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author | Peter Hurley <peter@hurleysoftware.com> | 2016-01-09 21:13:53 -0800 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-01-27 14:28:20 -0800 |
commit | d6203d0c7b738d7ce75d5629b72640b489487cfa (patch) | |
tree | 4bf1998b4b5328433d57adae339fb6d5d5d98643 /drivers/tty/tty_io.c | |
parent | 11e1d4aa4da1d0572b00f040ae91da85d3474f4a (diff) | |
download | linux-stable-d6203d0c7b738d7ce75d5629b72640b489487cfa.tar.gz linux-stable-d6203d0c7b738d7ce75d5629b72640b489487cfa.tar.bz2 linux-stable-d6203d0c7b738d7ce75d5629b72640b489487cfa.zip |
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: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/tty_io.c')
-rw-r--r-- | drivers/tty/tty_io.c | 120 |
1 files changed, 67 insertions, 53 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 741a0d7f51ce..524703a7df2b 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1995,6 +1995,69 @@ static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp, } /** + * tty_open_by_driver - open a tty device + * @device: dev_t of device to open + * @inode: inode of device file + * @filp: file pointer to tty + * + * Performs the driver lookup, checks for a reopen, or otherwise + * performs the first-time tty initialization. + * + * Returns the locked initialized or re-opened &tty_struct + * + * Claims the global tty_mutex to serialize: + * - concurrent first-time tty initialization + * - concurrent tty driver removal w/ lookup + * - concurrent tty removal from driver table + */ +static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode, + struct file *filp) +{ + struct tty_struct *tty; + struct tty_driver *driver = NULL; + int index = -1; + int retval; + + mutex_lock(&tty_mutex); + driver = tty_lookup_driver(device, filp, &index); + if (IS_ERR(driver)) { + mutex_unlock(&tty_mutex); + return ERR_CAST(driver); + } + + /* check whether we're reopening an existing tty */ + tty = tty_driver_lookup_tty(driver, inode, index); + if (IS_ERR(tty)) { + mutex_unlock(&tty_mutex); + goto out; + } + + if (tty) { + mutex_unlock(&tty_mutex); + retval = tty_lock_interruptible(tty); + if (retval) { + if (retval == -EINTR) + retval = -ERESTARTSYS; + tty = ERR_PTR(retval); + goto out; + } + /* safe to drop the kref from tty_driver_lookup_tty() */ + tty_kref_put(tty); + retval = tty_reopen(tty); + if (retval < 0) { + tty_unlock(tty); + tty = ERR_PTR(retval); + } + } else { /* Returns with the tty_lock held for now */ + tty = tty_init_dev(driver, index); + mutex_unlock(&tty_mutex); + } +out: + tty_driver_kref_put(driver); + return tty; +} + +/** * tty_open - open a tty device * @inode: inode of device file * @filp: file pointer to tty @@ -2022,8 +2085,6 @@ static int tty_open(struct inode *inode, struct file *filp) { struct tty_struct *tty; int noctty, retval; - struct tty_driver *driver = NULL; - int index; dev_t device = inode->i_rdev; unsigned saved_flags = filp->f_flags; @@ -2034,53 +2095,15 @@ retry_open: if (retval) return -ENOMEM; - index = -1; - retval = 0; - tty = tty_open_current_tty(device, filp); - if (!tty) { - mutex_lock(&tty_mutex); - driver = tty_lookup_driver(device, filp, &index); - if (IS_ERR(driver)) { - retval = PTR_ERR(driver); - goto err_unlock; - } - - /* check whether we're reopening an existing tty */ - tty = tty_driver_lookup_tty(driver, inode, index); - if (IS_ERR(tty)) { - retval = PTR_ERR(tty); - goto err_unlock; - } - - if (tty) { - mutex_unlock(&tty_mutex); - retval = tty_lock_interruptible(tty); - if (retval) { - if (retval == -EINTR) - retval = -ERESTARTSYS; - goto err_unref; - } - /* safe to drop the kref from tty_driver_lookup_tty() */ - tty_kref_put(tty); - retval = tty_reopen(tty); - if (retval < 0) { - tty_unlock(tty); - tty = ERR_PTR(retval); - } - } else { /* Returns with the tty_lock held for now */ - tty = tty_init_dev(driver, index); - mutex_unlock(&tty_mutex); - } - - tty_driver_kref_put(driver); - } + if (!tty) + tty = tty_open_by_driver(device, inode, filp); if (IS_ERR(tty)) { + tty_free_file(filp); retval = PTR_ERR(tty); if (retval != -EAGAIN || signal_pending(current)) - goto err_file; - tty_free_file(filp); + return retval; schedule(); goto retry_open; } @@ -2151,15 +2174,6 @@ retry_open: read_unlock(&tasklist_lock); tty_unlock(tty); 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; } |