[PATCH 1/2] Input: i8042 - Prevent intermixing i8042 commands

From: Raul E Rangel
Date: Thu Aug 27 2020 - 15:52:50 EST

The i8042_mutex must be held by writers of the AUX and KBD ports, as
well as users of i8042_command. There were a lot of users of
i8042_command that were not calling i8042_lock_chip/i8042_unlock_chip.
This resulted in i8042_commands being issues in between PS/2
transactions.

This change moves the mutex lock into i8042_command and removes the
burden of locking the mutex from the callers.

It is expected that the i8042_mutex is locked before calling
i8042_aux_write or i8042_kbd_write. This is currently done by the PS/2
layer via ps2_begin_command and ps2_end_command. Other modules
(serio_raw) do not currently lock the mutex, so there is still a
possibility for intermixed commands.

Signed-off-by: Raul E Rangel <rrangel@xxxxxxxxxxxx>
---

drivers/input/serio/i8042.c | 29 ++++++++++++++---------------
drivers/leds/leds-clevo-mail.c | 9 ---------
drivers/platform/x86/acer-wmi.c | 2 --
drivers/platform/x86/amilo-rfkill.c | 2 --
include/linux/i8042.h | 10 ----------
5 files changed, 14 insertions(+), 38 deletions(-)

diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index 0dddf273afd94..8590e51bcc087 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -137,8 +137,7 @@ static DEFINE_SPINLOCK(i8042_lock);

/*
* Writers to AUX and KBD ports as well as users issuing i8042_command
- * directly should acquire i8042_mutex (by means of calling
- * i8042_lock_chip() and i8042_unlock_ship() helpers) to ensure that
+ * directly should acquire i8042_mutex to ensure that
* they do not disturb each other (unfortunately in many i8042
* implementations write to one of the ports will immediately abort
* command that is being processed by another port).
@@ -173,18 +172,6 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id);
static bool (*i8042_platform_filter)(unsigned char data, unsigned char str,
struct serio *serio);

-void i8042_lock_chip(void)
-{
- mutex_lock(&i8042_mutex);
-}
-EXPORT_SYMBOL(i8042_lock_chip);
-
-void i8042_unlock_chip(void)
-{
- mutex_unlock(&i8042_mutex);
-}
-EXPORT_SYMBOL(i8042_unlock_chip);
-
int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str,
struct serio *serio))
{
@@ -343,10 +330,14 @@ int i8042_command(unsigned char *param, int command)
unsigned long flags;
int retval;

+ mutex_lock(&i8042_mutex);
+
spin_lock_irqsave(&i8042_lock, flags);
retval = __i8042_command(param, command);
spin_unlock_irqrestore(&i8042_lock, flags);

+ mutex_unlock(&i8042_mutex);
+
return retval;
}
EXPORT_SYMBOL(i8042_command);
@@ -379,10 +370,18 @@ static int i8042_kbd_write(struct serio *port, unsigned char c)
static int i8042_aux_write(struct serio *serio, unsigned char c)
{
struct i8042_port *port = serio->port_data;
+ unsigned long flags;
+ int retval = 0;
+
+ spin_lock_irqsave(&i8042_lock, flags);

- return i8042_command(&c, port->mux == -1 ?
+ retval = __i8042_command(&c, port->mux == -1 ?
I8042_CMD_AUX_SEND :
I8042_CMD_MUX_SEND + port->mux);
+
+ spin_unlock_irqrestore(&i8042_lock, flags);
+
+ return retval;
}


diff --git a/drivers/leds/leds-clevo-mail.c b/drivers/leds/leds-clevo-mail.c
index f512e99b976b1..6c3d7e54f95cf 100644
--- a/drivers/leds/leds-clevo-mail.c
+++ b/drivers/leds/leds-clevo-mail.c
@@ -95,17 +95,12 @@ MODULE_DEVICE_TABLE(dmi, clevo_mail_led_dmi_table);
static void clevo_mail_led_set(struct led_classdev *led_cdev,
enum led_brightness value)
{
- i8042_lock_chip();
-
if (value == LED_OFF)
i8042_command(NULL, CLEVO_MAIL_LED_OFF);
else if (value <= LED_HALF)
i8042_command(NULL, CLEVO_MAIL_LED_BLINK_0_5HZ);
else
i8042_command(NULL, CLEVO_MAIL_LED_BLINK_1HZ);
-
- i8042_unlock_chip();
-
}

static int clevo_mail_led_blink(struct led_classdev *led_cdev,
@@ -114,8 +109,6 @@ static int clevo_mail_led_blink(struct led_classdev *led_cdev,
{
int status = -EINVAL;

- i8042_lock_chip();
-
if (*delay_on == 0 /* ms */ && *delay_off == 0 /* ms */) {
/* Special case: the leds subsystem requested us to
* chose one user friendly blinking of the LED, and
@@ -142,8 +135,6 @@ static int clevo_mail_led_blink(struct led_classdev *led_cdev,
*delay_on, *delay_off);
}

- i8042_unlock_chip();
-
return status;
}

diff --git a/drivers/platform/x86/acer-wmi.c b/drivers/platform/x86/acer-wmi.c
index 60c18f21588dd..6cb6f800503b2 100644
--- a/drivers/platform/x86/acer-wmi.c
+++ b/drivers/platform/x86/acer-wmi.c
@@ -1044,9 +1044,7 @@ static acpi_status WMID_set_u32(u32 value, u32 cap)
return AE_BAD_PARAMETER;
if (quirks->mailled == 1) {
param = value ? 0x92 : 0x93;
- i8042_lock_chip();
i8042_command(&param, 0x1059);
- i8042_unlock_chip();
return 0;
}
break;
diff --git a/drivers/platform/x86/amilo-rfkill.c b/drivers/platform/x86/amilo-rfkill.c
index 493e169c8f615..ce68d0c9ac29f 100644
--- a/drivers/platform/x86/amilo-rfkill.c
+++ b/drivers/platform/x86/amilo-rfkill.c
@@ -30,9 +30,7 @@ static int amilo_a1655_rfkill_set_block(void *data, bool blocked)
u8 param = blocked ? A1655_WIFI_OFF : A1655_WIFI_ON;
int rc;

- i8042_lock_chip();
rc = i8042_command(&param, A1655_WIFI_COMMAND);
- i8042_unlock_chip();
return rc;
}

diff --git a/include/linux/i8042.h b/include/linux/i8042.h
index 0261e2fb36364..1c081081c161d 100644
--- a/include/linux/i8042.h
+++ b/include/linux/i8042.h
@@ -55,8 +55,6 @@ struct serio;

#if defined(CONFIG_SERIO_I8042) || defined(CONFIG_SERIO_I8042_MODULE)

-void i8042_lock_chip(void);
-void i8042_unlock_chip(void);
int i8042_command(unsigned char *param, int command);
int i8042_install_filter(bool (*filter)(unsigned char data, unsigned char str,
struct serio *serio));
@@ -65,14 +63,6 @@ int i8042_remove_filter(bool (*filter)(unsigned char data, unsigned char str,

#else

-static inline void i8042_lock_chip(void)
-{
-}
-
-static inline void i8042_unlock_chip(void)
-{
-}
-
static inline int i8042_command(unsigned char *param, int command)
{
return -ENODEV;
--
2.28.0.297.g1956fa8f8d-goog