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 13:45:59 UTC 2017
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
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