diff options
| -rw-r--r-- | drivers/tty/vt/vt.c | 61 |
1 files changed, 51 insertions, 10 deletions
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index b075489..08e303c 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -108,6 +108,7 @@ #define CON_DRIVER_FLAG_MODULE 1 #define CON_DRIVER_FLAG_INIT 2 #define CON_DRIVER_FLAG_ATTR 4 +#define CON_DRIVER_FLAG_ZOMBIE 8 struct con_driver { const struct consw *con; @@ -154,6 +155,7 @@ static int set_vesa_blanking(char __user *p); static void set_cursor(struct vc_data *vc); static void hide_cursor(struct vc_data *vc); static void console_callback(struct work_struct *ignored); +static void con_driver_unregister_callback(struct work_struct *ignored); static void blank_screen_t(unsigned long dummy); static void set_palette(struct vc_data *vc); @@ -183,6 +185,7 @@ static int blankinterval = 10*60; core_param(consoleblank, blankinterval, int, 0444); static DECLARE_WORK(console_work, console_callback); +static DECLARE_WORK(con_driver_unregister_work, con_driver_unregister_callback); /* * fg_console is the current virtual console, @@ -3605,7 +3608,8 @@ static int do_register_con_driver(const struct consw *csw, int first, int last) for (i = 0; i < MAX_NR_CON_DRIVER; i++) { con_driver = ®istered_con_driver[i]; - if (con_driver->con == NULL) { + if (con_driver->con == NULL && + !(con_driver->flag & CON_DRIVER_FLAG_ZOMBIE)) { con_driver->con = csw; con_driver->desc = desc; con_driver->node = i; @@ -3667,16 +3671,20 @@ int do_unregister_con_driver(const struct consw *csw) struct con_driver *con_driver = ®istered_con_driver[i]; if (con_driver->con == csw) { - vtconsole_deinit_device(con_driver); - device_destroy(vtconsole_class, - MKDEV(0, con_driver->node)); + /* + * Defer the removal of the sysfs entries since that + * will acquire the kernfs s_active lock and we can't + * acquire this lock while holding the console lock: + * the unbind sysfs entry imposes already the opposite + * order. Reset con already here to prevent any later + * lookup to succeed and mark this slot as zombie, so + * it won't get reused until we complete the removal + * in the deferred work. + */ con_driver->con = NULL; - con_driver->desc = NULL; - con_driver->dev = NULL; - con_driver->node = 0; - con_driver->flag = 0; - con_driver->first = 0; - con_driver->last = 0; + con_driver->flag = CON_DRIVER_FLAG_ZOMBIE; + schedule_work(&con_driver_unregister_work); + return 0; } } @@ -3685,6 +3693,39 @@ int do_unregister_con_driver(const struct consw *csw) } EXPORT_SYMBOL_GPL(do_unregister_con_driver); +static void con_driver_unregister_callback(struct work_struct *ignored) +{ + int i; + + console_lock(); + + for (i = 0; i < MAX_NR_CON_DRIVER; i++) { + struct con_driver *con_driver = ®istered_con_driver[i]; + + if (!(con_driver->flag & CON_DRIVER_FLAG_ZOMBIE)) + continue; + + console_unlock(); + + vtconsole_deinit_device(con_driver); + device_destroy(vtconsole_class, MKDEV(0, con_driver->node)); + + console_lock(); + + if (WARN_ON_ONCE(con_driver->con)) + con_driver->con = NULL; + con_driver->desc = NULL; + con_driver->dev = NULL; + con_driver->node = 0; + WARN_ON_ONCE(con_driver->flag != CON_DRIVER_FLAG_ZOMBIE); + con_driver->flag = 0; + con_driver->first = 0; + con_driver->last = 0; + } + + console_unlock(); +} + /* * If we support more console drivers, this function is used * when a driver wants to take over some existing consoles |