On Fri, 2014-05-23 at 19:41 +1000, Benjamin Herrenschmidt wrote:
> 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.
Nobody commented ? :-)
Greg, do you want to take this in the tty tree or can I stick it in
powerpc ?
Cheers,
Ben
> Signed-off-by: Benjamin Herrenschmidt <b...@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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