diff options
Diffstat (limited to 'drivers/tty/tty_io.c')
| -rw-r--r-- | drivers/tty/tty_io.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 24ebcb495145..034fa9865a0f 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -3530,7 +3530,14 @@ static ssize_t show_cons_active(struct device *dev, struct console *c; ssize_t count = 0; - console_lock(); + /* + * Hold the console_list_lock to guarantee that no consoles are + * unregistered until all console processing is complete. + * This also allows safe traversal of the console list and + * race-free reading of @flags. + */ + console_list_lock(); + for_each_console(c) { if (!c->device) continue; @@ -3542,6 +3549,13 @@ static ssize_t show_cons_active(struct device *dev, if (i >= ARRAY_SIZE(cs)) break; } + + /* + * Take console_lock to serialize device() callback with + * other console operations. For example, fg_console is + * modified under console_lock when switching vt. + */ + console_lock(); while (i--) { int index = cs[i]->index; struct tty_driver *drv = cs[i]->device(cs[i], &index); @@ -3557,6 +3571,8 @@ static ssize_t show_cons_active(struct device *dev, } console_unlock(); + console_list_unlock(); + return count; } static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL); |