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, "release_dev"))
@@ -1580,7 +1607,20 @@
*/
flush_scheduled_work();
-
+
+ /*
+ * 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??
@@ -1595,7 +1635,7 @@
* Switch the line discipline back
*/
tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
- tty->termios->c_line = 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);
@@ -1603,8 +1643,8 @@
(o_tty->ldisc.close)(o_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);
}
-
/*
* The release_mem function takes care of the details of clearing
* the slots and preserving the termios structure.
@@ -1858,12 +1898,8 @@
if (get_user(ch, p))
return -EFAULT;
ld = tty_ldisc_ref_wait(tty);
- /* FIXME: suppose this is NOFLIP ?? */
- if(ld)
- {
- ld->receive_buf(tty, &ch, &mbz, 1);
- tty_ldisc_deref(ld);
- }
+ ld->receive_buf(tty, &ch, &mbz, 1);
+ tty_ldisc_deref(ld);
return 0;
}
@@ -2441,7 +2477,11 @@
int tty_termios_baud_rate(struct termios *termios)
{
- unsigned int cbaud = termios->c_cflag & CBAUD;
+ unsigned int cbaud;
+ unsigned long flags;
+
+ spin_lock_irqsave(&tty_termios_lock, flags);
+ cbaud = termios->c_cflag & CBAUD;
if (cbaud & CBAUDEX) {
cbaud &= ~CBAUDEX;
@@ -2451,7 +2491,7 @@
else
cbaud += 15;
}
-
+ spin_unlock_irqrestore(&tty_termios_lock, flags);
return baud_table[cbaud];
}
diff -u --new-file --recursive --exclude-from /usr/src/exclude tty.old/drivers/char/tty_ioctl.c linux-2.6.9rc2/drivers/char/tty_ioctl.c
--- tty.old/drivers/char/tty_ioctl.c 2004-09-23 19:16:26.150071704 +0100
+++ linux-2.6.9rc2/drivers/char/tty_ioctl.c 2004-09-21 15:05:41.000000000 +0100
@@ -29,6 +29,8 @@
#undef DEBUG
+extern spinlock_t tty_termios_lock;
+
/*
* Internal flag options for termios setting behavior
*/
@@ -99,8 +101,17 @@
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);
- local_irq_disable(); // FIXME: is this safe?
*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;
@@ -110,12 +121,13 @@
tty->canon_data = 0;
tty->erasing = 0;
}
- local_irq_enable(); // FIXME: is this safe?
+
+
if (canon_change && !L_ICANON(tty) && tty->read_cnt)
/* Get characters left over from canonical mode. */
wake_up_interruptible(&tty->read_wait);
- /* see if packet mode change of state */
+ /* See if packet mode change of state. */
if (tty->link && tty->link->packet) {
int old_flow = ((old_termios.c_iflag & IXON) &&
@@ -133,14 +145,17 @@
wake_up_interruptible(&tty->link->read_wait);
}
}
-
+
if (tty->driver->set_termios)
(*tty->driver->set_termios)(tty, &old_termios);
ld = tty_ldisc_ref(tty);
- if (ld->set_termios)
- (ld->set_termios)(tty, &old_termios);
- tty_ldisc_deref(ld);
+ 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, void __user *arg, int opt)
@@ -234,12 +249,16 @@
static int get_sgttyb(struct tty_struct * tty, struct sgttyb __user * 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);
+
return copy_to_user(sgttyb, &tmp, sizeof(tmp)) ? -EFAULT : 0;
}
@@ -278,12 +297,16 @@
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;
}
@@ -375,6 +398,7 @@
void __user *p = (void __user *)arg;
int retval;
struct tty_ldisc *ld;
+ unsigned long flags;
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
@@ -518,9 +542,11 @@
case TIOCSSOFTCAR:
if (get_user(arg, (unsigned int __user *) arg))
return -EFAULT;
+ 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 -u --new-file --recursive --exclude-from /usr/src/exclude tty.old/drivers/usb/serial/ir-usb.c linux-2.6.9rc2/drivers/usb/serial/ir-usb.c
--- tty.old/drivers/usb/serial/ir-usb.c 2004-09-23 18:43:47.023904152 +0100
+++ linux-2.6.9rc2/drivers/usb/serial/ir-usb.c 2004-09-23 10:37:21.235818352 +0100
@@ -449,6 +449,10 @@
*/
tty = port->tty;
+ /*
+ * FIXME: must not do this in IRQ context,
+ * must honour TTY_DONT_FLIP
+ */
tty->ldisc.receive_buf(
tty,
data+1,
diff -u --new-file --recursive --exclude-from /usr/src/exclude tty.old/include/linux/tty.h linux-2.6.9rc2/include/linux/tty.h
--- tty.old/include/linux/tty.h 2004-09-23 19:16:26.163069728 +0100
+++ linux-2.6.9rc2/include/linux/tty.h 2004-09-21 14:57:41.000000000 +0100
@@ -320,6 +320,7 @@
#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))
diff -u --new-file --recursive --exclude-from /usr/src/exclude tty.old/include/linux/tty_ldisc.h linux-2.6.9rc2/include/linux/tty_ldisc.h
--- tty.old/include/linux/tty_ldisc.h 2004-09-23 19:16:26.163069728 +0100
+++ linux-2.6.9rc2/include/linux/tty_ldisc.h 2004-09-21 17:21:28.000000000 +0100
@@ -95,6 +95,13 @@
* that line discpline should try to send more characters to the
* low-level driver for transmission. If the line discpline does
* not have any more data to send, it can just return.
+ *
+ * int (*hangup)(struct tty_struct *)
+ *
+ * Called on a hangup. Tells the discipline that it should
+ * cease I/O to the tty driver. Can sleep. The driver should
+ * seek to perform this action quickly but should wait until
+ * any pending driver I/O is completed.
*/
#include <linux/fs.h>
@@ -122,6 +129,7 @@
void (*set_termios)(struct tty_struct *tty, struct termios * old);
unsigned int (*poll)(struct tty_struct *, struct file *,
struct poll_table_struct *);
+ int (*hangup)(struct tty_struct *tty);
/*
* The following routines are called from below.
-
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