From: Zhangfei Gao <zhangfei.gao@linaro.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Herbert Xu <herbert@gondor.apana.org.au>,
jean-philippe <jean-philippe@linaro.org>,
Wangzhou <wangzhou1@hisilicon.com>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
acc@openeuler.org, linux-kernel@vger.kernel.org,
linux-crypto@vger.kernel.org, iommu@lists.linux.dev,
Yang Shen <shenyang39@huawei.com>
Subject: Re: [PATCH v2 1/2] uacce: Handle parent driver module removal
Date: Mon, 27 Jun 2022 22:14:29 +0800 [thread overview]
Message-ID: <9ab01d6b-76c2-885c-2827-57912dee62e0@linaro.org> (raw)
In-Reply-To: <Yrmu9DcNObmraG72@kroah.com>
On 2022/6/27 下午9:21, Greg Kroah-Hartman wrote:
> On Fri, Jun 24, 2022 at 10:21:21PM +0800, Zhangfei Gao wrote:
>> Change cdev owner to parent driver owner, which blocks rmmod parent
>> driver module once fd is opened.
>>
>> Signed-off-by: Yang Shen <shenyang39@huawei.com>
>> Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
>> ---
>> drivers/misc/uacce/uacce.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
>> index 281c54003edc..f82f2dd30e76 100644
>> --- a/drivers/misc/uacce/uacce.c
>> +++ b/drivers/misc/uacce/uacce.c
>> @@ -484,7 +484,7 @@ int uacce_register(struct uacce_device *uacce)
>> return -ENOMEM;
>>
>> uacce->cdev->ops = &uacce_fops;
>> - uacce->cdev->owner = THIS_MODULE;
>> + uacce->cdev->owner = uacce->parent->driver->owner;
> What if parent is not set? What if parent does not have a driver set to
> it yet? Why would a device's parent module control the lifespan of this
> child device's cdev?
Have used try_module_get(uacce->parent->driver->owner) in open, and
module_put in release.
Seems same issue.
>
> This feels wrong and like a layering violation here.
>
> If a parent's module is unloaded, then invalidate the cdev for the
> device when you tear it down before the module is unloaded.
Yes, make sense.
>
> Yes, the interaction between the driver model and a cdev is messy, and
> always tricky (see the recent ksummit discussion about this again, and
> last year's discussion), but that does not mean you should add laying
> violations like this to the codebase. Please fix this properly.
Thanks Greg
Yes, I was in hesitation whether adding the patch 1, but it looks very
simple.
In fact, the patch 2 can cover both removing device and rmmod parent
driver module.
We can just keep patch 2.
Thanks
next prev parent reply other threads:[~2022-06-27 14:15 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-24 14:21 [PATCH v2 0/2] fix uacce concurrency issue of uacce_remove Zhangfei Gao
2022-06-24 14:21 ` [PATCH v2 1/2] uacce: Handle parent driver module removal Zhangfei Gao
2022-06-27 13:21 ` Greg Kroah-Hartman
2022-06-27 14:14 ` Zhangfei Gao [this message]
2022-06-24 14:21 ` [PATCH v2 2/2] uacce: Handle parent device removal Zhangfei Gao
2022-06-24 14:37 ` [PATCH v2 0/2] fix uacce concurrency issue of uacce_remove Greg Kroah-Hartman
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