Re: [PATCH rdma-next 3/3] RDMA/hns: Modify hns RoCE device's name

From: Wei Hu (Xavier)
Date: Mon Nov 26 2018 - 03:34:27 EST

On 2018/11/26 11:13, Jason Gunthorpe wrote:
> On Sat, Nov 24, 2018 at 09:01:19PM +0800, Wei Hu (Xavier) wrote:
>> On 2018/11/24 4:39, Jason Gunthorpe wrote:
>>> On Fri, Nov 23, 2018 at 11:14:25PM +0800, Wei Hu (Xavier) wrote:
>>>> This patch modifies the name of hns RoCE device's name in order
>>>> to ensure that the name is consistent before and after reset.
>>>> Signed-off-by: Wei Hu (Xavier) <xavier.huwei@xxxxxxxxxx>
>>>> drivers/infiniband/hw/hns/hns_roce_device.h | 1 +
>>>> drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 3 +++
>>>> drivers/infiniband/hw/hns/hns_roce_main.c | 4 +++-
>>>> 3 files changed, 7 insertions(+), 1 deletion(-)
>>>> diff --git a/drivers/infiniband/hw/hns/hns_roce_device.h b/drivers/infiniband/hw/hns/hns_roce_device.h
>>>> index 259977b..a8cfe76 100644
>>>> +++ b/drivers/infiniband/hw/hns/hns_roce_device.h
>>>> @@ -954,6 +954,7 @@ struct hns_roce_dev {
>>>> struct pci_dev *pci_dev;
>>>> struct device *dev;
>>>> struct hns_roce_uar priv_uar;
>>>> + char name[IB_DEVICE_NAME_MAX];
>>>> const char *irq_names[HNS_ROCE_MAX_IRQ_NUM];
>>>> spinlock_t sm_lock;
>>>> spinlock_t bt_cmd_lock;
>>>> diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
>>>> index 1d639a0..678c7ec 100644
>>>> +++ b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
>>>> @@ -6110,6 +6110,9 @@ static int hns_roce_hw_v2_get_cfg(struct hns_roce_dev *hr_dev,
>>>> hr_dev->irq[i] = pci_irq_vector(handle->pdev,
>>>> i + handle->rinfo.base_vector);
>>>> + snprintf(hr_dev->name, IB_DEVICE_NAME_MAX, "hns%s",
>>>> + handle->rinfo.netdev->name);
>>> Why is this making up its own driver name? How is this avoiding
>>> colliding with an existing name?
>>> This is very dangerous since we now have device renaming, the driver
>>> could fail to load with no recovery.
>> Hi, Jason
>> The NIC driver notifies the RoCE driver to perform reset related
>> processing by calling the .reset_notify() interface registered by the
>> RoCE driver. If the RoCE reset processing fails, .reset_notify()
>> returns non-zero, and then hns NIC driver will reschedule the
>> reset task again.
>> The current hardware version in hip08 SoC cannot support
>> after reset process the application still communicates with the
>> resources like QP requested before reset. In RoCE reset process,
>> we will release the resources through ib_unregister_device, after
>> the hardware reset is completed, driver will re-execute
>> ib_register_device.
>> Currently, we find that the ib_device's name after reset
>> and the one before reset may be different. We can specify the
>> device name to solve this problem.
> No, now you just have unsolved races.
> If you want to reset like this then you will need to do some kind of
> revision to the IB core code to not loose the name assigned to the
> device and not hacks like this.
Hi, Jason

In fact, We only specified the name of the ib_device to be generated
calling ib_register_device on the hip08 SoC, and doesn't modify its name
during the existence of ib_device.

In this example, if you always use hns_%d when registering, I think that
no matter how you modify IB core code, we can't solve this problem. We
need to specify the name of the ib_device device when calling
ib_register_device, and this name should be unique in the OS.

The NIC and the RoCE hardware engine share the function On the hip08
The NIC driver will execute register_netdev firstly, and then the RoCE
driver will
execute ib_register_device. In the following statement, where
handle->rinfo.netdev->name is the name of the corresponding net_device
this will ensure the uniqueness of the hnsXXX ib_device's name on the OS.

snprintf(hr_dev->name, IB_DEVICE_NAME_MAX, "hns%s",

Best Regards
> Jason
> .