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path: root/drivers/tty/tty_io.c
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Diffstat (limited to 'drivers/tty/tty_io.c')
-rw-r--r--drivers/tty/tty_io.c18
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);