tty: Wait interruptibly for tty lock on reopen

commit 0bfd464d3fdd5bb322f9cace4cc47f1796545cf7 upstream.

Allow a signal to interrupt the wait for a tty reopen; eg., if
the tty has starting final close and is waiting for the device to
drain.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index bcc8e1e8bb720996cf73438c67a397362173edca..4d34116842a66f88ec515e1218dd7360a77ccdf1 100644 (file)
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2069,7 +2069,12 @@ retry_open:
 
                if (tty) {
                        mutex_unlock(&tty_mutex);
-                       tty_lock(tty);
+                       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);
@@ -2156,6 +2161,7 @@ retry_open:
        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);

diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c
index 0efcf713b756e5e7eaf95bf7b5f2a744fc7f6dc0..d09293bc0e041417cc15047f84eec0ccd01298eb 100644 (file)
--- a/drivers/tty/tty_mutex.c
+++ b/drivers/tty/tty_mutex.c
@@ -22,6 +22,14 @@ void __lockfunc tty_lock(struct tty_struct *tty)
 }
 EXPORT_SYMBOL(tty_lock);
 
+int tty_lock_interruptible(struct tty_struct *tty)
+{
+       if (WARN(tty->magic != TTY_MAGIC, "L Bad %p\n", tty))
+               return -EIO;
+       tty_kref_get(tty);
+       return mutex_lock_interruptible(&tty->legacy_mutex);
+}
+
 void __lockfunc tty_unlock(struct tty_struct *tty)
 {
        if (tty->magic != TTY_MAGIC) {

diff --git a/include/linux/tty.h b/include/linux/tty.h
index 5e31f1b99037d3cc1d43d2336886a8dcb435808f..6b6e811f45752f627eaa9c4a96a60ef6504c7064 100644 (file)
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -654,6 +654,7 @@ extern long vt_compat_ioctl(struct tty_struct *tty,
 /* tty_mutex.c */
 /* functions for preparation of BKL removal */
 extern void __lockfunc tty_lock(struct tty_struct *tty);
+extern int  tty_lock_interruptible(struct tty_struct *tty);
 extern void __lockfunc tty_unlock(struct tty_struct *tty);
 extern void __lockfunc tty_lock_slave(struct tty_struct *tty);
 extern void __lockfunc tty_unlock_slave(struct tty_struct *tty);