Input: i8042 - fix locking in interrupt routine

We need to protect not only i8042 status and data register from concurrent
access from IRQ 1 and 12 but the rest of the shared state as well, so let's
move release of i8042_lock in i8042_interrupt() a little bit further down.

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

1 files changed, 26 insertions, 8 deletions

diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index 1df02d25aca5..634da68f7f35 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -369,6 +369,25 @@ static void i8042_stop(struct serio *serio)
 }
 
 /*
+ * i8042_filter() filters out unwanted bytes from the input data stream.
+ * It is called from i8042_interrupt and thus is running with interrupts
+ * off and i8042_lock held.
+ */
+static bool i8042_filter(unsigned char data, unsigned char str)
+{
+        if (unlikely(i8042_suppress_kbd_ack)) {
+                if ((~str & I8042_STR_AUXDATA) &&
+                    (data == 0xfa || data == 0xfe)) {
+                        i8042_suppress_kbd_ack--;
+                        dbg("Extra keyboard ACK - filtered out\n");
+                        return true;
+                }
+        }
+
+        return false;
+}
+
+/*
  * i8042_interrupt() is the most important function in this driver -
  * it handles the interrupts from the i8042, and sends incoming bytes
  * to the upper layers.
@@ -381,9 +400,11 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id)
         unsigned char str, data;
         unsigned int dfl;
         unsigned int port_no;
+        bool filtered;
         int ret = 1;
 
         spin_lock_irqsave(&i8042_lock, flags);
+
         str = i8042_read_status();
         if (unlikely(~str & I8042_STR_OBF)) {
                 spin_unlock_irqrestore(&i8042_lock, flags);
@@ -391,8 +412,8 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id)
                 ret = 0;
                 goto out;
         }
+
         data = i8042_read_data();
-        spin_unlock_irqrestore(&i8042_lock, flags);
 
         if (i8042_mux_present && (str & I8042_STR_AUXDATA)) {
                 static unsigned long last_transmit;
@@ -447,14 +468,11 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id)
             dfl & SERIO_PARITY ? ", bad parity" : "",
             dfl & SERIO_TIMEOUT ? ", timeout" : "");
 
-        if (unlikely(i8042_suppress_kbd_ack))
-                if (port_no == I8042_KBD_PORT_NO &&
-                    (data == 0xfa || data == 0xfe)) {
-                        i8042_suppress_kbd_ack--;
-                        goto out;
-                }
+        filtered = i8042_filter(data, str);
+
+        spin_unlock_irqrestore(&i8042_lock, flags);
 
-        if (likely(port->exists))
+        if (likely(port->exists && !filtered))
                 serio_interrupt(port->serio, data, dfl);
 
  out: