target/linux/generic/pending-4.9/890-uart_optional_sysrq.patch

   1 From: John Crispin <john@phrozen.org>
   2 Subject: serial: do not accept sysrq characters via serial port
   3
   4 many embedded boards have a disconnected TTL level serial which can
   5 generate some garbage that can lead to spurious false sysrq detects.
   6
   7 [john@phrozen.org: sent upstream 22.12.2016]
   8
   9 Signed-off-by: John Crispin <john@phrozen.org>
  10 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  11 ---
  12  include/linux/serial_core.h | 2 +-
  13  lib/Kconfig.debug           | 5 +++++
  14  2 files changed, 6 insertions(+), 1 deletion(-)
  15
  16 diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
  17 index 344201437017..7e6165bc1cef 100644
  18 --- a/include/linux/serial_core.h
  19 +++ b/include/linux/serial_core.h
  20 @@ -448,7 +448,7 @@ extern void uart_handle_cts_change(struct uart_port *uport,
  21  extern void uart_insert_char(struct uart_port *port, unsigned int status,
  22                  unsigned int overrun, unsigned int ch, unsigned int flag);
  23
  24 -#ifdef SUPPORT_SYSRQ
  25 +#if defined(SUPPORT_SYSRQ) && defined(CONFIG_MAGIC_SYSRQ_SERIAL)
  26  static inline int
  27  uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
  28  {
  29 diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
  30 index a6c8db1d62f6..062c580cdd68 100644
  31 --- a/lib/Kconfig.debug
  32 +++ b/lib/Kconfig.debug
  33 @@ -397,6 +397,11 @@ config MAGIC_SYSRQ_DEFAULT_ENABLE
  34           This may be set to 1 or 0 to enable or disable them all, or
  35           to a bitmask as described in Documentation/sysrq.txt.
  36
  37 +config MAGIC_SYSRQ_SERIAL
  38 +       bool "Enable magic SysRq key over serial"
  39 +       depends on MAGIC_SYSRQ
  40 +       default y
  41 +
  42  config DEBUG_KERNEL
  43         bool "Kernel debugging"
  44         help
  45 --
  46 2.11.0
  47