Commit d6203d0c authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman

tty: Refactor tty_open()

Extract the driver lookup and reopen-or-initialize logic into helper
function tty_open_by_driver(). No functional change.
Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 11e1d4aa
...@@ -1995,62 +1995,41 @@ static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp, ...@@ -1995,62 +1995,41 @@ static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
} }
/** /**
* tty_open - open a tty device * tty_open_by_driver - open a tty device
* @device: dev_t of device to open
* @inode: inode of device file * @inode: inode of device file
* @filp: file pointer to tty * @filp: file pointer to tty
* *
* tty_open and tty_release keep up the tty count that contains the * Performs the driver lookup, checks for a reopen, or otherwise
* number of opens done on a tty. We cannot use the inode-count, as * performs the first-time tty initialization.
* different inodes might point to the same tty.
*
* Open-counting is needed for pty masters, as well as for keeping
* track of serial lines: DTR is dropped when the last close happens.
* (This is not done solely through tty->count, now. - Ted 1/27/92)
* *
* The termios state of a pty is reset on first open so that * Returns the locked initialized or re-opened &tty_struct
* settings don't persist across reuse.
* *
* Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev. * Claims the global tty_mutex to serialize:
* tty->count should protect the rest. * - concurrent first-time tty initialization
* ->siglock protects ->signal/->sighand * - concurrent tty driver removal w/ lookup
* * - concurrent tty removal from driver table
* Note: the tty_unlock/lock cases without a ref are only safe due to
* tty_mutex
*/ */
static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode,
static int tty_open(struct inode *inode, struct file *filp) struct file *filp)
{ {
struct tty_struct *tty; struct tty_struct *tty;
int noctty, retval;
struct tty_driver *driver = NULL; struct tty_driver *driver = NULL;
int index; int index = -1;
dev_t device = inode->i_rdev; int retval;
unsigned saved_flags = filp->f_flags;
nonseekable_open(inode, filp);
retry_open:
retval = tty_alloc_file(filp);
if (retval)
return -ENOMEM;
index = -1;
retval = 0;
tty = tty_open_current_tty(device, filp);
if (!tty) {
mutex_lock(&tty_mutex); mutex_lock(&tty_mutex);
driver = tty_lookup_driver(device, filp, &index); driver = tty_lookup_driver(device, filp, &index);
if (IS_ERR(driver)) { if (IS_ERR(driver)) {
retval = PTR_ERR(driver); mutex_unlock(&tty_mutex);
goto err_unlock; return ERR_CAST(driver);
} }
/* check whether we're reopening an existing tty */ /* check whether we're reopening an existing tty */
tty = tty_driver_lookup_tty(driver, inode, index); tty = tty_driver_lookup_tty(driver, inode, index);
if (IS_ERR(tty)) { if (IS_ERR(tty)) {
retval = PTR_ERR(tty); mutex_unlock(&tty_mutex);
goto err_unlock; goto out;
} }
if (tty) { if (tty) {
...@@ -2059,7 +2038,8 @@ static int tty_open(struct inode *inode, struct file *filp) ...@@ -2059,7 +2038,8 @@ static int tty_open(struct inode *inode, struct file *filp)
if (retval) { if (retval) {
if (retval == -EINTR) if (retval == -EINTR)
retval = -ERESTARTSYS; retval = -ERESTARTSYS;
goto err_unref; tty = ERR_PTR(retval);
goto out;
} }
/* safe to drop the kref from tty_driver_lookup_tty() */ /* safe to drop the kref from tty_driver_lookup_tty() */
tty_kref_put(tty); tty_kref_put(tty);
...@@ -2072,15 +2052,58 @@ static int tty_open(struct inode *inode, struct file *filp) ...@@ -2072,15 +2052,58 @@ static int tty_open(struct inode *inode, struct file *filp)
tty = tty_init_dev(driver, index); tty = tty_init_dev(driver, index);
mutex_unlock(&tty_mutex); mutex_unlock(&tty_mutex);
} }
out:
tty_driver_kref_put(driver); tty_driver_kref_put(driver);
} return tty;
}
/**
* tty_open - open a tty device
* @inode: inode of device file
* @filp: file pointer to tty
*
* tty_open and tty_release keep up the tty count that contains the
* number of opens done on a tty. We cannot use the inode-count, as
* different inodes might point to the same tty.
*
* Open-counting is needed for pty masters, as well as for keeping
* track of serial lines: DTR is dropped when the last close happens.
* (This is not done solely through tty->count, now. - Ted 1/27/92)
*
* The termios state of a pty is reset on first open so that
* settings don't persist across reuse.
*
* Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
* tty->count should protect the rest.
* ->siglock protects ->signal/->sighand
*
* Note: the tty_unlock/lock cases without a ref are only safe due to
* tty_mutex
*/
static int tty_open(struct inode *inode, struct file *filp)
{
struct tty_struct *tty;
int noctty, retval;
dev_t device = inode->i_rdev;
unsigned saved_flags = filp->f_flags;
nonseekable_open(inode, filp);
retry_open:
retval = tty_alloc_file(filp);
if (retval)
return -ENOMEM;
tty = tty_open_current_tty(device, filp);
if (!tty)
tty = tty_open_by_driver(device, inode, filp);
if (IS_ERR(tty)) { if (IS_ERR(tty)) {
tty_free_file(filp);
retval = PTR_ERR(tty); retval = PTR_ERR(tty);
if (retval != -EAGAIN || signal_pending(current)) if (retval != -EAGAIN || signal_pending(current))
goto err_file; return retval;
tty_free_file(filp);
schedule(); schedule();
goto retry_open; goto retry_open;
} }
...@@ -2151,15 +2174,6 @@ static int tty_open(struct inode *inode, struct file *filp) ...@@ -2151,15 +2174,6 @@ static int tty_open(struct inode *inode, struct file *filp)
read_unlock(&tasklist_lock); read_unlock(&tasklist_lock);
tty_unlock(tty); tty_unlock(tty);
return 0; return 0;
err_unlock:
mutex_unlock(&tty_mutex);
err_unref:
/* after locks to avoid deadlock */
if (!IS_ERR_OR_NULL(driver))
tty_driver_kref_put(driver);
err_file:
tty_free_file(filp);
return retval;
} }
......
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