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Subject[PATCH] tty/hvc/hvc_console: Fix wakeup of HVC thread on hvc_kick()
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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>
---
drivers/tty/hvc/hvc_console.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

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



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