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yaml
---
r: 113469
b: refs/heads/master
c: fe9cd96
h: refs/heads/master
i:
  113467: 7a72335
v: v3
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Alan Cox authored and Linus Torvalds committed Oct 13, 2008
1 parent 01386d2 commit 9c2e548
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Showing 2 changed files with 45 additions and 43 deletions.
2 changes: 1 addition & 1 deletion [refs]
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Original file line number Diff line number Diff line change
@@ -1,2 +1,2 @@
---
refs/heads/master: a6f37daa8b892fd29dd71be0de61460a478cb122
refs/heads/master: fe9cd962a62cb5f666cf48b9941d3f3cde134254
86 changes: 44 additions & 42 deletions trunk/drivers/char/pty.c
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Original file line number Diff line number Diff line change
Expand Up @@ -8,10 +8,12 @@
* Added TTY_DO_WRITE_WAKEUP to enable n_tty to send POLL_OUT to
* waiting writers -- Sapan Bhatia <sapan@corewars.org>
*
*
* When reading this code see also fs/devpts. In particular note that the
* driver_data field is used by the devpts side as a binding to the devpts
* inode.
*/

#include <linux/module.h> /* For EXPORT_SYMBOL */
#include <linux/module.h>

#include <linux/errno.h>
#include <linux/interrupt.h>
Expand All @@ -24,26 +26,24 @@
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/device.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/uaccess.h>
#include <linux/bitops.h>
#include <linux/devpts_fs.h>

#include <asm/system.h>

/* These are global because they are accessed in tty_io.c */
#ifdef CONFIG_UNIX98_PTYS
struct tty_driver *ptm_driver;
static struct tty_driver *pts_driver;
#endif

static void pty_close(struct tty_struct * tty, struct file * filp)
static void pty_close(struct tty_struct *tty, struct file *filp)
{
if (!tty)
return;
if (tty->driver->subtype == PTY_TYPE_MASTER) {
if (tty->count > 1)
printk("master pty_close: count = %d!!\n", tty->count);
} else {
BUG_ON(!tty);
if (tty->driver->subtype == PTY_TYPE_MASTER)
WARN_ON(tty->count > 1);
else {
if (tty->count > 2)
return;
}
Expand All @@ -70,13 +70,13 @@ static void pty_close(struct tty_struct * tty, struct file * filp)
* The unthrottle routine is called by the line discipline to signal
* that it can receive more characters. For PTY's, the TTY_THROTTLED
* flag is always set, to force the line discipline to always call the
* unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
* unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
* characters in the queue. This is necessary since each time this
* happens, we need to wake up any sleeping processes that could be
* (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
* for the pty buffer to be drained.
*/
static void pty_unthrottle(struct tty_struct * tty)
static void pty_unthrottle(struct tty_struct *tty)
{
struct tty_struct *o_tty = tty->link;

Expand All @@ -88,7 +88,7 @@ static void pty_unthrottle(struct tty_struct * tty)
}

/*
* WSH 05/24/97: modified to
* WSH 05/24/97: modified to
* (1) use space in tty->flip instead of a shared temp buffer
* The flip buffers aren't being used for a pty, so there's lots
* of space available. The buffer is protected by a per-pty
Expand All @@ -101,7 +101,8 @@ static void pty_unthrottle(struct tty_struct * tty)
* not our partners. We can't just take the other one blindly without
* risking deadlocks.
*/
static int pty_write(struct tty_struct * tty, const unsigned char *buf, int count)
static int pty_write(struct tty_struct *tty, const unsigned char *buf,
int count)
{
struct tty_struct *to = tty->link;
int c;
Expand All @@ -113,7 +114,7 @@ static int pty_write(struct tty_struct * tty, const unsigned char *buf, int coun
if (c > count)
c = count;
to->ldisc.ops->receive_buf(to, buf, NULL, c);

return c;
}

Expand All @@ -129,17 +130,17 @@ static int pty_write_room(struct tty_struct *tty)

/*
* WSH 05/24/97: Modified for asymmetric MASTER/SLAVE behavior
* The chars_in_buffer() value is used by the ldisc select() function
* The chars_in_buffer() value is used by the ldisc select() function
* to hold off writing when chars_in_buffer > WAKEUP_CHARS (== 256).
* The pty driver chars_in_buffer() Master/Slave must behave differently:
*
* The Master side needs to allow typed-ahead commands to accumulate
* while being canonicalized, so we report "our buffer" as empty until
* some threshold is reached, and then report the count. (Any count >
* WAKEUP_CHARS is regarded by select() as "full".) To avoid deadlock
* the count returned must be 0 if no canonical data is available to be
* WAKEUP_CHARS is regarded by select() as "full".) To avoid deadlock
* the count returned must be 0 if no canonical data is available to be
* read. (The N_TTY ldisc.chars_in_buffer now knows this.)
*
*
* The Slave side passes all characters in raw mode to the Master side's
* buffer where they can be read immediately, so in this case we can
* return the true count in the buffer.
Expand All @@ -156,21 +157,22 @@ static int pty_chars_in_buffer(struct tty_struct *tty)
/* The ldisc must report 0 if no characters available to be read */
count = to->ldisc.ops->chars_in_buffer(to);

if (tty->driver->subtype == PTY_TYPE_SLAVE) return count;
if (tty->driver->subtype == PTY_TYPE_SLAVE)
return count;

/* Master side driver ... if the other side's read buffer is less than
/* Master side driver ... if the other side's read buffer is less than
* half full, return 0 to allow writers to proceed; otherwise return
* the count. This leaves a comfortable margin to avoid overflow,
* the count. This leaves a comfortable margin to avoid overflow,
* and still allows half a buffer's worth of typed-ahead commands.
*/
return ((count < N_TTY_BUF_SIZE/2) ? 0 : count);
return (count < N_TTY_BUF_SIZE/2) ? 0 : count;
}

/* Set the lock flag on a pty */
static int pty_set_lock(struct tty_struct *tty, int __user * arg)
static int pty_set_lock(struct tty_struct *tty, int __user *arg)
{
int val;
if (get_user(val,arg))
if (get_user(val, arg))
return -EFAULT;
if (val)
set_bit(TTY_PTY_LOCK, &tty->flags);
Expand All @@ -183,13 +185,13 @@ static void pty_flush_buffer(struct tty_struct *tty)
{
struct tty_struct *to = tty->link;
unsigned long flags;

if (!to)
return;

if (to->ldisc.ops->flush_buffer)
to->ldisc.ops->flush_buffer(to);

if (to->packet) {
spin_lock_irqsave(&tty->ctrl_lock, flags);
tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
Expand All @@ -198,7 +200,7 @@ static void pty_flush_buffer(struct tty_struct *tty)
}
}

static int pty_open(struct tty_struct *tty, struct file * filp)
static int pty_open(struct tty_struct *tty, struct file *filp)
{
int retval = -ENODEV;

Expand All @@ -221,10 +223,11 @@ static int pty_open(struct tty_struct *tty, struct file * filp)
return retval;
}

static void pty_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
static void pty_set_termios(struct tty_struct *tty,
struct ktermios *old_termios)
{
tty->termios->c_cflag &= ~(CSIZE | PARENB);
tty->termios->c_cflag |= (CS8 | CREAD);
tty->termios->c_cflag &= ~(CSIZE | PARENB);
tty->termios->c_cflag |= (CS8 | CREAD);
}

static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
Expand Down Expand Up @@ -254,7 +257,7 @@ static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
tty_free_termios(tty);
goto free_mem_out;
}

/*
* Everything allocated ... set up the o_tty structure.
*/
Expand Down Expand Up @@ -381,9 +384,9 @@ static inline void legacy_pty_init(void) { }
* Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
*/
int pty_limit = NR_UNIX98_PTY_DEFAULT;
static int pty_limit_min = 0;
static int pty_limit_min;
static int pty_limit_max = NR_UNIX98_PTY_MAX;
static int pty_count = 0;
static int pty_count;

static struct cdev ptmx_cdev;

Expand Down Expand Up @@ -537,11 +540,10 @@ static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
pty_count++;
return 0;
free_mem_out:
kfree(o_tty->termios);
pty_unix98_shutdown(o_tty);
module_put(o_tty->driver->owner);
free_tty_struct(o_tty);
kfree(tty->termios_locked);
kfree(tty->termios);
pty_unix98_shutdown(tty);
free_tty_struct(tty);
module_put(driver->owner);
return -ENOMEM;
Expand Down Expand Up @@ -691,13 +693,13 @@ static void __init unix98_pty_init(void)
TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
pts_driver->other = ptm_driver;
tty_set_operations(pts_driver, &pty_unix98_ops);

if (tty_register_driver(ptm_driver))
panic("Couldn't register Unix98 ptm driver");
if (tty_register_driver(pts_driver))
panic("Couldn't register Unix98 pts driver");

register_sysctl_table(pty_root_table);
register_sysctl_table(pty_root_table);

/* Now create the /dev/ptmx special device */
tty_default_fops(&ptmx_fops);
Expand Down

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