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

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Message-ID: <20240708053850.GA6788@unreal>
Date: Mon, 8 Jul 2024 08:38:50 +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 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

> 
> 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
> >>
>