Re: [PATCH] tty/hvc/hvc_console: Fix wakeup of HVC thread on hvc_kick()
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2014-05-28 00:01:45
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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
quoted hunk ↗ jump to hunk
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);