Re: [PATCH v2 1/2] Input: i8042 - Prevent intermixing i8042 commands

From: Hans de Goede
Date: Wed Oct 28 2020 - 17:37:10 EST

Hi,

Quick self intro: I have take over drivers/platform/x86
maintainership from Andy; and I'm working my way through
the backlog of old patches in patchwork:
https://patchwork.kernel.org/project/platform-driver-x86/list/

On 8/27/20 10:41 PM, Raul E Rangel wrote:
> 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.
>
> Link: https://lore.kernel.org/linux-input/CAHQZ30ANTeM-pgdYZ4AbgxsnevBJnJgKZ1Kg+Uy8oSXZUvz=og@xxxxxxxxxxxxxx
> Signed-off-by: Raul E Rangel <rrangel@xxxxxxxxxxxx>

Patch looks good to me, you can add my:

Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx>

(for both the drivers/platform/x86 bits and in general).

Dmitry, feel free to merge this through the input tree, I don't
expect the touched pdx86 parts to see any changes this cycle.

Regards,

Hans





> ---
> Tested this on a device with only a PS/2 keyboard. I was able to do
> 1200+ suspend/resume cycles.
>
> Also tested this on a device with a PS/2 keyboard and a PS/2 mouse.
> I was able to do 250+ iterations with out problems.
>
> Changes in v2:
> - Fixed bad indent
> - Added Link: tag
> - Removed left over rc variable
>
> 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 | 6 +-----
> include/linux/i8042.h | 10 ----------
> 5 files changed, 15 insertions(+), 41 deletions(-)
>
> diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
> index 0dddf273afd94..65ca6b47f41e8 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..c981c6e07ff94 100644
> --- a/drivers/platform/x86/amilo-rfkill.c
> +++ b/drivers/platform/x86/amilo-rfkill.c
> @@ -28,12 +28,8 @@
> 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;
> + return i8042_command(&param, A1655_WIFI_COMMAND);
> }
>
> static const struct rfkill_ops amilo_a1655_rfkill_ops = {
> 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;
>