serial: core: Print escaped SysRq Magic sequence if enabled

It is useful to see on the serial console the magic sequence itself
to enable SysRq without rummaging source code.

Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200310174337.74109-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index f5c8cf8475329349b4001cfd688f976a547df95e..c93d4e600f9109d8e301c6d277c8eee6d16ed032 100644 (file)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -3092,8 +3092,11 @@ static const char sysrq_toggle_seq[] = CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE;
 
 static void uart_sysrq_on(struct work_struct *w)
 {
+       int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
+
        sysrq_toggle_support(1);
-       pr_info("SysRq is enabled by magic sequence on serial\n");
+       pr_info("SysRq is enabled by magic sequence '%*pE' on serial\n",
+               sysrq_toggle_seq_len, sysrq_toggle_seq);
 }
 static DECLARE_WORK(sysrq_enable_work, uart_sysrq_on);