When the global console loglevel is changed via sysrq, clear any
per-console loglevels that may have been set. This ensures that the
sysrq loglevel change takes effect immediately across all consoles.
Warn once if any per-console loglevels were being overridden.
Signed-off-by: Chris Down <chris@chrisdown.name>
---
drivers/tty/sysrq.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index 97f8a9a52285..1763eaefd581 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -51,6 +51,7 @@
#include <linux/syscalls.h>
#include <linux/of.h>
#include <linux/rcupdate.h>
+#include <linux/console.h>
#include <asm/ptrace.h>
#include <asm/irq_regs.h>
@@ -101,10 +102,25 @@ __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
static void sysrq_handle_loglevel(u8 key)
{
u8 loglevel = key - '0';
+ int cookie;
+ struct console *con;
console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
pr_info("Loglevel set to %u\n", loglevel);
console_loglevel = loglevel;
+
+ /*
+ * When changing loglevel via sysrq, override all per-console loglevels
+ * to ensure the new global loglevel takes effect immediately and all
+ * consoles see the messages.
+ */
+ cookie = console_srcu_read_lock();
+ for_each_console_srcu(con) {
+ if (has_per_console_loglevel(con))
+ pr_warn_once("Overriding per-console loglevel from sysrq\n");
+ WRITE_ONCE(con->level, LOGLEVEL_DEFAULT);
+ }
+ console_srcu_read_unlock(cookie);
}
static const struct sysrq_key_op sysrq_loglevel_op = {
.handler = sysrq_handle_loglevel,
--
2.51.2