linux-kernel - Re: [PATCH] ipmi_si: fix unexpected driver unregister warning

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Message-ID: <20190517161821.GB11017@minyard.net>
Date:   Fri, 17 May 2019 11:18:21 -0500
From:   Corey Minyard <minyard@....org>
To:     Kefeng Wang <wangkefeng.wang@...wei.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Hulk Robot <hulkci@...wei.com>
Subject: Re: [PATCH] ipmi_si: fix unexpected driver unregister warning

On Fri, May 17, 2019 at 06:12:44PM +0800, Kefeng Wang wrote:
> If ipmi_si_platform_init()->platform_driver_register() fails,
> platform_driver_unregister() called unconditionally will trigger
> following warning,
> 
> ipmi_platform: Unable to register driver: -12
> ------------[ cut here ]------------
> Unexpected driver unregister!
> WARNING: CPU: 1 PID: 7210 at drivers/base/driver.c:193 driver_unregister+0x60/0x70 drivers/base/driver.c:193
> 
> Fix it by adding platform_registered variable, only unregister platform
> driver when it is already successfully registered.

This is good, but have you found out why the driver was unable to
register in the first place?  That really shouldn't happen.

This patch is queued for 5.3.

-corey

> 
> Reported-by: Hulk Robot <hulkci@...wei.com>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
> ---
>  drivers/char/ipmi/ipmi_si_platform.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/ipmi/ipmi_si_platform.c b/drivers/char/ipmi/ipmi_si_platform.c
> index f2a91c4d8cab..0cd849675d99 100644
> --- a/drivers/char/ipmi/ipmi_si_platform.c
> +++ b/drivers/char/ipmi/ipmi_si_platform.c
> @@ -19,6 +19,7 @@
>  #include "ipmi_si.h"
>  #include "ipmi_dmi.h"
>  
> +static bool platform_registered;
>  static bool si_tryplatform = true;
>  #ifdef CONFIG_ACPI
>  static bool          si_tryacpi = true;
> @@ -469,9 +470,12 @@ void ipmi_si_platform_init(void)
>  	int rv = platform_driver_register(&ipmi_platform_driver);
>  	if (rv)
>  		pr_err("Unable to register driver: %d\n", rv);
> +	else
> +		platform_registered = true;
>  }
>  
>  void ipmi_si_platform_shutdown(void)
>  {
> -	platform_driver_unregister(&ipmi_platform_driver);
> +	if (platform_registered)
> +		platform_driver_unregister(&ipmi_platform_driver);
>  }
> -- 
> 2.20.1
>