configure_kgdboc() uses the console_lock for console list iteration. Use
the console_list_lock instead because list synchronization responsibility
will be removed from the console_lock in a later change.
The SRCU iterator could have been used here, but a later change will
relocate the locking of the console_list_lock to also provide
synchronization against register_console().
Note, the console_lock is still needed to serialize the device()
callback with other console operations.
Signed-off-by: John Ogness <john.ogn...@linutronix.de>
---
drivers/tty/serial/kgdboc.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
index 5be381003e58..82b4b4d67823 100644
--- a/drivers/tty/serial/kgdboc.c
+++ b/drivers/tty/serial/kgdboc.c
@@ -193,7 +193,16 @@ static int configure_kgdboc(void)
if (!p)
goto noconfig;
+ /* For safe traversal of the console list. */
+ console_list_lock();
+
+ /*
+ * 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();
+
for_each_console(cons) {
int idx;
if (cons->device && cons->device(cons, &idx) == p &&
@@ -202,8 +211,11 @@ static int configure_kgdboc(void)
break;
}
}
+
console_unlock();
+ console_list_unlock();
+
kgdb_tty_driver = p;
kgdb_tty_line = tty_line;
@@ -451,6 +463,7 @@ static void kgdboc_earlycon_pre_exp_handler(void)
{
struct console *con;
static bool already_warned;
+ int cookie;
if (already_warned)
return;
@@ -463,9 +476,14 @@ static void kgdboc_earlycon_pre_exp_handler(void)
* serial drivers might be OK with this, print a warning once per
* boot if we detect this case.
*/
- for_each_console(con)
+ cookie = console_srcu_read_lock();
+ for_each_console_srcu(con) {
if (con == kgdboc_earlycon_io_ops.cons)
- return;
+ break;
+ }
+ console_srcu_read_unlock(cookie);
+ if (con)
+ return;
already_warned = true;
pr_warn("kgdboc_earlycon is still using bootconsole\n");
--
2.30.2
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