On Fri, Jan 25, 2019 at 10:15:40AM +0800, Wei Hu (Xavier) wrote:
>
>
> On 2019/1/25 2:31, Jason Gunthorpe wrote:
> > On Thu, Jan 24, 2019 at 11:13:29AM +0800, Wei Hu (Xavier) wrote:
> >>
> >> On 2019/1/24 6:40, Jason Gunthorpe wrote:
> >>> On Sat, Jan 19, 2019 at 11:36:06AM +0800, Wei Hu (Xavier) wrote:
> >>>
> >>>> +static int hns_roce_v2_cmd_hw_resetting(struct hns_roce_dev *hr_dev,
> >>>> + unsigned long instance_stage,
> >>>> + unsigned long reset_stage)
> >>>> +{
> >>>> + struct hns_roce_v2_priv *priv = (struct hns_roce_v2_priv *)hr_dev->priv;
> >>>> + struct hnae3_handle *handle = priv->handle;
> >>>> + const struct hnae3_ae_ops *ops = handle->ae_algo->ops;
> >>>> + unsigned long end;
> >>>> +
> >>>> + /* When hardware reset is detected, we should stop sending mailbox&cmq
> >>>> + * to hardware, and wait until hardware reset finished. If now
> >>>> + * in .init_instance() function, we should exit with error. If now at
> >>>> + * HNAE3_INIT_CLIENT stage of soft reset process, we should exit with
> >>>> + * error, and then HNAE3_INIT_CLIENT related process can rollback the
> >>>> + * operation like notifing hardware to free resources, HNAE3_INIT_CLIENT
> >>>> + * related process will exit with error to notify NIC driver to
> >>>> + * reschedule soft reset process once again.
> >>>> + */
> >>>> + end = msecs_to_jiffies(HNS_ROCE_V2_HW_RST_TIMEOUT) + jiffies;
> >>>> + while (ops->get_hw_reset_stat(handle) && time_before(jiffies, end))
> >>>> + udelay(1);
> >>> I thought you were getting rid of these loops?
> >> Hi, Jason
> >>
> >> Upper applications maybe notify driver to issue mailbox or CMD
> >> commands to hardware, some commands used to cancel resources,
> >> destory bt/destory cq/unreg mr/destory qp etc. when such
> >> commands are executed successfully, the hardware engine will
> >> no longer access some memory registered by the driver.
> >>
> >> When reset occurs, it is possible for upper applications notify driver
> >> to issue mailbox or CMD commands, we need to wait until hardware
> >> reset finished to ensure that hardware no longer accesses related
> >> memory.
> > You should not wait for things using loops like the above.
> Hi, Jason
>
> Are your comments foucsing on udelay? If not, thanks for your detail
> information.
> In hns3 RoCE driver, some CMQ/mailbox operation are called inside
> the lock,
> we can't use msleep in the lock, otherwise it will cause deadlock.
> When reset occurs, RDMA service cannot be provided normally, I think
> in this
> case using udelay will not have a great impact.
You should not use any kind of sleep call in a loop like this.
Jason
