From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751548AbaEWJlY (ORCPT ); Fri, 23 May 2014 05:41:24 -0400 Received: from gate.crashing.org ([63.228.1.57]:52808 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751350AbaEWJlW (ORCPT ); Fri, 23 May 2014 05:41:22 -0400 Message-ID: <1400838066.29150.69.camel@pasglop> Subject: [PATCH] tty/hvc/hvc_console: Fix wakeup of HVC thread on hvc_kick() From: Benjamin Herrenschmidt To: Greg Kroah-Hartman Cc: Jiri Slaby , Linux Kernel list , linuxppc-dev list Date: Fri, 23 May 2014 19:41:06 +1000 Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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);