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authorPeter Hurley <peter@hurleysoftware.com>2016-01-09 21:13:44 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-01-26 23:17:54 -0800
commit0bfd464d3fdd5bb322f9cace4cc47f1796545cf7 (patch)
tree39464f856fd4dc6b58c31e2cfbbbb882ce3b7ec1
parent92e963f50fc74041b5e9e744c330dca48e04f08d (diff)
tty: Wait interruptibly for tty lock on reopen
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> Cc: stable <stable@vger.kernel.org> # 4.4 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/tty/tty_io.c8
-rw-r--r--drivers/tty/tty_mutex.c8
-rw-r--r--include/linux/tty.h1
3 files changed, 16 insertions, 1 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 892c92354745..765935b144d6 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2065,7 +2065,12 @@ 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);
@@ -2152,6 +2157,7 @@ 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 77703a391207..d2f3c4cd697f 100644
--- a/drivers/tty/tty_mutex.c
+++ b/drivers/tty/tty_mutex.c
@@ -19,6 +19,14 @@ 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 (WARN(tty->magic != TTY_MAGIC, "U Bad %p\n", tty))
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 2fd8708ea888..d9fb4b043f56 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -649,6 +649,7 @@ 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);