From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1767607AbXCJAGd (ORCPT ); Fri, 9 Mar 2007 19:06:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1767659AbXCJAGd (ORCPT ); Fri, 9 Mar 2007 19:06:33 -0500 Received: from yvrmail01.intrinsyc.com ([209.139.192.246]:18835 "EHLO yvrmail01.intrinsyc.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1767607AbXCJAGc (ORCPT ); Fri, 9 Mar 2007 19:06:32 -0500 Subject: Re: [PATCH] Software Suspend: Fix suspend when console is in VT_AUTO/KD_GRAPHICS mode From: Andrew Johnson To: Pavel Machek Cc: Matthew Garrett , linux-kernel@vger.kernel.org In-Reply-To: <20070309211910.GD6374@ucw.cz> References: <1173394485.28589.17.camel@localhost.localdomain> <20070309090805.GA5822@atrey.karlin.mff.cuni.cz> <20070309153456.GA28664@srcf.ucam.org> <1173466942.29923.6.camel@localhost.localdomain> <20070309211910.GD6374@ucw.cz> Content-Type: text/plain Date: Fri, 09 Mar 2007 16:05:42 -0800 Message-Id: <1173485142.30345.18.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.8.1 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 10 Mar 2007 00:06:45.0671 (UTC) FILETIME=[FD937B70:01C762A7] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2007-09-03 at 13:19 -0800, Pavel Machek wrote: > Hi! > > > > > -void set_console(int nr) > > +extern char vt_dont_switch; > > + > > What does this variable do and why do we want to use it here? > It's needed in set_console(). Console switch will fail if this is true. > 'if (' > > > + (vc->vt_mode.mode != VT_PROCESS && vc->vc_mode == > KD_GRAPHICS)) { > > + > > + return -EINVAL; > > + } > > + > > I assume you want ...mode == VT_AUTO here? > > And big comment explaining why we want this behaviour? > > And another big comment explaining why this will not break existing > set_console() users? > See updated comment in attached patch. > > - set_console(SUSPEND_CONSOLE); > > + if (set_console(SUSPEND_CONSOLE)) { > > + /* Unable to change to the new console */ > > That's not what the comment should say. > > It should explain why it is okay to proceed when we can't change to > text console. > See updated comment in attached patch. It's really up to the caller to decide what to do if we can't switch the console - currently all callers ignore the return code so I assume that it's okay to proceed anyway. -- Andrew Signed-off-by: Andrew Johnson --- diff -rup linux-2.6.20.1/drivers/char/vt.c linux/drivers/char/vt.c --- linux-2.6.20.1/drivers/char/vt.c 2007-02-19 22:34:32.000000000 -0800 +++ linux/drivers/char/vt.c 2007-03-09 15:48:29.000000000 -0800 @@ -2188,10 +2188,30 @@ static void console_callback(struct work release_console_sem(); } -void set_console(int nr) +extern char vt_dont_switch; + +int set_console(int nr) { + struct vc_data *vc = vc_cons[fg_console].d; + + if(!vc_cons_allocated(nr) || vt_dont_switch || + (vc->vt_mode.mode == VT_AUTO && vc->vc_mode == KD_GRAPHICS)) { + + /* + * Console switch will fail in console_callback() or + * change_console() so there is no point scheduling + * the callback + * + * Existing set_console() users don't check the return + * value so this shouldn't break anything + */ + return -EINVAL; + } + want_console = nr; schedule_console_callback(); + + return 0; } struct tty_driver *console_driver; diff -rup linux-2.6.20.1/drivers/char/vt_ioctl.c linux/drivers/char/vt_ioctl.c --- linux-2.6.20.1/drivers/char/vt_ioctl.c 2007-02-19 22:34:32.000000000 -0800 +++ linux/drivers/char/vt_ioctl.c 2007-03-08 14:15:41.000000000 -0800 @@ -34,7 +34,7 @@ #include #include -static char vt_dont_switch; +char vt_dont_switch; extern struct tty_driver *console_driver; #define VT_IS_IN_USE(i) (console_driver->ttys[i] && console_driver->ttys[i]->count) diff -rup linux-2.6.20.1/include/linux/kbd_kern.h linux/include/linux/kbd_kern.h --- linux-2.6.20.1/include/linux/kbd_kern.h 2007-02-19 22:34:32.000000000 -0800 +++ linux/include/linux/kbd_kern.h 2007-03-08 14:15:41.000000000 -0800 @@ -75,7 +75,7 @@ extern int do_poke_blanked_console; extern void (*kbd_ledfunc)(unsigned int led); -extern void set_console(int nr); +extern int set_console(int nr); extern void schedule_console_callback(void); static inline void set_leds(void) diff -rup linux-2.6.20.1/kernel/power/console.c linux/kernel/power/console.c --- linux-2.6.20.1/kernel/power/console.c 2007-02-19 22:34:32.000000000 -0800 +++ linux/kernel/power/console.c 2007-03-09 15:52:32.000000000 -0800 @@ -27,7 +27,15 @@ int pm_prepare_console(void) return 1; } - set_console(SUSPEND_CONSOLE); + if (set_console(SUSPEND_CONSOLE)) { + /* + * We're unable to switch to the SUSPEND_CONSOLE. + * Let the calling function know so it can decide + * what to do. + */ + release_console_sem(); + return 1; + } release_console_sem(); if (vt_waitactive(SUSPEND_CONSOLE)) {