From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751128AbdCQFJq (ORCPT ); Fri, 17 Mar 2017 01:09:46 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:42160 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750898AbdCQFJp (ORCPT ); Fri, 17 Mar 2017 01:09:45 -0400 Date: Fri, 17 Mar 2017 14:09:30 +0900 From: Greg Kroah-Hartman To: Jan Dakinevich Cc: Jiri Slaby , Peter Hurley , Dan Carpenter , Arnd Bergmann , Amit Shah , virtualization@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] tty: hvc: don't allocate a buffer for console print on stack Message-ID: <20170317050930.GB28075@kroah.com> References: <1487364165-21882-1-git-send-email-jan.dakinevich@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1487364165-21882-1-git-send-email-jan.dakinevich@gmail.com> User-Agent: Mutt/1.8.0 (2017-02-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 17, 2017 at 11:42:45PM +0300, Jan Dakinevich wrote: > The buffer is used by virtio console driver as DMA buffer. Since v4.9 > (if VMAP_STACK is enabled) we shouldn't use the stack for DMA. You shouldn't use 'static' data either, that's not always guaranteed to be DMA-able, right? > > Signed-off-by: Jan Dakinevich > --- > drivers/tty/hvc/hvc_console.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c > index 9b5c0fb..1ce6aaf 100644 > --- a/drivers/tty/hvc/hvc_console.c > +++ b/drivers/tty/hvc/hvc_console.c > @@ -143,10 +143,15 @@ static struct hvc_struct *hvc_get_by_index(int index) > static void hvc_console_print(struct console *co, const char *b, > unsigned count) > { > - char c[N_OUTBUF] __ALIGNED__; > unsigned i = 0, n = 0; > int r, donecr = 0, index = co->index; > > + /* > + * Access to the buffer is serialized by console_sem in caller code from > + * kernel/printk/printk.c > + */ > + static char c[N_OUTBUF] __ALIGNED__; What about allocating it dynamically? That's the correct thing to do. thanks, greg k-h