NAK: [SRU][Yakkety][PATCH 1/1] net/mlx4_core: Avoid delays during VF driver device shutdown
Joseph Salisbury
joseph.salisbury at canonical.com
Mon Apr 3 14:15:20 UTC 2017
Thanks, Josh. An explanation of the new test kernel and a link can be
found here:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1672785/comments/7
On 04/03/2017 03:03 PM, Joshua R. Poulson wrote:
> I'll test it as soon as I see it, thanks! --jrp
>
> On Mon, Apr 3, 2017 at 6:45 AM, Joseph Salisbury
> <joseph.salisbury at canonical.com> wrote:
>> I have a Yakkety test kernel now available that included commit
>> b4353708f5a1c084fd73f1b6fd243b142157b173 and commit
>> 4cbe4dac82e423ecc9a0ba46af24a860853259f4. Having commit b4353708f5a1c0
>> removes MLX4_INTERFACE_STATE_SHUTDOWN and all references to it. It
>> allows commit 4cbe4dac82e423ecc9a0ba46af24a860853259f4 to pick cleanly
>> and not require a backport.
>>
>> Xenial did not require b4353708f5a(It reverts commit 9d769311805 which
>> was added in v4.7-rc6) and it was a clean pick in Xenial. Zesty already
>> has commit b4353708f5a. I think both commits should be added to
>> Yakkety, not just 4cbe4dac82e4.
>>
>> I'll post a link to the v2 test kernel in the bug and resubmit a v2 SRU
>> once everyone agrees thats the way to go.
>>
>> Thanks,
>>
>> Joe
>>
>>
>>
>> On 04/03/2017 02:35 PM, Joshua R. Poulson wrote:
>>> Our friends at Mellanox have, we have been testing VF remove and add
>>> as part of SR-IOV in Azure testing. Our regression tests include
>>> on-premises Hyper-V as well.
>>>
>>> Thanks --jrp
>>>
>>> On Mon, Apr 3, 2017 at 6:32 AM, Thadeu Lima de Souza Cascardo
>>> <cascardo at canonical.com> wrote:
>>>> On Mon, Apr 03, 2017 at 05:11:34AM -0700, Joshua R. Poulson wrote:
>>>>> We're engaged to test the driver in the intended scenario and code
>>>>> path. We have a stable repro for the bug that this fixes.
>>>>>
>>>>> Thanks, --jrp
>>>>>
>>>> Is that on Yakkety, with this Yakkety backport as is?
>>>>
>>>> I am more concerned about the paths that would use SHUTDOWN, have you tested
>>>> these as well?
>>>>
>>>> Thanks.
>>>> Cascardo.
>>>>
>>>>> On Mon, Apr 3, 2017 at 2:26 AM, Thadeu Lima de Souza Cascardo
>>>>> <cascardo at canonical.com> wrote:
>>>>>> On Thu, Mar 30, 2017 at 04:35:59PM -0400, Joseph Salisbury wrote:
>>>>>>> From: Jack Morgenstein <jackm at dev.mellanox.co.il>
>>>>>>>
>>>>>>> BugLink: http://bugs.launchpad.net/bugs/1672785
>>>>>>>
>>>>>>> Some Hypervisors detach VFs from VMs by instantly causing an FLR event
>>>>>>> to be generated for a VF.
>>>>>>>
>>>>>>> In the mlx4 case, this will cause that VF's comm channel to be disabled
>>>>>>> before the VM has an opportunity to invoke the VF device's "shutdown"
>>>>>>> method.
>>>>>>>
>>>>>>> For such Hypervisors, there is a race condition between the VF's
>>>>>>> shutdown method and its internal-error detection/reset thread.
>>>>>>>
>>>>>>> The internal-error detection/reset thread (which runs every 5 seconds) also
>>>>>>> detects a disabled comm channel. If the internal-error detection/reset
>>>>>>> flow wins the race, we still get delays (while that flow tries repeatedly
>>>>>>> to detect comm-channel recovery).
>>>>>>>
>>>>>>> The cited commit fixed the command timeout problem when the
>>>>>>> internal-error detection/reset flow loses the race.
>>>>>>>
>>>>>>> This commit avoids the unneeded delays when the internal-error
>>>>>>> detection/reset flow wins.
>>>>>>>
>>>>>>> Fixes: d585df1c5ccf ("net/mlx4_core: Avoid command timeouts during VF driver device shutdown")
>>>>>>> Signed-off-by: Jack Morgenstein <jackm at dev.mellanox.co.il>
>>>>>>> Reported-by: Simon Xiao <sixiao at microsoft.com>
>>>>>>> Signed-off-by: Tariq Toukan <tariqt at mellanox.com>
>>>>>>> Signed-off-by: David S. Miller <davem at davemloft.net>
>>>>>>> (backported from commit 4cbe4dac82e423ecc9a0ba46af24a860853259f4)
>>>>>>> Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
>>>>>>> ---
>>>>>>> drivers/net/ethernet/mellanox/mlx4/cmd.c | 11 +++++++++++
>>>>>>> drivers/net/ethernet/mellanox/mlx4/main.c | 11 +++++++++++
>>>>>>> include/linux/mlx4/device.h | 1 +
>>>>>>> 3 files changed, 23 insertions(+)
>>>>>>>
>>>>>>> diff --git a/drivers/net/ethernet/mellanox/mlx4/cmd.c b/drivers/net/ethernet/mellanox/mlx4/cmd.c
>>>>>>> index f04a423..be6906b 100644
>>>>>>> --- a/drivers/net/ethernet/mellanox/mlx4/cmd.c
>>>>>>> +++ b/drivers/net/ethernet/mellanox/mlx4/cmd.c
>>>>>>> @@ -2278,6 +2278,17 @@ static int sync_toggles(struct mlx4_dev *dev)
>>>>>>> rd_toggle = swab32(readl(&priv->mfunc.comm->slave_read));
>>>>>>> if (wr_toggle == 0xffffffff || rd_toggle == 0xffffffff) {
>>>>>>> /* PCI might be offline */
>>>>>>> +
>>>>>>> + /* If device removal has been requested,
>>>>>>> + * do not continue retrying.
>>>>>>> + */
>>>>>>> + if (dev->persist->interface_state &
>>>>>>> + MLX4_INTERFACE_STATE_NOWAIT) {
>>>>>>> + mlx4_warn(dev,
>>>>>>> + "communication channel is offline\n");
>>>>>>> + return -EIO;
>>>>>>> + }
>>>>>>> +
>>>>>>> msleep(100);
>>>>>>> wr_toggle = swab32(readl(&priv->mfunc.comm->
>>>>>>> slave_write));
>>>>>>> diff --git a/drivers/net/ethernet/mellanox/mlx4/main.c b/drivers/net/ethernet/mellanox/mlx4/main.c
>>>>>>> index 7183ac4..ea5e362 100644
>>>>>>> --- a/drivers/net/ethernet/mellanox/mlx4/main.c
>>>>>>> +++ b/drivers/net/ethernet/mellanox/mlx4/main.c
>>>>>>> @@ -1916,6 +1916,14 @@ static int mlx4_comm_check_offline(struct mlx4_dev *dev)
>>>>>>> (u32)(1 << COMM_CHAN_OFFLINE_OFFSET));
>>>>>>> if (!offline_bit)
>>>>>>> return 0;
>>>>>>> +
>>>>>>> + /* If device removal has been requested,
>>>>>>> + * do not continue retrying.
>>>>>>> + */
>>>>>>> + if (dev->persist->interface_state &
>>>>>>> + MLX4_INTERFACE_STATE_NOWAIT)
>>>>>>> + break;
>>>>>>> +
>>>>>>> /* There are cases as part of AER/Reset flow that PF needs
>>>>>>> * around 100 msec to load. We therefore sleep for 100 msec
>>>>>>> * to allow other tasks to make use of that CPU during this
>>>>>>> @@ -3930,6 +3938,9 @@ static void mlx4_remove_one(struct pci_dev *pdev)
>>>>>>> struct devlink *devlink = priv_to_devlink(priv);
>>>>>>> int active_vfs = 0;
>>>>>>>
>>>>>>> + if (mlx4_is_slave(dev))
>>>>>>> + persist->interface_state |= MLX4_INTERFACE_STATE_NOWAIT;
>>>>>>> +
>>>>>>> mutex_lock(&persist->interface_state_mutex);
>>>>>>> persist->interface_state |= MLX4_INTERFACE_STATE_DELETION;
>>>>>>> mutex_unlock(&persist->interface_state_mutex);
>>>>>>> diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h
>>>>>>> index 42da355..d49f11d 100644
>>>>>>> --- a/include/linux/mlx4/device.h
>>>>>>> +++ b/include/linux/mlx4/device.h
>>>>>>> @@ -468,6 +468,7 @@ enum {
>>>>>>> MLX4_INTERFACE_STATE_UP = 1 << 0,
>>>>>>> MLX4_INTERFACE_STATE_DELETION = 1 << 1,
>>>>>>> MLX4_INTERFACE_STATE_SHUTDOWN = 1 << 2,
>>>>>>> + MLX4_INTERFACE_STATE_NOWAIT = 1 << 2,
>>>>>> So, NOWAIT and SHUTDOWN are defined to the same value, so it might be
>>>>>> necessary to review it that is going to work as expected. Maybe doing
>>>>>> the shutdown removal is a path to consider (commit
>>>>>> b4353708f5a1c084fd73f1b6fd243b142157b173).
>>>>>>
>>>>>> Cascardo.
>>>>>>
>>>>>>> };
>>>>>>>
>>>>>>> #define MSTR_SM_CHANGE_MASK (MLX4_EQ_PORT_INFO_MSTR_SM_SL_CHANGE_MASK | \
>>>>>>> --
>>>>>>> 2.7.4
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> kernel-team mailing list
>>>>>>> kernel-team at lists.ubuntu.com
>>>>>>> https://lists.ubuntu.com/mailman/listinfo/kernel-team
>>>>>> --
>>>>>> kernel-team mailing list
>>>>>> kernel-team at lists.ubuntu.com
>>>>>> https://lists.ubuntu.com/mailman/listinfo/kernel-team
>>
>>
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