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Message-ID: <2dd4f820-8b94-4e9b-909c-b43cb40bfc99@redhat.com>
Date: Mon, 8 Apr 2024 11:21:00 +0200
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Subject: Re: [PATCH] platform/x86: quickstart: Fix race condition when
 reporting input event
To: Armin Wolf <W_Armin@gmx.de>, ilpo.jarvinen@linux.intel.com
Cc: rafael@kernel.org, linux-acpi@vger.kernel.org,
 platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20240327214524.123935-1-W_Armin@gmx.de>
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From: Hans de Goede <hdegoede@redhat.com>
In-Reply-To: <20240327214524.123935-1-W_Armin@gmx.de>
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Hi,

On 3/27/24 10:45 PM, Armin Wolf wrote:
> Since commit e2ffcda16290 ("ACPI: OSL: Allow Notify () handlers to run
> on all CPUs"), the ACPI core allows multiple notify calls to be active
> at the same time. This means that two instances of quickstart_notify()
> running at the same time can mess which each others input sequences.
> 
> Fix this by protecting the input sequence with a mutex.
> 
> Compile-tested only.
> 
> Fixes: afd66f2a739e ("platform/x86: Add ACPI quickstart button (PNP0C32) driver")
> Signed-off-by: Armin Wolf <W_Armin@gmx.de>

Thank you for your patch, I've applied this patch to my review-hans 
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.

Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.

Regards,

Hans


> ---
> This applies on the branch "review-hans". Maybe we could somehow
> document the concurrency rules for ACPI notify handlers?
> ---
>  drivers/platform/x86/quickstart.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/platform/x86/quickstart.c b/drivers/platform/x86/quickstart.c
> index ba3a7a25dda7..e40f852d42c1 100644
> --- a/drivers/platform/x86/quickstart.c
> +++ b/drivers/platform/x86/quickstart.c
> @@ -18,6 +18,7 @@
>  #include <linux/input/sparse-keymap.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> +#include <linux/mutex.h>
>  #include <linux/platform_device.h>
>  #include <linux/sysfs.h>
>  #include <linux/types.h>
> @@ -35,6 +36,7 @@
> 
>  struct quickstart_data {
>  	struct device *dev;
> +	struct mutex input_lock;	/* Protects input sequence during notify */
>  	struct input_dev *input_device;
>  	char input_name[32];
>  	char phys[32];
> @@ -73,7 +75,10 @@ static void quickstart_notify(acpi_handle handle, u32 event, void *context)
> 
>  	switch (event) {
>  	case QUICKSTART_EVENT_RUNTIME:
> +		mutex_lock(&data->input_lock);
>  		sparse_keymap_report_event(data->input_device, 0x1, 1, true);
> +		mutex_unlock(&data->input_lock);
> +
>  		acpi_bus_generate_netlink_event(DRIVER_NAME, dev_name(data->dev), event, 0);
>  		break;
>  	default:
> @@ -147,6 +152,13 @@ static void quickstart_notify_remove(void *context)
>  	acpi_remove_notify_handler(handle, ACPI_DEVICE_NOTIFY, quickstart_notify);
>  }
> 
> +static void quickstart_mutex_destroy(void *data)
> +{
> +	struct mutex *lock = data;
> +
> +	mutex_destroy(lock);
> +}
> +
>  static int quickstart_probe(struct platform_device *pdev)
>  {
>  	struct quickstart_data *data;
> @@ -165,6 +177,11 @@ static int quickstart_probe(struct platform_device *pdev)
>  	data->dev = &pdev->dev;
>  	dev_set_drvdata(&pdev->dev, data);
> 
> +	mutex_init(&data->input_lock);
> +	ret = devm_add_action_or_reset(&pdev->dev, quickstart_mutex_destroy, &data->input_lock);
> +	if (ret < 0)
> +		return ret;
> +
>  	/* We have to initialize the device wakeup before evaluating GHID because
>  	 * doing so will notify the device if the button was used to wake the machine
>  	 * from S5.
> --
> 2.39.2
>