From 5592fb92225d302b3e3039ed762bb1e1c55f9eea Mon Sep 17 00:00:00 2001 From: Jon Povey Date: Mon, 14 Jun 2010 19:41:04 +0900 Subject: [PATCH] USB: g_serial: don't set low_latency flag commit 44a0c0190b500ee6bcfc0976fe540f65dee2cd67 upstream. No longer set low_latency flag as it causes this warning backtrace: WARNING: at kernel/mutex.c:207 __mutex_lock_slowpath+0x6c/0x288() Fix associated locking and wakeups. Signed-off-by: Jon Povey Cc: Maulik Mankad Acked-by: David Brownell Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/u_serial.c | 15 ++------------- 1 file changed, 2 insertions(+), 13 deletions(-) diff --git a/drivers/usb/gadget/u_serial.c b/drivers/usb/gadget/u_serial.c index adf8260c3a6a..f10311768f90 100644 --- a/drivers/usb/gadget/u_serial.c +++ b/drivers/usb/gadget/u_serial.c @@ -535,17 +535,11 @@ recycle: list_move(&req->list, &port->read_pool); } - /* Push from tty to ldisc; this is immediate with low_latency, and - * may trigger callbacks to this driver ... so drop the spinlock. + /* Push from tty to ldisc; without low_latency set this is handled by + * a workqueue, so we won't get callbacks and can hold port_lock */ if (tty && do_push) { - spin_unlock_irq(&port->port_lock); tty_flip_buffer_push(tty); - wake_up_interruptible(&tty->read_wait); - spin_lock_irq(&port->port_lock); - - /* tty may have been closed */ - tty = port->port_tty; } @@ -783,11 +777,6 @@ static int gs_open(struct tty_struct *tty, struct file *file) port->open_count = 1; port->openclose = false; - /* low_latency means ldiscs work in tasklet context, without - * needing a workqueue schedule ... easier to keep up. - */ - tty->low_latency = 1; - /* if connected, start the I/O stream */ if (port->port_usb) { struct gserial *gser = port->port_usb; -- 2.39.5