linux-kernel - Re: [PATCH] i801_smbus: clear SMBALERT status bit and disable SMBALERT interrupt

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Date:   Mon, 16 Sep 2019 09:29:27 +0000
From:   "Sverdlin, Alexander (Nokia - DE/Ulm)" <alexander.sverdlin@...ia.com>
To:     Jean Delvare <jdelvare@...e.de>,
        "Xu, Lingyan (NSB - CN/Hangzhou)" <lingyan.xu@...ia-sbell.com>
CC:     "Adamski, Krzysztof (Nokia - PL/Wroclaw)" 
        <krzysztof.adamski@...ia.com>,
        "Wiebe, Wladislav (Nokia - DE/Ulm)" <wladislav.wiebe@...ia.com>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] i801_smbus: clear SMBALERT status bit and disable
 SMBALERT interrupt

Hi Jean,

On 05/09/2019 14:57, Jean Delvare wrote:
> If this is of any value to you, I tried implementing it in i2c-i801 a
> few days ago. I can't really test it though as I don't have any device
> which triggers an alert on my system, but I am sharing it with you if
> you want to give it a try. You would still need to write the code in
> the slave driver.

and I forgot another issue:

> @@ -1897,8 +1956,10 @@ static void i801_remove(struct pci_dev *
>  	pm_runtime_forbid(&dev->dev);
>  	pm_runtime_get_noresume(&dev->dev);
>  
> -	i801_disable_host_notify(priv);
> +	i801_restore_slvcmd(priv);
>  	i801_del_mux(priv);
> +	if (priv->ara)
> +		i2c_unregister_device(priv->ara);

to me it looks like a race with IRQ handler (IRQ is only disabled *after*
remove()), it can still attempt to use freed ARA device after this line. 

>  	i2c_del_adapter(&priv->adapter);
>  	i801_acpi_remove(priv);
>  	pci_write_config_byte(dev, SMBHSTCFG, priv->original_hstcfg);

-- 
Best regards,
Alexander Sverdlin.