show_cons_active() uses the console_lock to gather information
on registered consoles. It requires that no consoles are unregistered
until it is finished. The console_list_lock should be used because
list synchronization responsibility will be removed from the
console_lock in a later change.
Note, the console_lock is still needed to serialize the device()
callback with other console operations.
Signed-off-by: John Ogness <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Petr Mladek <[email protected]>
---
drivers/tty/tty_io.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index ee4da2fec328..cafdff575716 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -3527,16 +3527,13 @@ static ssize_t show_cons_active(struct device *dev,
ssize_t count = 0;
/*
- * Hold the console_lock to guarantee that no consoles are
+ * 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.
- *
- * 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();
+ console_list_lock();
+
for_each_console(c) {
if (!c->device)
continue;
@@ -3548,6 +3545,13 @@ 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);
@@ -3563,6 +3567,8 @@ 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);
--
2.30.2