Commit 40974618 authored by Dmitry Torokhov's avatar Dmitry Torokhov

Input: i8042 - break load dependency between atkbd/psmouse and i8042

As explained in we
have a hard load dependency between i8042 and atkbd which prevents
keyboard from working on Gen2 Hyper-V VMs.

> hyperv_keyboard invokes serio_interrupt(), which needs a valid serio
> driver like atkbd.c.  atkbd.c depends on libps2.c because it invokes
> ps2_command().  libps2.c depends on i8042.c because it invokes
> i8042_check_port_owner().  As a result, hyperv_keyboard actually
> depends on i8042.c.
> For a Generation 2 Hyper-V VM (meaning no i8042 device emulated), if a
> Linux VM (like Arch Linux) happens to configure CONFIG_SERIO_I8042=m
> rather than =y, atkbd.ko can't load because i8042.ko can't load(due to
> no i8042 device emulated) and finally hyperv_keyboard can't work and
> the user can't input:
> (Ubuntu/RHEL/SUSE aren't affected since they use CONFIG_SERIO_I8042=y)

To break the dependency we move away from using i8042_check_port_owner()
and instead allow serio port owner specify a mutex that clients should use
to serialize PS/2 command stream.
Reported-by: default avatarMark Laws <>
Tested-by: default avatarMark Laws <>
Signed-off-by: default avatarDmitry Torokhov <>
parent 887ec0bf
......@@ -1277,6 +1277,7 @@ static int __init i8042_create_kbd_port(void)
serio->start = i8042_start;
serio->stop = i8042_stop;
serio->close = i8042_port_close;
serio->ps2_cmd_mutex = &i8042_mutex;
serio->port_data = port;
serio->dev.parent = &i8042_platform_device->dev;
strlcpy(serio->name, "i8042 KBD port", sizeof(serio->name));
......@@ -1373,21 +1374,6 @@ static void i8042_unregister_ports(void)
* Checks whether port belongs to i8042 controller.
bool i8042_check_port_owner(const struct serio *port)
int i;
for (i = 0; i < I8042_NUM_PORTS; i++)
if (i8042_ports[i].serio == port)
return true;
return false;
static void i8042_free_irqs(void)
if (i8042_aux_irq_registered)
......@@ -56,19 +56,17 @@ EXPORT_SYMBOL(ps2_sendbyte);
void ps2_begin_command(struct ps2dev *ps2dev)
struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
if (i8042_check_port_owner(ps2dev->serio))
void ps2_end_command(struct ps2dev *ps2dev)
if (i8042_check_port_owner(ps2dev->serio))
struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
......@@ -62,7 +62,6 @@ struct serio;
void i8042_lock_chip(void);
void i8042_unlock_chip(void);
int i8042_command(unsigned char *param, int command);
bool i8042_check_port_owner(const struct serio *);
int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str,
struct serio *serio));
int i8042_remove_filter(bool (*filter)(unsigned char data, unsigned char str,
......@@ -83,11 +82,6 @@ static inline int i8042_command(unsigned char *param, int command)
return -ENODEV;
static inline bool i8042_check_port_owner(const struct serio *serio)
return false;
static inline int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str,
struct serio *serio))
......@@ -31,7 +31,8 @@ struct serio {
struct serio_device_id id;
spinlock_t lock; /* protects critical sections from port's interrupt handler */
/* Protects critical sections from port's interrupt handler */
spinlock_t lock;
int (*write)(struct serio *, unsigned char);
int (*open)(struct serio *);
......@@ -40,16 +41,29 @@ struct serio {
void (*stop)(struct serio *);
struct serio *parent;
struct list_head child_node; /* Entry in parent->children list */
/* Entry in parent->children list */
struct list_head child_node;
struct list_head children;
unsigned int depth; /* level of nesting in serio hierarchy */
/* Level of nesting in serio hierarchy */
unsigned int depth;
struct serio_driver *drv; /* accessed from interrupt, must be protected by serio->lock and serio->sem */
struct mutex drv_mutex; /* protects serio->drv so attributes can pin driver */
* serio->drv is accessed from interrupt handlers; when modifying
* caller should acquire serio->drv_mutex and serio->lock.
struct serio_driver *drv;
/* Protects serio->drv so attributes can pin current driver */
struct mutex drv_mutex;
struct device dev;
struct list_head node;
* For use by PS/2 layer when several ports share hardware and
* may get indigestion when exposed to concurrent access (i8042).
struct mutex *ps2_cmd_mutex;
#define to_serio_port(d) container_of(d, struct serio, dev)
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