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tty: Move parts of tty_init_dev into new functions

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Move the 'find-tty' and 'fast-track-open' parts of init_dev() to
separate functions.

Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Sukadev Bhattiprolu 2008-10-13 10:41:51 +01:00 committed by Linus Torvalds
parent d81ed10307
commit 2349970575
1 changed files with 87 additions and 52 deletions
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139
drivers/char/tty_io.c
View file

@ -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) goto fast_track;
if (tty) {
retval = fast_tty_open(tty);
if (retval)
return retval;
*ret_tty = tty;
return 0;
}
/* 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;