[PATCH] USB: g_serial: fix deadlock with PREEMPT_RT enabled

[Michael Thalmeier]

In commit 44a0c0190b500ee6bcfc0976fe540f65dee2cd67 unlocking of spin_locks has
been removed. This patch party restores this functionality.

Signed-off-by: Michael Thalmeier <michael.thalmeier@xxxxxxx>
---
 drivers/usb/gadget/u_serial.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/drivers/usb/gadget/u_serial.c b/drivers/usb/gadget/u_serial.c
index 40f7716..a925b9e 100644
--- a/drivers/usb/gadget/u_serial.c
+++ b/drivers/usb/gadget/u_serial.c
@@ -553,7 +553,16 @@ recycle:
 	 * a workqueue, so we won't get callbacks and can hold port_lock
 	 */
 	if (tty && do_push) {
+		/*
+		 * Drop the lock here since it might end up calling
+		 * gs_flush_chars, which takes the lock.
+		 */
+		spin_unlock_irq(&port->port_lock);
 		tty_flip_buffer_push(tty);
+		spin_lock_irq(&port->port_lock);
+
+		/* tty may have been closed */
+		tty = port->port_tty;
 	}
 
 
-- 
1.7.6.4



--
Scanned by MailScanner.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/