linux-kernel - Re: [PATCH net 7/7] net: hns3: fix kernel crash when devlink reload during vf initialization

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Message-ID: <Ziew8wLJ180m9PR6@nanopsycho>
Date: Tue, 23 Apr 2024 15:00:35 +0200
From: Jiri Pirko <jiri@...nulli.us>
To: Jijie Shao <shaojijie@...wei.com>
Cc: yisen.zhuang@...wei.com, salil.mehta@...wei.com, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	shenjian15@...wei.com, wangjie125@...wei.com,
	liuyonglong@...wei.com, chenhao418@...wei.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net 7/7] net: hns3: fix kernel crash when devlink reload
 during vf initialization

Tue, Apr 23, 2024 at 01:51:21PM CEST, shaojijie@...wei.com wrote:
>
>on 2024/4/22 22:18, Jiri Pirko wrote:
>> Mon, Apr 22, 2024 at 03:43:27PM CEST,shaojijie@...wei.com  wrote:
>> > From: Yonglong Liu<liuyonglong@...wei.com>
>> > 
>> > The devlink reload process will access the hardware resources,
>> > but the register operation is done before the hardware is initialized.
>> > So, processing the devlink reload during initialization may lead to kernel
>> > crash. This patch fixes this by taking devl_lock during initialization.
>> > 
>> > Fixes: cd6242991d2e ("net: hns3: add support for registering devlink for VF")
>> > Signed-off-by: Yonglong Liu<liuyonglong@...wei.com>
>> > Signed-off-by: Jijie Shao<shaojijie@...wei.com>
>> > ---
>> > drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.c | 4 ++++
>> > 1 file changed, 4 insertions(+)
>> > 
>> > diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.c b/drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.c
>> > index 08db8e84be4e..3ee41943d15f 100644
>> > --- a/drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.c
>> > +++ b/drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.c
>> > @@ -2849,6 +2849,8 @@ static int hclgevf_init_hdev(struct hclgevf_dev *hdev)
>> > 	if (ret)
>> > 		goto err_devlink_init;
>> > 
>> Hmm, what if reload happens here? I think that you don't fix the issue,
>> rather just narrowing the race window.
>
>Yes the issue still occurs.
>
>> Why don't you rather calle devlink_register at the end of this function?
>
>We intended to fix this issue with minimal changes.

I'm not suggesting anything that would mean the opposite.


>But now it seems that we can only call devlink_register at the end of this function

I don't follow. Is that a question? That is what I suggested.


>
>> Also, parallel to this patch, why don't you register devlink port of
>> flavour "virtual" for this VF?
>
>I'm sorry, I'm not sure what "flavour "virtual"" means?

git grep DEVLINK_PORT_FLAVOUR_VIRTUAL


>And How can we use it? If it is useful, I can send another patch to optimize the code.

Please do.


>
>Tnanks,
>Jijie Shao