1 From a325a46edc23a9c267ac060299f3ba9955c1ca57 Mon Sep 17 00:00:00 2001
2 From: Jon Povey <jon.povey@racelogic.co.uk>
3 Date: Mon, 14 Jun 2010 19:41:04 +0900
4 Subject: [PATCH] USB: g_serial: don't set low_latency flag
6 No longer set low_latency flag as it causes this warning backtrace:
8 WARNING: at kernel/mutex.c:207 __mutex_lock_slowpath+0x6c/0x288()
10 Fix associated locking and wakeups.
12 Signed-off-by: Jon Povey <jon.povey@racelogic.co.uk>
13 Cc: Maulik Mankad <x0082077@ti.com>
14 Cc: stable <stable@kernel.org>
15 Acked-by: David Brownell <dbrownell@users.sourceforge.net>
16 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
18 drivers/usb/gadget/u_serial.c | 15 ++-------------
19 1 files changed, 2 insertions(+), 13 deletions(-)
21 diff --git a/drivers/usb/gadget/u_serial.c b/drivers/usb/gadget/u_serial.c
22 index 5c83a87..b09c4b2 100644
23 --- a/drivers/usb/gadget/u_serial.c
24 +++ b/drivers/usb/gadget/u_serial.c
25 @@ -550,17 +550,11 @@ recycle:
26 list_move(&req->list, &port->read_pool);
29 - /* Push from tty to ldisc; this is immediate with low_latency, and
30 - * may trigger callbacks to this driver ... so drop the spinlock.
31 + /* Push from tty to ldisc; without low_latency set this is handled by
32 + * a workqueue, so we won't get callbacks and can hold port_lock
35 - spin_unlock_irq(&port->port_lock);
36 tty_flip_buffer_push(tty);
37 - wake_up_interruptible(&tty->read_wait);
38 - spin_lock_irq(&port->port_lock);
40 - /* tty may have been closed */
41 - tty = port->port_tty;
45 @@ -798,11 +792,6 @@ static int gs_open(struct tty_struct *tty, struct file *file)
47 port->openclose = false;
49 - /* low_latency means ldiscs work in tasklet context, without
50 - * needing a workqueue schedule ... easier to keep up.
52 - tty->low_latency = 1;
54 /* if connected, start the I/O stream */
56 struct gserial *gser = port->port_usb;