Input: libps2 - additional locking for i8042 ports

The serio ports on i8042 are not completely isolated; while we provide
enough locking to ensure proper serialization when accessing control
and data registers AUX and KBD ports can still have an effect on each
other on PS/2 protocol level. The most prominent effect is that
issuing a command for the device connected to one port may cause
abort of the command currently executing by the device connected to
another port.

Since i8042 nor serio subsystem are not aware of the details of the
PS/2 protocol (length of the commands and their replies and so on) the
locking should be done on libps2 level by adding special handling when
we see that we are dealing with serio port on i8042.

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

1 files changed, 24 insertions, 4 deletions

diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c
index 3a95b508bf2..769ba65a585 100644
--- a/drivers/input/serio/libps2.c
+++ b/drivers/input/serio/libps2.c
@@ -17,6 +17,7 @@
 #include <linux/interrupt.h>
 #include <linux/input.h>
 #include <linux/serio.h>
+#include <linux/i8042.h>
 #include <linux/init.h>
 #include <linux/libps2.h>
 
@@ -54,6 +55,24 @@ int ps2_sendbyte(struct ps2dev *ps2dev, unsigned char byte, int timeout)
 }
 EXPORT_SYMBOL(ps2_sendbyte);
 
+void ps2_begin_command(struct ps2dev *ps2dev)
+{
+	mutex_lock(&ps2dev->cmd_mutex);
+
+	if (i8042_check_port_owner(ps2dev->serio))
+		i8042_lock_chip();
+}
+EXPORT_SYMBOL(ps2_begin_command);
+
+void ps2_end_command(struct ps2dev *ps2dev)
+{
+	if (i8042_check_port_owner(ps2dev->serio))
+		i8042_unlock_chip();
+
+	mutex_unlock(&ps2dev->cmd_mutex);
+}
+EXPORT_SYMBOL(ps2_end_command);
+
 /*
  * ps2_drain() waits for device to transmit requested number of bytes
  * and discards them.
@@ -66,7 +85,7 @@ void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout)
 		maxbytes = sizeof(ps2dev->cmdbuf);
 	}
 
-	mutex_lock(&ps2dev->cmd_mutex);
+	ps2_begin_command(ps2dev);
 
 	serio_pause_rx(ps2dev->serio);
 	ps2dev->flags = PS2_FLAG_CMD;
@@ -76,7 +95,8 @@ void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout)
 	wait_event_timeout(ps2dev->wait,
 			   !(ps2dev->flags & PS2_FLAG_CMD),
 			   msecs_to_jiffies(timeout));
-	mutex_unlock(&ps2dev->cmd_mutex);
+
+	ps2_end_command(ps2dev);
 }
 EXPORT_SYMBOL(ps2_drain);
 
@@ -237,9 +257,9 @@ int ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
 {
 	int rc;
 
-	mutex_lock(&ps2dev->cmd_mutex);
+	ps2_begin_command(ps2dev);
 	rc = __ps2_command(ps2dev, param, command);
-	mutex_unlock(&ps2dev->cmd_mutex);
+	ps2_end_command(ps2dev);
 
 	return rc;
 }