Commit 15a27431 authored May 23, 2014 by Benjamin Herrenschmidt Committed by Greg Kroah-Hartman May 28, 2014

tty/hvc/hvc_console: Fix wakeup of HVC thread on hvc_kick()



Some backends call hvc_kick() to wakeup the HVC thread from its
slumber upon incoming characters. This however doesn't work
properly because it uses msleep_interruptible() which is mostly
immune to wake_up_process(). It will basically go back to sleep
until the timeout is expired (only signals can really wake it).

Replace it with a simple shedule_timeout_interruptible() instead,
which may wakeup earlier every now and then but we really don't
care in this case.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 8e25f8ce

drivers/tty/hvc/hvc_console.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -760,10 +760,17 @@ static int khvcd(void *unused)
		if (poll_mask == 0)
		schedule();
		else {
		unsigned long j_timeout;

		if (timeout < MAX_TIMEOUT)
		timeout += (timeout >> 6) + 1;

		msleep_interruptible(timeout);
		/*
		* We don't use msleep_interruptible otherwise
		* "kick" will fail to wake us up
		*/
		j_timeout = msecs_to_jiffies(timeout) + 1;
		schedule_timeout_interruptible(j_timeout);
		}
		}
		__set_current_state(TASK_RUNNING);