diff options
Diffstat (limited to 'drivers/char/pty.c')
| -rw-r--r-- | drivers/char/pty.c | 335 |
1 files changed, 294 insertions, 41 deletions
diff --git a/drivers/char/pty.c b/drivers/char/pty.c index 76b27932d229..6d4582712b1f 100644 --- a/drivers/char/pty.c +++ b/drivers/char/pty.c @@ -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> @@ -23,26 +25,25 @@ #include <linux/mm.h> #include <linux/init.h> #include <linux/sysctl.h> - -#include <asm/uaccess.h> -#include <asm/system.h> +#include <linux/device.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; } @@ -59,7 +60,7 @@ static void pty_close(struct tty_struct * tty, struct file * filp) set_bit(TTY_OTHER_CLOSED, &tty->flags); #ifdef CONFIG_UNIX98_PTYS if (tty->driver == ptm_driver) - devpts_pty_kill(tty->index); + devpts_pty_kill(tty->link); #endif tty_vhangup(tty->link); } @@ -69,13 +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; @@ -87,7 +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 @@ -100,7 +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; @@ -112,7 +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; } @@ -128,17 +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. @@ -155,21 +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); @@ -182,13 +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; @@ -197,7 +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; @@ -220,13 +223,65 @@ out: 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); +} + +static int pty_install(struct tty_driver *driver, struct tty_struct *tty) { - tty->termios->c_cflag &= ~(CSIZE | PARENB); - tty->termios->c_cflag |= (CS8 | CREAD); + struct tty_struct *o_tty; + int idx = tty->index; + int retval; + + o_tty = alloc_tty_struct(); + if (!o_tty) + return -ENOMEM; + if (!try_module_get(driver->other->owner)) { + /* This cannot in fact currently happen */ + free_tty_struct(o_tty); + return -ENOMEM; + } + initialize_tty_struct(o_tty, driver->other, idx); + + /* We always use new tty termios data so we can do this + the easy way .. */ + retval = tty_init_termios(tty); + if (retval) + goto free_mem_out; + + retval = tty_init_termios(o_tty); + if (retval) { + tty_free_termios(tty); + goto free_mem_out; + } + + /* + * Everything allocated ... set up the o_tty structure. + */ + driver->other->ttys[idx] = o_tty; + tty_driver_kref_get(driver->other); + if (driver->subtype == PTY_TYPE_MASTER) + o_tty->count++; + /* Establish the links in both directions */ + tty->link = o_tty; + o_tty->link = tty; + + tty_driver_kref_get(driver); + tty->count++; + driver->ttys[idx] = tty; + return 0; +free_mem_out: + module_put(o_tty->driver->owner); + free_tty_struct(o_tty); + return -ENOMEM; } + static const struct tty_operations pty_ops = { + .install = pty_install, .open = pty_open, .close = pty_close, .write = pty_write, @@ -329,8 +384,11 @@ 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; + +static struct cdev ptmx_cdev; static struct ctl_table pty_table[] = { { @@ -348,6 +406,7 @@ static struct ctl_table pty_table[] = { .procname = "nr", .maxlen = sizeof(int), .mode = 0444, + .data = &pty_count, .proc_handler = &proc_dointvec, }, { .ctl_name = 0 @@ -388,7 +447,127 @@ static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file, return -ENOIOCTLCMD; } +/** + * ptm_unix98_lookup - find a pty master + * @driver: ptm driver + * @idx: tty index + * + * Look up a pty master device. Called under the tty_mutex for now. + * This provides our locking. + */ + +static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver, + struct inode *ptm_inode, int idx) +{ + struct tty_struct *tty = devpts_get_tty(ptm_inode, idx); + if (tty) + tty = tty->link; + return tty; +} + +/** + * pts_unix98_lookup - find a pty slave + * @driver: pts driver + * @idx: tty index + * + * Look up a pty master device. Called under the tty_mutex for now. + * This provides our locking. + */ + +static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver, + struct inode *pts_inode, int idx) +{ + struct tty_struct *tty = devpts_get_tty(pts_inode, idx); + /* Master must be open before slave */ + if (!tty) + return ERR_PTR(-EIO); + return tty; +} + +static void pty_unix98_shutdown(struct tty_struct *tty) +{ + /* We have our own method as we don't use the tty index */ + kfree(tty->termios); +} + +/* We have no need to install and remove our tty objects as devpts does all + the work for us */ + +static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty) +{ + struct tty_struct *o_tty; + int idx = tty->index; + + o_tty = alloc_tty_struct(); + if (!o_tty) + return -ENOMEM; + if (!try_module_get(driver->other->owner)) { + /* This cannot in fact currently happen */ + free_tty_struct(o_tty); + return -ENOMEM; + } + initialize_tty_struct(o_tty, driver->other, idx); + + tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL); + if (tty->termios == NULL) + goto free_mem_out; + *tty->termios = driver->init_termios; + tty->termios_locked = tty->termios + 1; + + o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL); + if (o_tty->termios == NULL) + goto free_mem_out; + *o_tty->termios = driver->other->init_termios; + o_tty->termios_locked = o_tty->termios + 1; + + tty_driver_kref_get(driver->other); + if (driver->subtype == PTY_TYPE_MASTER) + o_tty->count++; + /* Establish the links in both directions */ + tty->link = o_tty; + o_tty->link = tty; + /* + * All structures have been allocated, so now we install them. + * Failures after this point use release_tty to clean up, so + * there's no need to null out the local pointers. + */ + tty_driver_kref_get(driver); + tty->count++; + pty_count++; + return 0; +free_mem_out: + kfree(o_tty->termios); + module_put(o_tty->driver->owner); + free_tty_struct(o_tty); + kfree(tty->termios); + return -ENOMEM; +} + +static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty) +{ + pty_count--; +} + +static const struct tty_operations ptm_unix98_ops = { + .lookup = ptm_unix98_lookup, + .install = pty_unix98_install, + .remove = pty_unix98_remove, + .open = pty_open, + .close = pty_close, + .write = pty_write, + .write_room = pty_write_room, + .flush_buffer = pty_flush_buffer, + .chars_in_buffer = pty_chars_in_buffer, + .unthrottle = pty_unthrottle, + .set_termios = pty_set_termios, + .ioctl = pty_unix98_ioctl, + .shutdown = pty_unix98_shutdown +}; + static const struct tty_operations pty_unix98_ops = { + .lookup = pts_unix98_lookup, + .install = pty_unix98_install, + .remove = pty_unix98_remove, .open = pty_open, .close = pty_close, .write = pty_write, @@ -397,9 +576,73 @@ static const struct tty_operations pty_unix98_ops = { .chars_in_buffer = pty_chars_in_buffer, .unthrottle = pty_unthrottle, .set_termios = pty_set_termios, - .ioctl = pty_unix98_ioctl + .shutdown = pty_unix98_shutdown }; +/** + * ptmx_open - open a unix 98 pty master + * @inode: inode of device file + * @filp: file pointer to tty + * + * Allocate a unix98 pty master device from the ptmx driver. + * + * Locking: tty_mutex protects the init_dev work. tty->count should + * protect the rest. + * allocated_ptys_lock handles the list of free pty numbers + */ + +static int __ptmx_open(struct inode *inode, struct file *filp) +{ + struct tty_struct *tty; + int retval; + int index; + + nonseekable_open(inode, filp); + + /* find a device that is not in use. */ + index = devpts_new_index(inode); + if (index < 0) + return index; + + mutex_lock(&tty_mutex); + tty = tty_init_dev(ptm_driver, index, 1); + mutex_unlock(&tty_mutex); + + if (IS_ERR(tty)) { + retval = PTR_ERR(tty); + goto out; + } + + set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ + filp->private_data = tty; + file_move(filp, &tty->tty_files); + + retval = devpts_pty_new(inode, tty->link); + if (retval) + goto out1; + + retval = ptm_driver->ops->open(tty, filp); + if (!retval) + return 0; +out1: + tty_release_dev(filp); + return retval; +out: + devpts_kill_index(inode, index); + return retval; +} + +static int ptmx_open(struct inode *inode, struct file *filp) +{ + int ret; + + lock_kernel(); + ret = __ptmx_open(inode, filp); + unlock_kernel(); + return ret; +} + +static struct file_operations ptmx_fops; static void __init unix98_pty_init(void) { @@ -427,7 +670,7 @@ static void __init unix98_pty_init(void) ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM; ptm_driver->other = pts_driver; - tty_set_operations(ptm_driver, &pty_unix98_ops); + tty_set_operations(ptm_driver, &ptm_unix98_ops); pts_driver->owner = THIS_MODULE; pts_driver->driver_name = "pty_slave"; @@ -443,16 +686,26 @@ static void __init unix98_pty_init(void) pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM; pts_driver->other = ptm_driver; - tty_set_operations(pts_driver, &pty_ops); - + 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"); - pty_table[1].data = &ptm_driver->refcount; register_sysctl_table(pty_root_table); + + /* Now create the /dev/ptmx special device */ + tty_default_fops(&ptmx_fops); + ptmx_fops.open = ptmx_open; + + cdev_init(&ptmx_cdev, &ptmx_fops); + if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) || + register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0) + panic("Couldn't register /dev/ptmx driver\n"); + device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx"); } + #else static inline void unix98_pty_init(void) { } #endif |