diff options
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/tty_io.c | 139 |
1 files changed, 87 insertions, 52 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index fdcc43c8ef3..a5408496d30 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -1204,6 +1204,80 @@ static void tty_line_name(struct tty_driver *driver, int index, char *p) sprintf(p, "%s%d", driver->name, index + driver->name_base); } +/* + * find_tty() - find an existing tty, if any + * @driver: the driver for the tty + * @idx: the minor number + * + * Return the tty, if found or ERR_PTR() otherwise. + * + * Locking: tty_mutex must be held. If tty is found, the mutex must + * be held until the 'fast-open' is also done. + */ +struct tty_struct *find_tty(struct tty_driver *driver, int idx) +{ + struct tty_struct *tty; + + /* check whether we're reopening an existing tty */ + if (driver->flags & TTY_DRIVER_DEVPTS_MEM) { + tty = devpts_get_tty(idx); + /* + * If we don't have a tty here on a slave open, it's because + * the master already started the close process and there's + * no relation between devpts file and tty anymore. + */ + if (!tty && driver->subtype == PTY_TYPE_SLAVE) + return ERR_PTR(-EIO); + + /* + * tty is safe on because we are called with tty_mutex held + * and release_dev() won't change tty->count or tty->flags + * without grabbing tty_mutex. + */ + if (tty && driver->subtype == PTY_TYPE_MASTER) + tty = tty->link; + } else + tty = driver->ttys[idx]; + return tty; +} + +/* + * fast_tty_open() - fast re-open of an open tty + * @tty - the tty to open + * + * Return 0 on success, -errno on error. + * + * Locking: tty_mutex must be held from the time the tty was found + * till this open completes. + */ +static int fast_tty_open(struct tty_struct *tty) +{ + struct tty_driver *driver = tty->driver; + + if (test_bit(TTY_CLOSING, &tty->flags)) + return -EIO; + + if (driver->type == TTY_DRIVER_TYPE_PTY && + driver->subtype == PTY_TYPE_MASTER) { + /* + * special case for PTY masters: only one open permitted, + * and the slave side open count is incremented as well. + */ + if (tty->count) + return -EIO; + + tty->link->count++; + } + tty->count++; + tty->driver = driver; /* N.B. why do this every time?? */ + + /* FIXME */ + if (!test_bit(TTY_LDISC, &tty->flags)) + printk(KERN_ERR "fast_tty_open: no ldisc\n"); + + return 0; +} + /** * tty_init_dev - initialise a tty device * @driver: tty driver we are opening a device on @@ -1238,29 +1312,21 @@ int tty_init_dev(struct tty_driver *driver, int idx, int retval = 0; /* check whether we're reopening an existing tty */ - if (driver->flags & TTY_DRIVER_DEVPTS_MEM) { - tty = devpts_get_tty(idx); - /* - * If we don't have a tty here on a slave open, it's because - * the master already started the close process and there's - * no relation between devpts file and tty anymore. - */ - if (!tty && driver->subtype == PTY_TYPE_SLAVE) { - retval = -EIO; - goto end_init; - } - /* - * It's safe from now on because tty_init_dev() is called with - * tty_mutex held and tty_release_dev() won't change tty->count - * or tty->flags without having to grab tty_mutex - */ - if (tty && driver->subtype == PTY_TYPE_MASTER) - tty = tty->link; - } else { - tty = driver->ttys[idx]; + tty = find_tty(driver, idx); + if (IS_ERR(tty)) { + retval = PTR_ERR(tty); + goto end_init; + } + + if (tty) { + retval = fast_tty_open(tty); + if (retval) + return retval; + *ret_tty = tty; + return 0; } - if (tty) goto fast_track; + /* Check if pty master is being opened multiple times */ if (driver->subtype == PTY_TYPE_MASTER && (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) { retval = -EIO; @@ -1400,37 +1466,6 @@ int tty_init_dev(struct tty_driver *driver, int idx, if (retval) goto release_mem_out; - goto success; - - /* - * This fast open can be used if the tty is already open. - * No memory is allocated, and the only failures are from - * attempting to open a closing tty or attempting multiple - * opens on a pty master. - */ -fast_track: - if (test_bit(TTY_CLOSING, &tty->flags)) { - retval = -EIO; - goto end_init; - } - if (driver->type == TTY_DRIVER_TYPE_PTY && - driver->subtype == PTY_TYPE_MASTER) { - /* - * special case for PTY masters: only one open permitted, - * and the slave side open count is incremented as well. - */ - if (tty->count) { - retval = -EIO; - goto end_init; - } - tty->link->count++; - } - tty->count++; - tty->driver = driver; /* N.B. why do this every time?? */ - - /* FIXME */ - if (!test_bit(TTY_LDISC, &tty->flags)) - printk(KERN_ERR "tty_init_dev but no ldisc\n"); success: *ret_tty = tty; |