NAK: [SRU][Yakkety][PATCH 1/1] net/mlx4_core: Avoid delays during VF driver device shutdown
Joshua R. Poulson
jrp at pun.org
Mon Apr 3 13:35:26 UTC 2017
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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