On Thu, May 22, 2014 at 04:57:31PM +0200, Jean-Jacques Hiblot wrote: > With CONFIG_PREEMPT_RT_FULL the tty_flip_buffer_push(..) actions are executed > immeditely (same behaviour as if low_latency flag was set). We thus have to > release port_lock before callng tty_flip_buffer_push(). > > This issue resultst of commits: > 44a0c019: USB: g_serial: don't set low_latency flag > dc0cbd1b: serial: 8250: Call flush_to_ldisc when the irq is threaded > > Signed-off-by: Jean-Jacques Hiblot <[email protected]> > --- > changes since v1: > - fix compilation problem: use port.tty instead of port->port_tty > > drivers/usb/gadget/u_serial.c | 23 ++++++++++++++++++----- > 1 file changed, 18 insertions(+), 5 deletions(-) > > diff --git a/drivers/usb/gadget/u_serial.c b/drivers/usb/gadget/u_serial.c > index b369292..3d4246d 100644 > --- a/drivers/usb/gadget/u_serial.c > +++ b/drivers/usb/gadget/u_serial.c > @@ -549,12 +549,25 @@ static void gs_rx_push(unsigned long _port) > port->read_started--; > } > > - /* 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 (do_push) > + /* Push from tty to ldisc */ > + if (do_push) { > +#ifndef CONFIG_PREEMPT_RT_FULL
can we drop the ifdef somehow ? Are there no better options here ? > + /* without low_latency set this is handled by a workqueue, so > + * we won't get callbacks and can hold port_lock > + */ > tty_flip_buffer_push(&port->port); > - > +#else > + /* CONFIG_PREEMPT_RT_FULL makes this a synchronous action. and > + * it may trigger synchronous callbacks to this driver. We need > + * to release the lock. > + */ > + spin_unlock_irq(&port->port_lock); > + tty_flip_buffer_push(&port->port); > + spin_lock_irq(&port->port_lock); > + /* tty may have been closed */ > + tty = port->port.tty; > +#endif > + } > > /* We want our data queue to become empty ASAP, keeping data > * in the tty and ldisc (not here). If we couldn't push any > -- > 1.9.2 > -- balbi
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