From patchwork Thu Feb 28 11:57:58 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 223914 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id E895C2C02AC for ; Thu, 28 Feb 2013 22:58:17 +1100 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UB27h-0003bC-JI; Thu, 28 Feb 2013 11:58:05 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UB27e-0003Z1-VR for kernel-team@lists.ubuntu.com; Thu, 28 Feb 2013 11:58:02 +0000 Received: from [188.250.143.69] (helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1UB27c-0005xF-4N; Thu, 28 Feb 2013 11:58:00 +0000 From: Luis Henriques To: Alan Cox Subject: [ 3.5.y.z extended stable ] Patch "fb: rework locking to fix lock ordering on takeover" has been added to staging queue Date: Thu, 28 Feb 2013 11:57:58 +0000 Message-Id: <1362052678-19521-1-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.1.2 X-Extended-Stable: 3.5 MIME-Version: 1.0 Cc: Stephen Rothwell , Florian Tobias Schandinat , Daniel Vetter , kernel-team@lists.ubuntu.com, Jiri Kosina , Dave Airlie , Andrew Morton X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled fb: rework locking to fix lock ordering on takeover to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 88835947ba1f0a4abef11144ffa47713035f3965 Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Fri, 25 Jan 2013 10:28:15 +1000 Subject: [PATCH] fb: rework locking to fix lock ordering on takeover commit 50e244cc793d511b86adea24972f3a7264cae114 upstream. Adjust the console layer to allow a take over call where the caller already holds the locks. Make the fb layer lock in order. This is partly a band aid, the fb layer is terminally confused about the locking rules it uses for its notifiers it seems. [akpm@linux-foundation.org: remove stray non-ascii char, tidy comment] [akpm@linux-foundation.org: export do_take_over_console()] [airlied: cleanup another non-ascii char] Signed-off-by: Alan Cox Cc: Florian Tobias Schandinat Cc: Stephen Rothwell Cc: Jiri Kosina Tested-by: Sedat Dilek Reviewed-by: Daniel Vetter Signed-off-by: Andrew Morton Signed-off-by: Dave Airlie Signed-off-by: Luis Henriques --- drivers/tty/vt/vt.c | 93 ++++++++++++++++++++++++++++++++----------- drivers/video/console/fbcon.c | 29 +++++++++++++- drivers/video/fbmem.c | 5 +-- drivers/video/fbsysfs.c | 3 ++ include/linux/console.h | 1 + 5 files changed, 104 insertions(+), 27 deletions(-) -- 1.8.1.2 diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index 3b4f5b6..f7ffae5 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -3017,7 +3017,7 @@ int __init vty_init(const struct file_operations *console_fops) static struct class *vtconsole_class; -static int bind_con_driver(const struct consw *csw, int first, int last, +static int do_bind_con_driver(const struct consw *csw, int first, int last, int deflt) { struct module *owner = csw->owner; @@ -3028,7 +3028,7 @@ static int bind_con_driver(const struct consw *csw, int first, int last, if (!try_module_get(owner)) return -ENODEV; - console_lock(); + WARN_CONSOLE_UNLOCKED(); /* check if driver is registered */ for (i = 0; i < MAX_NR_CON_DRIVER; i++) { @@ -3113,11 +3113,22 @@ static int bind_con_driver(const struct consw *csw, int first, int last, retval = 0; err: - console_unlock(); module_put(owner); return retval; }; + +static int bind_con_driver(const struct consw *csw, int first, int last, + int deflt) +{ + int ret; + + console_lock(); + ret = do_bind_con_driver(csw, first, last, deflt); + console_unlock(); + return ret; +} + #ifdef CONFIG_VT_HW_CONSOLE_BINDING static int con_is_graphics(const struct consw *csw, int first, int last) { @@ -3229,9 +3240,9 @@ int unbind_con_driver(const struct consw *csw, int first, int last, int deflt) if (!con_is_bound(csw)) con_driver->flag &= ~CON_DRIVER_FLAG_INIT; - console_unlock(); /* ignore return value, binding should not fail */ - bind_con_driver(defcsw, first, last, deflt); + do_bind_con_driver(defcsw, first, last, deflt); + console_unlock(); err: module_put(owner); return retval; @@ -3522,28 +3533,18 @@ int con_debug_leave(void) } EXPORT_SYMBOL_GPL(con_debug_leave); -/** - * register_con_driver - register console driver to console layer - * @csw: console driver - * @first: the first console to take over, minimum value is 0 - * @last: the last console to take over, maximum value is MAX_NR_CONSOLES -1 - * - * DESCRIPTION: This function registers a console driver which can later - * bind to a range of consoles specified by @first and @last. It will - * also initialize the console driver by calling con_startup(). - */ -int register_con_driver(const struct consw *csw, int first, int last) +static int do_register_con_driver(const struct consw *csw, int first, int last) { struct module *owner = csw->owner; struct con_driver *con_driver; const char *desc; int i, retval = 0; + WARN_CONSOLE_UNLOCKED(); + if (!try_module_get(owner)) return -ENODEV; - console_lock(); - for (i = 0; i < MAX_NR_CON_DRIVER; i++) { con_driver = ®istered_con_driver[i]; @@ -3596,10 +3597,29 @@ int register_con_driver(const struct consw *csw, int first, int last) } err: - console_unlock(); module_put(owner); return retval; } + +/** + * register_con_driver - register console driver to console layer + * @csw: console driver + * @first: the first console to take over, minimum value is 0 + * @last: the last console to take over, maximum value is MAX_NR_CONSOLES -1 + * + * DESCRIPTION: This function registers a console driver which can later + * bind to a range of consoles specified by @first and @last. It will + * also initialize the console driver by calling con_startup(). + */ +int register_con_driver(const struct consw *csw, int first, int last) +{ + int retval; + + console_lock(); + retval = do_register_con_driver(csw, first, last); + console_unlock(); + return retval; +} EXPORT_SYMBOL(register_con_driver); /** @@ -3653,17 +3673,44 @@ EXPORT_SYMBOL(unregister_con_driver); * when a driver wants to take over some existing consoles * and become default driver for newly opened ones. * - * take_over_console is basically a register followed by unbind + * take_over_console is basically a register followed by unbind + */ +int do_take_over_console(const struct consw *csw, int first, int last, int deflt) +{ + int err; + + err = do_register_con_driver(csw, first, last); + /* + * If we get an busy error we still want to bind the console driver + * and return success, as we may have unbound the console driver + * but not unregistered it. + */ + if (err == -EBUSY) + err = 0; + if (!err) + do_bind_con_driver(csw, first, last, deflt); + + return err; +} +EXPORT_SYMBOL_GPL(do_take_over_console); + +/* + * If we support more console drivers, this function is used + * when a driver wants to take over some existing consoles + * and become default driver for newly opened ones. + * + * take_over_console is basically a register followed by unbind */ int take_over_console(const struct consw *csw, int first, int last, int deflt) { int err; err = register_con_driver(csw, first, last); - /* if we get an busy error we still want to bind the console driver + /* + * If we get an busy error we still want to bind the console driver * and return success, as we may have unbound the console driver -  * but not unregistered it. - */ + * but not unregistered it. + */ if (err == -EBUSY) err = 0; if (!err) diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c index bdcd34d..7ccec55 100644 --- a/drivers/video/console/fbcon.c +++ b/drivers/video/console/fbcon.c @@ -529,6 +529,33 @@ static int search_for_mapped_con(void) return retval; } +static int do_fbcon_takeover(int show_logo) +{ + int err, i; + + if (!num_registered_fb) + return -ENODEV; + + if (!show_logo) + logo_shown = FBCON_LOGO_DONTSHOW; + + for (i = first_fb_vc; i <= last_fb_vc; i++) + con2fb_map[i] = info_idx; + + err = do_take_over_console(&fb_con, first_fb_vc, last_fb_vc, + fbcon_is_default); + + if (err) { + for (i = first_fb_vc; i <= last_fb_vc; i++) + con2fb_map[i] = -1; + info_idx = -1; + } else { + fbcon_has_console_bind = 1; + } + + return err; +} + static int fbcon_takeover(int show_logo) { int err, i; @@ -3121,7 +3148,7 @@ static int fbcon_fb_registered(struct fb_info *info) } if (info_idx != -1) - ret = fbcon_takeover(1); + ret = do_fbcon_takeover(1); } else { for (i = first_fb_vc; i <= last_fb_vc; i++) { if (con2fb_map_boot[i] == idx) diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c index 0dff12a..616278a 100644 --- a/drivers/video/fbmem.c +++ b/drivers/video/fbmem.c @@ -1651,7 +1651,9 @@ static int do_register_framebuffer(struct fb_info *fb_info) event.info = fb_info; if (!lock_fb_info(fb_info)) return -ENODEV; + console_lock(); fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event); + console_unlock(); unlock_fb_info(fb_info); return 0; } @@ -1854,11 +1856,8 @@ int fb_new_modelist(struct fb_info *info) err = 1; if (!list_empty(&info->modelist)) { - if (!lock_fb_info(info)) - return -ENODEV; event.info = info; err = fb_notifier_call_chain(FB_EVENT_NEW_MODELIST, &event); - unlock_fb_info(info); } return err; diff --git a/drivers/video/fbsysfs.c b/drivers/video/fbsysfs.c index a55e366..ef476b0 100644 --- a/drivers/video/fbsysfs.c +++ b/drivers/video/fbsysfs.c @@ -177,6 +177,8 @@ static ssize_t store_modes(struct device *device, if (i * sizeof(struct fb_videomode) != count) return -EINVAL; + if (!lock_fb_info(fb_info)) + return -ENODEV; console_lock(); list_splice(&fb_info->modelist, &old_list); fb_videomode_to_modelist((const struct fb_videomode *)buf, i, @@ -188,6 +190,7 @@ static ssize_t store_modes(struct device *device, fb_destroy_modelist(&old_list); console_unlock(); + unlock_fb_info(fb_info); return 0; } diff --git a/include/linux/console.h b/include/linux/console.h index 7201ce4..e8ea7d7 100644 --- a/include/linux/console.h +++ b/include/linux/console.h @@ -78,6 +78,7 @@ int con_is_bound(const struct consw *csw); int register_con_driver(const struct consw *csw, int first, int last); int unregister_con_driver(const struct consw *csw); int take_over_console(const struct consw *sw, int first, int last, int deflt); +int do_take_over_console(const struct consw *sw, int first, int last, int deflt); void give_up_console(const struct consw *sw); #ifdef CONFIG_HW_CONSOLE int con_debug_enter(struct vc_data *vc);