Use srcu console list iteration for console list traversal.
Document why the console_lock is still necessary. Note that this
is a preparatory change for when console_lock no longer provides
synchronization for the console list.
Signed-off-by: John Ogness <[email protected]>
Reviewed-by: Petr Mladek <[email protected]>
---
kernel/printk/printk.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 75951c4bda05..b4be3b08d909 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2999,10 +2999,14 @@ EXPORT_SYMBOL(console_conditional_schedule);
void console_unblank(void)
{
struct console *c;
+ int cookie;
/*
- * console_unblank can no longer be called in interrupt context unless
- * oops_in_progress is set to 1..
+ * Stop console printing because the unblank() callback may
+ * assume the console is not within its write() callback.
+ *
+ * If @oops_in_progress is set, this may be an atomic context.
+ * In that case, attempt a trylock as best-effort.
*/
if (oops_in_progress) {
if (down_trylock_console_sem() != 0)
@@ -3012,9 +3016,14 @@ void console_unblank(void)
console_locked = 1;
console_may_schedule = 0;
- for_each_console(c)
- if ((c->flags & CON_ENABLED) && c->unblank)
+
+ cookie = console_srcu_read_lock();
+ for_each_console_srcu(c) {
+ if ((console_srcu_read_flags(c) & CON_ENABLED) && c->unblank)
c->unblank();
+ }
+ console_srcu_read_unlock(cookie);
+
console_unlock();
if (!oops_in_progress)
--
2.30.2