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Date:   Tue, 19 Jan 2021 09:26:55 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc:     rjw@rjwysocki.net, AceLan Kao <acelan.kao@canonical.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Len Brown <lenb@kernel.org>,
        "open list:ACPI" <linux-acpi@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ACPI / device_sysfs: Use OF_MODALIAS for "compatible"
 modalias
Message-ID: <YAaXz9Pg5x3DsCs3@kroah.com>
References: <20210119081513.300938-1-kai.heng.feng@canonical.com>
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On Tue, Jan 19, 2021 at 04:15:13PM +0800, Kai-Heng Feng wrote:
> Commit 8765c5ba1949 ("ACPI / scan: Rework modalias creation when
> "compatible" is present") may create two "MODALIAS=" in uevent file if
> conditions are met.
> 
> This breaks systemd-udevd, which assumes each "key" in uevent file is
> unique. The internal implementation of systemd-udevd overwrites the
> first MODALIAS with the second one, so its kmod rule doesn't load driver
> for the first MODALIAS.
> 
> Right now it doesn't seem to have any user relies on the second
> MODALIAS, so change it to OF_MODALIAS to workaround the issue.
> 
> Reference: https://github.com/systemd/systemd/pull/18163
> Fixes: 8765c5ba1949 ("ACPI / scan: Rework modalias creation when "compatible" is present")
> Cc: AceLan Kao <acelan.kao@canonical.com>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
> Cc: Mika Westerberg <mika.westerberg@linux.intel.com>,
> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
>  drivers/acpi/device_sysfs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/device_sysfs.c b/drivers/acpi/device_sysfs.c
> index 96869f1538b9..c92b671cb816 100644
> --- a/drivers/acpi/device_sysfs.c
> +++ b/drivers/acpi/device_sysfs.c
> @@ -260,7 +260,7 @@ int __acpi_device_uevent_modalias(struct acpi_device *adev,
>  	if (!adev->data.of_compatible)
>  		return 0;
>  
> -	if (len > 0 && add_uevent_var(env, "MODALIAS="))
> +	if (len > 0 && add_uevent_var(env, "OF_MODALIAS="))

Who will use OF_MODALIAS and where have you documented it?

thanks,

greg k-h