linux-kernel - Re: [PATCH] ACPI: fan: fix warning with CONFIG_DEBUG_LOCK

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Message-ID: <CAJZ5v0hPBwynaTVmD-2_wpv87f5_DLEz1Bc4Qx8aUgunrRRn-g@mail.gmail.com>
Date:   Mon, 7 Dec 2020 14:14:11 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Zhang Rui <rui.zhang@...el.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        "open list:ACPI FAN DRIVER" <linux-acpi@...r.kernel.org>
Subject: Re: [PATCH] ACPI: fan: fix warning with CONFIG_DEBUG_LOCK_ALLOC

On Fri, Dec 4, 2020 at 7:27 PM Pierre-Louis Bossart
<pierre-louis.bossart@...ux.intel.com> wrote:
>
> On a TigerLake device with CONFIG_DEBUG_LOCK_ALLOC the following
> warning is thrown:
>
> [   13.784413] BUG: key ffff88810ea5a080 has not been registered!
> [   13.784722] DEBUG_LOCKS_WARN_ON(1)
> [   13.784737] WARNING: CPU: 2 PID: 1 at kernel/locking/lockdep.c:4623
> lockdep_init_map_waits+0x25e/0x310
> [   13.787831] Call Trace:
> [   13.787902]  __kernfs_create_file+0xa5/0x180
> [   13.788016]  sysfs_add_file_mode_ns+0x120/0x270
> [   13.788138]  sysfs_create_file_ns+0xcd/0x120
> [   13.788256]  ? sysfs_add_file_mode_ns+0x270/0x270
> [   13.788381]  ? fan_get_max_state+0x70/0x70
> [   13.788491]  ? sort_r+0x1a5/0x200
> [   13.788579]  acpi_fan_probe+0x63b/0x7a0
>
> Dynamically-allocated attributes need to be initialized to make
> lockdep happy, see include/linux/sysfs.h
>
> Fixes: d19e470b6605c ('ACPI: fan: Expose fan performance state information')
> Cc: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> ---
>  drivers/acpi/fan.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/acpi/fan.c b/drivers/acpi/fan.c
> index 66c3983f0ccc..9cab806298ff 100644
> --- a/drivers/acpi/fan.c
> +++ b/drivers/acpi/fan.c
> @@ -357,6 +357,7 @@ static int acpi_fan_get_fps(struct acpi_device *device)
>                 fps->dev_attr.store = NULL;
>                 fps->dev_attr.attr.name = fps->name;
>                 fps->dev_attr.attr.mode = 0444;
> +               sysfs_attr_init(&fps->dev_attr.attr);
>                 status = sysfs_create_file(&device->dev.kobj, &fps->dev_attr.attr);
>                 if (status) {
>                         int j;
> --

This has been fixed in the mainline already AFAICS, by commit
7dc7a8b04f3d ("ACPI: fan: Initialize performance state sysfs
attribute").