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>

diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c
index 94f9e3a..1094265 100644 (file)
--- a/drivers/tty/hvc/hvc_console.c
+++ b/drivers/tty/hvc/hvc_console.c
@@ -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);