linux-kernel - Re: [PATCH for-rc 2/9] RDMA/hns: Fix a long wait for cmdq event during reset

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20240708073315.GC6788@unreal>
Date: Mon, 8 Jul 2024 10:33:15 +0300
From: Leon Romanovsky <leon@...nel.org>
To: Junxian Huang <huangjunxian6@...ilicon.com>
Cc: jgg@...pe.ca, linux-rdma@...r.kernel.org, linuxarm@...wei.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH for-rc 2/9] RDMA/hns: Fix a long wait for cmdq event
 during reset

On Mon, Jul 08, 2024 at 02:50:50PM +0800, Junxian Huang wrote:
> 
> 
> On 2024/7/8 13:38, Leon Romanovsky wrote:
> > On Mon, Jul 08, 2024 at 10:29:54AM +0800, Junxian Huang wrote:
> >>
> >>
> >> On 2024/7/7 16:30, Leon Romanovsky wrote:
> >>> On Fri, Jul 05, 2024 at 04:59:30PM +0800, Junxian Huang wrote:
> >>>> From: wenglianfa <wenglianfa@...wei.com>
> >>>>
> >>>> During reset, cmdq events won't be reported, leading to a long and
> >>>> unnecessary wait. Notify all the cmdqs to stop waiting at the beginning
> >>>> of reset.
> >>>>
> >>>> Fixes: 9a4435375cd1 ("IB/hns: Add driver files for hns RoCE driver")
> >>>> Signed-off-by: wenglianfa <wenglianfa@...wei.com>
> >>>> Signed-off-by: Junxian Huang <huangjunxian6@...ilicon.com>
> >>>> ---
> >>>>  drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 18 ++++++++++++++++++
> >>>>  1 file changed, 18 insertions(+)
> >>>>
> >>>> diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
> >>>> index a5d746a5cc68..ff135df1a761 100644
> >>>> --- a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
> >>>> +++ b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
> >>>> @@ -6977,6 +6977,21 @@ static void hns_roce_hw_v2_uninit_instance(struct hnae3_handle *handle,
> >>>>  
> >>>>  	handle->rinfo.instance_state = HNS_ROCE_STATE_NON_INIT;
> >>>>  }
> >>>> +
> >>>> +static void hns_roce_v2_reset_notify_cmd(struct hns_roce_dev *hr_dev)
> >>>> +{
> >>>> +	struct hns_roce_cmdq *hr_cmd = &hr_dev->cmd;
> >>>> +	int i;
> >>>> +
> >>>> +	if (!hr_dev->cmd_mod)
> >>>
> >>> What prevents cmd_mod from being changed?
> >>>
> >>
> >> It's set when the device is being initialized, and won't be changed after that.
> > 
> > This is exactly the point, you are assuming that the device is already
> > ininitialized or not initialized at all. What prevents hns_roce_v2_reset_notify_cmd()
> > from being called in the middle of initialization?
> > 
> > Thanks
> > 
> 
> This is ensured by hns3 NIC driver.
> 
> Initialization and reset of hns RoCE are both called by hns3. It will check the state
> of RoCE device (see line 3798), and notify RoCE device to reset (hns_roce_v2_reset_notify_cmd()
> is called) only if the RoCE device has been already initialized:

So why do you have "if (!hr_dev->cmd_mod)" check in the code?

Thanks

> 
>  3791 static int hclge_notify_roce_client(struct hclge_dev *hdev,
>  3792                                     enum hnae3_reset_notify_type type)
>  3793 {
>  3794         struct hnae3_handle *handle = &hdev->vport[0].roce;
>  3795         struct hnae3_client *client = hdev->roce_client;
>  3796         int ret;
>  3797
>  3798         if (!test_bit(HCLGE_STATE_ROCE_REGISTERED, &hdev->state) || !client)
>  3799                 return 0;
>  3800
>  3801         if (!client->ops->reset_notify)
>  3802                 return -EOPNOTSUPP;
>  3803
>  3804         ret = client->ops->reset_notify(handle, type);
>  3805         if (ret)
>  3806                 dev_err(&hdev->pdev->dev, "notify roce client failed %d(%d)",
>  3807                         type, ret);
>  3808
>  3809         return ret;
>  3810 }
> 
> And the bit is set (see line 11246) after the initialization has been done (line 11242):
> 
> 11224 static int hclge_init_roce_client_instance(struct hnae3_ae_dev *ae_dev,
> 11225                                            struct hclge_vport *vport)
> 11226 {
> 11227         struct hclge_dev *hdev = ae_dev->priv;
> 11228         struct hnae3_client *client;
> 11229         int rst_cnt;
> 11230         int ret;
> 11231
> 11232         if (!hnae3_dev_roce_supported(hdev) || !hdev->roce_client ||
> 11233             !hdev->nic_client)
> 11234                 return 0;
> 11235
> 11236         client = hdev->roce_client;
> 11237         ret = hclge_init_roce_base_info(vport);
> 11238         if (ret)
> 11239                 return ret;
> 11240
> 11241         rst_cnt = hdev->rst_stats.reset_cnt;
> 11242         ret = client->ops->init_instance(&vport->roce);
> 11243         if (ret)
> 11244                 return ret;
> 11245
> 11246         set_bit(HCLGE_STATE_ROCE_REGISTERED, &hdev->state);
> 11247         if (test_bit(HCLGE_STATE_RST_HANDLING, &hdev->state) ||
> 11248             rst_cnt != hdev->rst_stats.reset_cnt) {
> 11249                 ret = -EBUSY;
> 11250                 goto init_roce_err;
> 11251         }
> 
> Junxian
> 
> >>
> >> Junxian
> >>
> >>>> +		return;
> >>>> +
> >>>> +	for (i = 0; i < hr_cmd->max_cmds; i++) {
> >>>> +		hr_cmd->context[i].result = -EBUSY;
> >>>> +		complete(&hr_cmd->context[i].done);
> >>>> +	}
> >>>> +}
> >>>> +
> >>>>  static int hns_roce_hw_v2_reset_notify_down(struct hnae3_handle *handle)
> >>>>  {
> >>>>  	struct hns_roce_dev *hr_dev;
> >>>> @@ -6997,6 +7012,9 @@ static int hns_roce_hw_v2_reset_notify_down(struct hnae3_handle *handle)
> >>>>  	hr_dev->dis_db = true;
> >>>>  	hr_dev->state = HNS_ROCE_DEVICE_STATE_RST_DOWN;
> >>>>  
> >>>> +	/* Complete the CMDQ event in advance during the reset. */
> >>>> +	hns_roce_v2_reset_notify_cmd(hr_dev);
> >>>> +
> >>>>  	return 0;
> >>>>  }
> >>>>  
> >>>> -- 
> >>>> 2.33.0
> >>>>
> >>
>