From: Alan Cox <alan at lxorguk.ukuu.org.uk> 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 s partly a band aid, the fb layer is terminally confused about the locking rules it uses for its notifiers it seems. Signed-off-by: Alan Cox <alan at linux.intel.com> [danvet: Tiny whitespace cleanup.] Reported-and-tested-by: Hugh Dickins <hughd at google.com> Reported-and-tested-by: Sasha Levin <levinsasha928 at gmail.com> References: https://lkml.org/lkml/2012/10/25/516 Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch> --- drivers/tty/vt/vt.c | 81 +++++++++++++++++++++++++++++++---------- drivers/video/console/fbcon.c | 30 ++++++++++++++- drivers/video/fbmem.c | 5 +-- drivers/video/fbsysfs.c | 3 ++ include/linux/console.h | 1 + 5 files changed, 97 insertions(+), 23 deletions(-) diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index 8fd8968..a38d9d1 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -2987,7 +2987,7 @@ 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; @@ -2998,7 +2998,7 @@ 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++) { @@ -3083,11 +3083,22 @@ 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) { @@ -3199,9 +3210,9 @@ 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; @@ -3492,28 +3503,18 @@ 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]; @@ -3566,10 +3567,29 @@ 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); /** @@ -3625,6 +3645,29 @@ EXPORT_SYMBOL(unregister_con_driver); * * 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; +} +/* + * 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; diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c index fdefa8f..c75f8ce 100644 --- a/drivers/video/console/fbcon.c +++ b/drivers/video/console/fbcon.c @@ -529,6 +529,34 @@ 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; @@ -3115,7 +3143,7 @@ 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 3ff0105..d8d9831 100644 --- a/drivers/video/fbmem.c +++ b/drivers/video/fbmem.c @@ -1650,7 +1650,9 @@ 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; } @@ -1853,11 +1855,8 @@ 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 dedb082..4ef4307 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); -- 1.7.10.4
