4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Peter Hurley <[email protected]> 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 <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/tty/tty_io.c | 8 +++++++- drivers/tty/tty_mutex.c | 8 ++++++++ include/linux/tty.h | 1 + 3 files changed, 16 insertions(+), 1 deletion(-) --- 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); --- a/drivers/tty/tty_mutex.c +++ b/drivers/tty/tty_mutex.c @@ -22,6 +22,14 @@ void __lockfunc tty_lock(struct tty_stru } 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) { --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -654,6 +654,7 @@ extern long vt_compat_ioctl(struct tty_s /* 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);
