Date:   Tue, 11 May 2021 13:24:44 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux ACPI <linux-acpi@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI: scan: Rearrange dep_unmet initialization

Hi Rafael,

On 5/10/21 7:53 PM, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> The dep_unmet field in struct acpi_device is used to store the
> number of unresolved _DEP dependencies (that is, operation region
> dependencies for which there are no drivers present) for the ACPI
> device object represented by it.
> 
> That field is initialized to 1 for all ACPI device objects in
> acpi_add_single_object(), via acpi_init_device_object(), so as to
> avoid evaluating _STA prematurely for battery device objects in
> acpi_scan_init_status(), and it is "fixed up" in acpi_bus_check_add()
> after the acpi_add_single_object() called by it has returned.
> 
> This is not particularly straightforward and causes dep_unmet to
> remain 1 for device objects without dependencies created by invoking
> acpi_add_single_object() directly, outside acpi_bus_check_add().
> 
> For this reason, rearrange acpi_add_single_object() to initialize
> dep_unmet completely before calling acpi_scan_init_status(), which
> requires passing one extra bool argument to it, and update all of
> its callers accordingly.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Thanks, one small nitpick below.

> ---
>  drivers/acpi/scan.c |   62 +++++++++++++++++++++++++---------------------------
>  1 file changed, 30 insertions(+), 32 deletions(-)
> 
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -1670,8 +1670,22 @@ void acpi_init_device_object(struct acpi
>  	device_initialize(&device->dev);
>  	dev_set_uevent_suppress(&device->dev, true);
>  	acpi_init_coherency(device);
> -	/* Assume there are unmet deps to start with. */
> -	device->dep_unmet = 1;
> +}
> +
> +static void acpi_scan_dep_init(struct acpi_device *adev)
> +{
> +	struct acpi_dep_data *dep;
> +
> +	adev->dep_unmet = 0;

Now that we don't set dep_unmet to 1 in acpi_init_device_object()
anymore this line is no longer necessary.

dep_unmet is set to 0 by the kzalloc of the adev and we are already
relying on that in the case where the dep_init parameter to
acpi_add_single_object() is false.

But if you want to keep this that is fine too, either way
this patch looks good to me:

Reviewed-by: Hans de Goede <hdegoede@...hat.com>

Regards,

Hans








> +
> +	mutex_lock(&acpi_dep_list_lock);
> +
> +	list_for_each_entry(dep, &acpi_dep_list, node) {
> +		if (dep->consumer == adev->handle)
> +			adev->dep_unmet++;
> +	}
> +
> +	mutex_unlock(&acpi_dep_list_lock);
>  }
>  
>  void acpi_device_add_finalize(struct acpi_device *device)
> @@ -1687,7 +1701,7 @@ static void acpi_scan_init_status(struct
>  }
>  
>  static int acpi_add_single_object(struct acpi_device **child,
> -				  acpi_handle handle, int type)
> +				  acpi_handle handle, int type, bool dep_init)
>  {
>  	struct acpi_device *device;
>  	int result;
> @@ -1702,8 +1716,12 @@ static int acpi_add_single_object(struct
>  	 * acpi_bus_get_status() and use its quirk handling.  Note that
>  	 * this must be done before the get power-/wakeup_dev-flags calls.
>  	 */
> -	if (type == ACPI_BUS_TYPE_DEVICE || type == ACPI_BUS_TYPE_PROCESSOR)
> +	if (type == ACPI_BUS_TYPE_DEVICE || type == ACPI_BUS_TYPE_PROCESSOR) {
> +		if (dep_init)
> +			acpi_scan_dep_init(device);
> +
>  		acpi_scan_init_status(device);
> +	}
>  
>  	acpi_bus_get_power_flags(device);
>  	acpi_bus_get_wakeup_device_flags(device);
> @@ -1885,22 +1903,6 @@ static u32 acpi_scan_check_dep(acpi_hand
>  	return count;
>  }
>  
> -static void acpi_scan_dep_init(struct acpi_device *adev)
> -{
> -	struct acpi_dep_data *dep;
> -
> -	adev->dep_unmet = 0;
> -
> -	mutex_lock(&acpi_dep_list_lock);
> -
> -	list_for_each_entry(dep, &acpi_dep_list, node) {
> -		if (dep->consumer == adev->handle)
> -			adev->dep_unmet++;
> -	}
> -
> -	mutex_unlock(&acpi_dep_list_lock);
> -}
> -
>  static bool acpi_bus_scan_second_pass;
>  
>  static acpi_status acpi_bus_check_add(acpi_handle handle, bool check_dep,
> @@ -1948,19 +1950,15 @@ static acpi_status acpi_bus_check_add(ac
>  		return AE_OK;
>  	}
>  
> -	acpi_add_single_object(&device, handle, type);
> -	if (!device)
> -		return AE_CTRL_DEPTH;
> -
> -	acpi_scan_init_hotplug(device);
>  	/*
>  	 * If check_dep is true at this point, the device has no dependencies,
>  	 * or the creation of the device object would have been postponed above.
>  	 */
> -	if (check_dep)
> -		device->dep_unmet = 0;
> -	else
> -		acpi_scan_dep_init(device);
> +	acpi_add_single_object(&device, handle, type, !check_dep);
> +	if (!device)
> +		return AE_CTRL_DEPTH;
> +
> +	acpi_scan_init_hotplug(device);
>  
>  out:
>  	if (!*adev_p)
> @@ -2222,7 +2220,7 @@ int acpi_bus_register_early_device(int t
>  	struct acpi_device *device = NULL;
>  	int result;
>  
> -	result = acpi_add_single_object(&device, NULL, type);
> +	result = acpi_add_single_object(&device, NULL, type, false);
>  	if (result)
>  		return result;
>  
> @@ -2242,7 +2240,7 @@ static int acpi_bus_scan_fixed(void)
>  		struct acpi_device *device = NULL;
>  
>  		result = acpi_add_single_object(&device, NULL,
> -						ACPI_BUS_TYPE_POWER_BUTTON);
> +						ACPI_BUS_TYPE_POWER_BUTTON, false);
>  		if (result)
>  			return result;
>  
> @@ -2258,7 +2256,7 @@ static int acpi_bus_scan_fixed(void)
>  		struct acpi_device *device = NULL;
>  
>  		result = acpi_add_single_object(&device, NULL,
> -						ACPI_BUS_TYPE_SLEEP_BUTTON);
> +						ACPI_BUS_TYPE_SLEEP_BUTTON, false);
>  		if (result)
>  			return result;
>  
> 
> 
> 

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