tty: push the BKL down into the handlers a bit

Start trying to untangle the remaining BKL mess

Updated to fix missing unlock_kernel noted by Dan Carpenter

Signed-off-by: Alan "I must be out of my tree" Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 95 insertions, 63 deletions

diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index d86c0bc05c1c..385c44b3034f 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -659,7 +659,7 @@ static int __ptmx_open(struct inode *inode, struct file *filp)
         if (!retval)
                 return 0;
 out1:
-        tty_release_dev(filp);
+        tty_release(inode, filp);
         return retval;
 out:
         devpts_kill_index(inode, index);
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 59499ee0fe6a..1e2413093615 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -142,7 +142,6 @@ ssize_t redirected_tty_write(struct file *, const char __user *,
                                                         size_t, loff_t *);
 static unsigned int tty_poll(struct file *, poll_table *);
 static int tty_open(struct inode *, struct file *);
-static int tty_release(struct inode *, struct file *);
 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
 #ifdef CONFIG_COMPAT
 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
@@ -1017,14 +1016,16 @@ out:
 
 void tty_write_message(struct tty_struct *tty, char *msg)
 {
-        lock_kernel();
         if (tty) {
                 mutex_lock(&tty->atomic_write_lock);
-                if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags))
+                lock_kernel();
+                if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) {
+                        unlock_kernel();
                         tty->ops->write(tty, msg, strlen(msg));
+                } else
+                        unlock_kernel();
                 tty_write_unlock(tty);
         }
-        unlock_kernel();
         return;
 }
 
@@ -1202,14 +1203,21 @@ static int tty_driver_install_tty(struct tty_driver *driver,
                                                 struct tty_struct *tty)
 {
         int idx = tty->index;
+        int ret;
 
-        if (driver->ops->install)
-                return driver->ops->install(driver, tty);
+        if (driver->ops->install) {
+                lock_kernel();
+                ret = driver->ops->install(driver, tty);
+                unlock_kernel();
+                return ret;
+        }
 
         if (tty_init_termios(tty) == 0) {
+                lock_kernel();
                 tty_driver_kref_get(driver);
                 tty->count++;
                 driver->ttys[idx] = tty;
+                unlock_kernel();
                 return 0;
         }
         return -ENOMEM;
@@ -1302,10 +1310,14 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
         struct tty_struct *tty;
         int retval;
 
+        lock_kernel();
         /* Check if pty master is being opened multiple times */
         if (driver->subtype == PTY_TYPE_MASTER &&
-                (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok)
+                (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
+                unlock_kernel();
                 return ERR_PTR(-EIO);
+        }
+        unlock_kernel();
 
         /*
          * First time open is complex, especially for PTY devices.
@@ -1335,8 +1347,9 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
          * If we fail here just call release_tty to clean up.  No need
          * to decrement the use counts, as release_tty doesn't care.
          */
-
+        lock_kernel();
         retval = tty_ldisc_setup(tty, tty->link);
+        unlock_kernel();
         if (retval)
                 goto release_mem_out;
         return tty;
@@ -1350,7 +1363,9 @@ release_mem_out:
         if (printk_ratelimit())
                 printk(KERN_INFO "tty_init_dev: ldisc open failed, "
                                  "clearing slot %d\n", idx);
+        lock_kernel();
         release_tty(tty, idx);
+        unlock_kernel();
         return ERR_PTR(retval);
 }
 
@@ -1464,7 +1479,17 @@ static void release_tty(struct tty_struct *tty, int idx)
         tty_kref_put(tty);
 }
 
-/*
+/**
+ *      tty_release             -       vfs callback for close
+ *      @inode: inode of tty
+ *      @filp: file pointer for handle to tty
+ *
+ *      Called the last time each file handle is closed that references
+ *      this tty. There may however be several such references.
+ *
+ *      Locking:
+ *              Takes bkl. See tty_release_dev
+ *
  * Even releasing the tty structures is a tricky business.. We have
  * to be very careful that the structures are all released at the
  * same time, as interrupts might otherwise get the wrong pointers.
@@ -1472,20 +1497,20 @@ static void release_tty(struct tty_struct *tty, int idx)
  * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
  * lead to double frees or releasing memory still in use.
  */
-void tty_release_dev(struct file *filp)
+
+int tty_release(struct inode *inode, struct file *filp)
 {
         struct tty_struct *tty, *o_tty;
         int     pty_master, tty_closing, o_tty_closing, do_sleep;
         int     devpts;
         int     idx;
         char    buf[64];
-        struct  inode *inode;
 
-        inode = filp->f_path.dentry->d_inode;
         tty = (struct tty_struct *)filp->private_data;
         if (tty_paranoia_check(tty, inode, "tty_release_dev"))
-                return;
+                return 0;
 
+        lock_kernel();
         check_tty_count(tty, "tty_release_dev");
 
         tty_fasync(-1, filp, 0);
@@ -1500,19 +1525,22 @@ void tty_release_dev(struct file *filp)
         if (idx < 0 || idx >= tty->driver->num) {
                 printk(KERN_DEBUG "tty_release_dev: bad idx when trying to "
                                   "free (%s)\n", tty->name);
-                return;
+                unlock_kernel();
+                return 0;
         }
         if (!devpts) {
                 if (tty != tty->driver->ttys[idx]) {
+                        unlock_kernel();
                         printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty "
                                "for (%s)\n", idx, tty->name);
-                        return;
+                        return 0;
                 }
                 if (tty->termios != tty->driver->termios[idx]) {
+                        unlock_kernel();
                         printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios "
                                "for (%s)\n",
                                idx, tty->name);
-                        return;
+                        return 0;
                 }
         }
 #endif
@@ -1526,26 +1554,30 @@ void tty_release_dev(struct file *filp)
         if (tty->driver->other &&
              !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
                 if (o_tty != tty->driver->other->ttys[idx]) {
+                        unlock_kernel();
                         printk(KERN_DEBUG "tty_release_dev: other->table[%d] "
                                           "not o_tty for (%s)\n",
                                idx, tty->name);
-                        return;
+                        return 0 ;
                 }
                 if (o_tty->termios != tty->driver->other->termios[idx]) {
+                        unlock_kernel();
                         printk(KERN_DEBUG "tty_release_dev: other->termios[%d] "
                                           "not o_termios for (%s)\n",
                                idx, tty->name);
-                        return;
+                        return 0;
                 }
                 if (o_tty->link != tty) {
+                        unlock_kernel();
                         printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n");
-                        return;
+                        return 0;
                 }
         }
 #endif
         if (tty->ops->close)
                 tty->ops->close(tty, filp);
 
+        unlock_kernel();
         /*
          * Sanity check: if tty->count is going to zero, there shouldn't be
          * any waiters on tty->read_wait or tty->write_wait.  We test the
@@ -1568,6 +1600,7 @@ void tty_release_dev(struct file *filp)
                    opens on /dev/tty */
 
                 mutex_lock(&tty_mutex);
+                lock_kernel();
                 tty_closing = tty->count <= 1;
                 o_tty_closing = o_tty &&
                         (o_tty->count <= (pty_master ? 1 : 0));
@@ -1598,6 +1631,7 @@ void tty_release_dev(struct file *filp)
 
                 printk(KERN_WARNING "tty_release_dev: %s: read/write wait queue "
                                     "active!\n", tty_name(tty, buf));
+                unlock_kernel();
                 mutex_unlock(&tty_mutex);
                 schedule();
         }
@@ -1661,8 +1695,10 @@ void tty_release_dev(struct file *filp)
         mutex_unlock(&tty_mutex);
 
         /* check whether both sides are closing ... */
-        if (!tty_closing || (o_tty && !o_tty_closing))
-                return;
+        if (!tty_closing || (o_tty && !o_tty_closing)) {
+                unlock_kernel();
+                return 0;
+        }
 
 #ifdef TTY_DEBUG_HANGUP
         printk(KERN_DEBUG "freeing tty structure...");
@@ -1680,10 +1716,12 @@ void tty_release_dev(struct file *filp)
         /* Make this pty number available for reallocation */
         if (devpts)
                 devpts_kill_index(inode, idx);
+        unlock_kernel();
+        return 0;
 }
 
 /**
- *      __tty_open              -       open a tty device
+ *      tty_open                -       open a tty device
  *      @inode: inode of device file
  *      @filp: file pointer to tty
  *
@@ -1703,7 +1741,7 @@ void tty_release_dev(struct file *filp)
  *               ->siglock protects ->signal/->sighand
  */
 
-static int __tty_open(struct inode *inode, struct file *filp)
+static int tty_open(struct inode *inode, struct file *filp)
 {
         struct tty_struct *tty = NULL;
         int noctty, retval;
@@ -1720,10 +1758,12 @@ retry_open:
         retval = 0;
 
         mutex_lock(&tty_mutex);
+        lock_kernel();
 
         if (device == MKDEV(TTYAUX_MAJOR, 0)) {
                 tty = get_current_tty();
                 if (!tty) {
+                        unlock_kernel();
                         mutex_unlock(&tty_mutex);
                         return -ENXIO;
                 }
@@ -1755,12 +1795,14 @@ retry_open:
                                 goto got_driver;
                         }
                 }
+                unlock_kernel();
                 mutex_unlock(&tty_mutex);
                 return -ENODEV;
         }
 
         driver = get_tty_driver(device, &index);
         if (!driver) {
+                unlock_kernel();
                 mutex_unlock(&tty_mutex);
                 return -ENODEV;
         }
@@ -1770,6 +1812,7 @@ got_driver:
                 tty = tty_driver_lookup_tty(driver, inode, index);
 
                 if (IS_ERR(tty)) {
+                        unlock_kernel();
                         mutex_unlock(&tty_mutex);
                         return PTR_ERR(tty);
                 }
@@ -1784,8 +1827,10 @@ got_driver:
 
         mutex_unlock(&tty_mutex);
         tty_driver_kref_put(driver);
-        if (IS_ERR(tty))
+        if (IS_ERR(tty)) {
+                unlock_kernel();
                 return PTR_ERR(tty);
+        }
 
         filp->private_data = tty;
         file_move(filp, &tty->tty_files);
@@ -1813,11 +1858,15 @@ got_driver:
                 printk(KERN_DEBUG "error %d in opening %s...", retval,
                        tty->name);
 #endif
-                tty_release_dev(filp);
-                if (retval != -ERESTARTSYS)
+                tty_release(inode, filp);
+                if (retval != -ERESTARTSYS) {
+                        unlock_kernel();
                         return retval;
-                if (signal_pending(current))
+                }
+                if (signal_pending(current)) {
+                        unlock_kernel();
                         return retval;
+                }
                 schedule();
                 /*
                  * Need to reset f_op in case a hangup happened.
@@ -1826,8 +1875,11 @@ got_driver:
                         filp->f_op = &tty_fops;
                 goto retry_open;
         }
+        unlock_kernel();
+
 
         mutex_lock(&tty_mutex);
+        lock_kernel();
         spin_lock_irq(&current->sighand->siglock);
         if (!noctty &&
             current->signal->leader &&
@@ -1835,44 +1887,13 @@ got_driver:
             tty->session == NULL)
                 __proc_set_tty(current, tty);
         spin_unlock_irq(&current->sighand->siglock);
+        unlock_kernel();
         mutex_unlock(&tty_mutex);
         return 0;
 }
 
-/* BKL pushdown: scary code avoidance wrapper */
-static int tty_open(struct inode *inode, struct file *filp)
-{
-        int ret;
-
-        lock_kernel();
-        ret = __tty_open(inode, filp);
-        unlock_kernel();
-        return ret;
-}
 
 
-
-
-/**
- *      tty_release             -       vfs callback for close
- *      @inode: inode of tty
- *      @filp: file pointer for handle to tty
- *
- *      Called the last time each file handle is closed that references
- *      this tty. There may however be several such references.
- *
- *      Locking:
- *              Takes bkl. See tty_release_dev
- */
-
-static int tty_release(struct inode *inode, struct file *filp)
-{
-        lock_kernel();
-        tty_release_dev(filp);
-        unlock_kernel();
-        return 0;
-}
-
 /**
  *      tty_poll        -       check tty status
  *      @filp: file being polled
@@ -2317,9 +2338,7 @@ static int tiocsetd(struct tty_struct *tty, int __user *p)
         if (get_user(ldisc, p))
                 return -EFAULT;
 
-        lock_kernel();
         ret = tty_set_ldisc(tty, ldisc);
-        unlock_kernel();
 
         return ret;
 }
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index feb55075819b..d914e77f7f01 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -34,6 +34,8 @@
 #include <linux/vt_kern.h>
 #include <linux/selection.h>
 
+#include <linux/smp_lock.h>     /* For the moment */
+
 #include <linux/kmod.h>
 #include <linux/nsproxy.h>
 
@@ -545,6 +547,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
         if (IS_ERR(new_ldisc))
                 return PTR_ERR(new_ldisc);
 
+        lock_kernel();
         /*
          *      We need to look at the tty locking here for pty/tty pairs
          *      when both sides try to change in parallel.
@@ -558,6 +561,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
          */
 
         if (tty->ldisc->ops->num == ldisc) {
+                unlock_kernel();
                 tty_ldisc_put(new_ldisc);
                 return 0;
         }
@@ -569,6 +573,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
         tty_wait_until_sent(tty, 0);
 
+        unlock_kernel();
         mutex_lock(&tty->ldisc_mutex);
 
         /*
@@ -582,6 +587,9 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
                         test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0);
                 mutex_lock(&tty->ldisc_mutex);
         }
+
+        lock_kernel();
+
         set_bit(TTY_LDISC_CHANGING, &tty->flags);
 
         /*
@@ -592,6 +600,8 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
         tty->receive_room = 0;
 
         o_ldisc = tty->ldisc;
+
+        unlock_kernel();
         /*
          *      Make sure we don't change while someone holds a
          *      reference to the line discipline. The TTY_LDISC bit
@@ -617,12 +627,14 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
         flush_scheduled_work();
 
         mutex_lock(&tty->ldisc_mutex);
+        lock_kernel();
         if (test_bit(TTY_HUPPED, &tty->flags)) {
                 /* We were raced by the hangup method. It will have stomped
                    the ldisc data and closed the ldisc down */
                 clear_bit(TTY_LDISC_CHANGING, &tty->flags);
                 mutex_unlock(&tty->ldisc_mutex);
                 tty_ldisc_put(new_ldisc);
+                unlock_kernel();
                 return -EIO;
         }
 
@@ -664,6 +676,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
         if (o_work)
                 schedule_delayed_work(&o_tty->buf.work, 1);
         mutex_unlock(&tty->ldisc_mutex);
+        unlock_kernel();
         return retval;
 }
 
diff --git a/include/linux/tty.h b/include/linux/tty.h
index e6da667ba34d..405a9035fe40 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -449,7 +449,7 @@ extern void initialize_tty_struct(struct tty_struct *tty,
                 struct tty_driver *driver, int idx);
 extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
                                                                 int first_ok);
-extern void tty_release_dev(struct file *filp);
+extern int tty_release(struct inode *inode, struct file *filp);
 extern int tty_init_termios(struct tty_struct *tty);
 
 extern struct tty_struct *tty_pair_get_tty(struct tty_struct *tty);