On Tue, Jan 29, 2019 at 10:18:40AM +0800, Wei Hu (Xavier) wrote:
>
>
> On 2019/1/29 2:27, Jason Gunthorpe wrote:
> > On Sat, Jan 26, 2019 at 09:47:42AM +0800, Wei Hu (Xavier) wrote:
> >>
> >> On 2019/1/26 5:50, Jason Gunthorpe wrote:
> >>> 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.
> >> Hi, Jason
> >>
> >> OK, I got your opinion and will modify it in v3 patch as below:
> >>
> >> end = msecs_to_jiffies(HNS_ROCE_V2_HW_RST_TIMEOUT) + jiffies;
> >> while (time_before(jiffies, end))
> >> if (!ops->get_hw_reset_stat(handle))
> >> break;
> > You shouldn't be looping like this at all, a busy loop is worse, don't
> > try and open code spinlocks.
> Hi, Jason
>
> OK, we will modify some places calling CMQ/mailbox operation,
> replace spinlock with mutex, and add msleep here:
>
> end = msecs_to_jiffies(HNS_ROCE_V2_HW_RST_TIMEOUT) + jiffies;
> while (time_before(jiffies, end)) {
> if (!ops->get_hw_reset_stat(handle))
> break;
> msleep(20);
> }
How many more times do I have to say not to code spin loops like
this???? Use proper locking!
Jason
