From: Jon Povey Date: Mon, 14 Jun 2010 10:41:04 +0000 (+0900) Subject: USB: g_serial: don't set low_latency flag X-Git-Tag: v2.6.35-rc4~18^2~21 X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=44a0c0190b500ee6bcfc0976fe540f65dee2cd67;p=~emulex%2Finfiniband.git USB: g_serial: don't set low_latency flag 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 Cc: stable Acked-by: David Brownell Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/gadget/u_serial.c b/drivers/usb/gadget/u_serial.c index 16bdf77f582..a0f79df4c6c 100644 --- a/drivers/usb/gadget/u_serial.c +++ b/drivers/usb/gadget/u_serial.c @@ -536,17 +536,11 @@ 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; } @@ -784,11 +778,6 @@ 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;