Input: keyboard - add locking around event handling

Keyboard input handler is multiplexing events form all keyboard-like
devices in the system. Because of that per-device lock provided by
input core is not enough to prevent clashes in ked_event() and we
need our own lock to ensure that only one thread at a time executing
kbd_event().

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/char/keyboard.c b/drivers/char/keyboard.c
index 747683f055ed..ca090e57e161 100644
--- a/drivers/char/keyboard.c
+++ b/drivers/char/keyboard.c
@@ -132,6 +132,7 @@ int shift_state = 0;
  */
 
 static struct input_handler kbd_handler;
+static DEFINE_SPINLOCK(kbd_event_lock);
 static unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];  /* keyboard key bitmap */
 static unsigned char shift_down[NR_SHIFT];              /* shift state counters.. */
 static int dead_key_next;
@@ -1296,10 +1297,16 @@ static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
 static void kbd_event(struct input_handle *handle, unsigned int event_type,
                       unsigned int event_code, int value)
 {
+        /* We are called with interrupts disabled, just take the lock */
+        spin_lock(&kbd_event_lock);
+
         if (event_type == EV_MSC && event_code == MSC_RAW && HW_RAW(handle->dev))
                 kbd_rawcode(value);
         if (event_type == EV_KEY)
                 kbd_keycode(event_code, value, HW_RAW(handle->dev));
+
+        spin_unlock(&kbd_event_lock);
+
         tasklet_schedule(&keyboard_tasklet);
         do_poke_blanked_console = 1;
         schedule_console_callback();