linux-kernel - Re: [PATCH v2 2/4] uacce: fix isolate sysfs check condition

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Message-ID: <2025091633-antacid-gluten-0a61@gregkh>
Date: Tue, 16 Sep 2025 17:15:26 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Chenghai Huang <huangchenghai2@...wei.com>
Cc: zhangfei.gao@...aro.org, wangzhou1@...ilicon.com,
	linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
	linuxarm@...neuler.org, fanghao11@...wei.com, shenyang39@...wei.com,
	liulongfang@...wei.com, qianweili@...wei.com
Subject: Re: [PATCH v2 2/4] uacce: fix isolate sysfs check condition

On Tue, Sep 16, 2025 at 10:48:09PM +0800, Chenghai Huang wrote:
> The uacce supports device isolation feature. If the driver
> implements the isolate_err_threshold_read and
> isolate_err_threshold_write callbacks, the uacce will create sysfs
> files. Users can read and configure isolation policies through
> sysfs. Currently, if either isolate_err_threshold_read or
> isolate_err_threshold_write callback exists, sysfs files are
> created.
> 
> However, accessing a non-existent callback may cause a system panic.

Where is the callback happening that fails?  Shouldn't that be checked
instead of doing this change?

> Therefore, sysfs files are only created when both
> isolate_err_threshold_read and isolate_err_threshold_write are
> present.

What if a device only has 1?  That should still work properly?

And why not just create the file if it is going to be used, that is the
real solution here.

thanks,

greg k-h