From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 59FEB1A0590 for ; Wed, 28 May 2014 10:01:40 +1000 (EST) Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id A92F31400DA for ; Wed, 28 May 2014 10:01:39 +1000 (EST) Message-ID: <1401235290.8262.9.camel@pasglop> Subject: Re: [PATCH] tty/hvc/hvc_console: Fix wakeup of HVC thread on hvc_kick() From: Benjamin Herrenschmidt To: Greg Kroah-Hartman Date: Wed, 28 May 2014 10:01:30 +1000 In-Reply-To: <1400838066.29150.69.camel@pasglop> References: <1400838066.29150.69.camel@pasglop> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: linuxppc-dev list , Jiri Slaby , Linux Kernel list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 > --- > 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); >