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TTY: extract driver lookup from tty_open 

The error handling in tty_open became unbearable. There were many
errors fixed recently. Extract the tty driver lookup from tty_open to
a separate function. This reduces the fail paths significantly and
makes tty_open more readable.

In the next patch we will move the fail path handling to the end of
the function.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Jiri Slaby 2011-11-09 21:33:20 +01:00 committed by Greg Kroah-Hartman
parent b82154ac37
commit 5b5e70408f
1 changed files with 55 additions and 38 deletions
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93
drivers/tty/tty_io.c
View File

@ -1823,6 +1823,53 @@ static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
return tty;
}
/**
* tty_lookup_driver - lookup a tty driver for a given device file
* @device: device number
* @filp: file pointer to tty
* @noctty: set if the device should not become a controlling tty
* @index: index for the device in the @return driver
* @return: driver for this inode (with increased refcount)
*
* If @return is not erroneous, the caller is responsible to decrement the
* refcount by tty_driver_kref_put.
*
* Locking: tty_mutex protects get_tty_driver
*/
static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
int *noctty, int *index)
{
struct tty_driver *driver;
#ifdef CONFIG_VT
if (device == MKDEV(TTY_MAJOR, 0)) {
extern struct tty_driver *console_driver;
driver = tty_driver_kref_get(console_driver);
*index = fg_console;
*noctty = 1;
return driver;
}
#endif
if (device == MKDEV(TTYAUX_MAJOR, 1)) {
struct tty_driver *console_driver = console_device(index);
if (console_driver) {
driver = tty_driver_kref_get(console_driver);
if (driver) {
/* Don't let /dev/console block */
filp->f_flags |= O_NONBLOCK;
*noctty = 1;
return driver;
}
}
return ERR_PTR(-ENODEV);
}
driver = get_tty_driver(device, index);
if (!driver)
return ERR_PTR(-ENODEV);
return driver;
}
/**
* tty_open - open a tty device
* @inode: inode of device file
@ -1839,7 +1886,7 @@ static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
* The termios state of a pty is reset on first open so that
* settings don't persist across reuse.
*
* Locking: tty_mutex protects tty, get_tty_driver and tty_init_dev work.
* Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
* tty->count should protect the rest.
* ->siglock protects ->signal/->sighand
*/
@ -1873,47 +1920,17 @@ static int tty_open(struct inode *inode, struct file *filp)
mutex_unlock(&tty_mutex);
tty_free_file(filp);
return PTR_ERR(tty);
} else if (tty)
goto got_driver;
#ifdef CONFIG_VT
if (device == MKDEV(TTY_MAJOR, 0)) {
extern struct tty_driver *console_driver;
driver = tty_driver_kref_get(console_driver);
index = fg_console;
noctty = 1;
goto got_driver;
}
#endif
if (device == MKDEV(TTYAUX_MAJOR, 1)) {
struct tty_driver *console_driver = console_device(&index);
if (console_driver) {
driver = tty_driver_kref_get(console_driver);
if (driver) {
/* Don't let /dev/console block */
filp->f_flags |= O_NONBLOCK;
noctty = 1;
goto got_driver;
}
} else if (!tty) {
driver = tty_lookup_driver(device, filp, &noctty, &index);
if (IS_ERR(driver)) {
tty_unlock();
mutex_unlock(&tty_mutex);
tty_free_file(filp);
return PTR_ERR(driver);
}
tty_unlock();
mutex_unlock(&tty_mutex);
tty_free_file(filp);
return -ENODEV;
}
driver = get_tty_driver(device, &index);
if (!driver) {
tty_unlock();
mutex_unlock(&tty_mutex);
tty_free_file(filp);
return -ENODEV;
}
got_driver:
if (!tty) {
/* check whether we're reopening an existing tty */
tty = tty_driver_lookup_tty(driver, inode, index);
if (IS_ERR(tty)) {
tty_unlock();
mutex_unlock(&tty_mutex);