linux-kernel - Re: [PATCH v4 16/20] ACPI: platform_profile: Make sure all profile handlers agree on profile

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Message-ID: <a2bde9c6-6aa3-445b-b27b-2338d78d132d@gmx.de>
Date: Wed, 6 Nov 2024 21:58:09 +0100
From: Armin Wolf <W_Armin@....de>
To: Mario Limonciello <mario.limonciello@....com>,
 Hans de Goede <hdegoede@...hat.com>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: "Rafael J . Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>,
 Maximilian Luz <luzmaximilian@...il.com>, Lee Chun-Yi <jlee@...e.com>,
 Shyam Sundar S K <Shyam-sundar.S-k@....com>,
 Corentin Chary <corentin.chary@...il.com>, "Luke D . Jones"
 <luke@...nes.dev>, Ike Panhc <ike.pan@...onical.com>,
 Henrique de Moraes Holschuh <hmh@....eng.br>,
 Alexis Belmonte <alexbelm48@...il.com>,
 Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
 Ai Chao <aichao@...inos.cn>, Gergo Koteles <soyer@....hu>,
 open list <linux-kernel@...r.kernel.org>,
 "open list:ACPI" <linux-acpi@...r.kernel.org>,
 "open list:MICROSOFT SURFACE PLATFORM PROFILE DRIVER"
 <platform-driver-x86@...r.kernel.org>,
 "open list:THINKPAD ACPI EXTRAS DRIVER"
 <ibm-acpi-devel@...ts.sourceforge.net>,
 Mark Pearson <mpearson-lenovo@...ebb.ca>,
 Matthew Schwartz <matthew.schwartz@...ux.dev>
Subject: Re: [PATCH v4 16/20] ACPI: platform_profile: Make sure all profile
 handlers agree on profile

Am 05.11.24 um 16:33 schrieb Mario Limonciello:

> If for any reason multiple profile handlers don't agree on the profile
> return the custom profile.
>
> Reviewed-by: Mark Pearson <mpearson-lenovo@...ebb.ca>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
>   drivers/acpi/platform_profile.c | 84 +++++++++++++++++++++------------
>   1 file changed, 53 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/platform_profile.c
> index d8c2d195106c2..7861fccc2e58c 100644
> --- a/drivers/acpi/platform_profile.c
> +++ b/drivers/acpi/platform_profile.c
> @@ -280,55 +280,77 @@ static ssize_t platform_profile_choices_show(struct device *dev,
>   	return _commmon_choices_show(aggregate, buf);
>   }
>
> -static ssize_t platform_profile_show(struct device *dev,
> -					struct device_attribute *attr,
> -					char *buf)
> +/**
> + * _aggregate_profiles - Aggregate the profiles for legacy sysfs interface
> + * @dev: The device
> + * @data: The profile to return
> + * Return: 0 on success, -errno on failure
> + */
> +static int _aggregate_profiles(struct device *dev, void *data)
>   {
> -	enum platform_profile_option profile = PLATFORM_PROFILE_BALANCED;
> +	enum platform_profile_option *profile = data;
> +	enum platform_profile_option val;
>   	int err;
>
> -	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &profile_lock) {
> -		if (!cur_profile)
> -			return -ENODEV;
> +	err = get_class_profile(dev, &val);
> +	if (err)
> +		return err;
>
> -		err = cur_profile->profile_get(cur_profile, &profile);
> -		if (err)
> -			return err;
> -	}
> +	if (*profile != PLATFORM_PROFILE_LAST && *profile != val)
> +		*profile = PLATFORM_PROFILE_CUSTOM;
> +	else
> +		*profile = val;
>
> -	/* Check that profile is valid index */
> -	if (WARN_ON((profile < 0) || (profile >= ARRAY_SIZE(profile_names))))
> -		return -EIO;

Please check the returned value from profile_get() first before doing
the custom platform
profile check.

> +	return 0;
> +}
> +
> +/**
> + * platform_profile_show - Show the current profile for legacy sysfs interface
> + * @dev: The device
> + * @attr: The attribute
> + * @buf: The buffer to write to
> + * Return: The number of bytes written
> + */
> +static ssize_t platform_profile_show(struct device *dev,
> +				     struct device_attribute *attr,
> +				     char *buf)
> +{
> +	enum platform_profile_option profile = PLATFORM_PROFILE_LAST;
> +	int err;
> +
> +	err = class_for_each_device(&platform_profile_class, NULL,
> +				    &profile, _aggregate_profiles);

Missing error handling.

>
>   	return sysfs_emit(buf, "%s\n", profile_names[profile]);
>   }
>
> +/**
> + * platform_profile_store - Set the profile for legacy sysfs interface
> + * @dev: The device
> + * @attr: The attribute
> + * @buf: The buffer to read from
> + * @count: The number of bytes to read
> + * Return: The number of bytes read
> + */
>   static ssize_t platform_profile_store(struct device *dev,
> -			    struct device_attribute *attr,
> -			    const char *buf, size_t count)
> +				      struct device_attribute *attr,
> +				      const char *buf, size_t count)
>   {
> -	int err, i;
> +	int ret;
> +	int i;
>
>   	/* Scan for a matching profile */
>   	i = sysfs_match_string(profile_names, buf);
>   	if (i < 0)
>   		return -EINVAL;
> -
> -	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &profile_lock) {
> -		if (!cur_profile)
> -			return -ENODEV;
> -
> -		/* Check that platform supports this profile choice */
> -		if (!test_bit(i, cur_profile->choices))
> -			return -EOPNOTSUPP;
> -
> -		err = cur_profile->profile_set(cur_profile, i);
> -		if (err)
> -			return err;
> +	if (i == PLATFORM_PROFILE_CUSTOM) {
> +		pr_warn("Custom profile not supported for legacy sysfs interface\n");

This would allow userspace applications to spam the kernel log. Please
just return -EINVAL here
and document this special case inside the interface specification.

Thanks,
Armin Wolf

> +		return -EINVAL;
>   	}
>
> -	sysfs_notify(acpi_kobj, NULL, "platform_profile");
> -	return count;
> +	ret = class_for_each_device(&platform_profile_class, NULL, &i, _store_class_profile);
> +
> +	return ret ? ret : count;
>   }
>
>   static DEVICE_ATTR_RO(platform_profile_choices);