Re: [dpdk-dev] [PATCH v2] net/failsafe: fix VLAN stripping configuration

[Thomas Monjalon <thomas@monjalon.net>]

02/11/2017 18:27, Ophir Munk:
> failsafe device has vlan stripping configured at startup however once
> a sub device is found as non-capable of vlan-stripping failsafe
> updates it configuration and removes vlan stripping from it.
> This update occurs only once at startup. Following a later plugin
> attempt and in case of vlan stripping mismatch between failsafe
> configuration and device capability - failsafe cannot recover and the
> device remains constantly in plug out state.
> 
> The sequence of events leading to this situation is described as
> follows:
> 1. Start testpmd with failsafe where mlx4 is a sub device (not capable
> of vlan stripping). Expected printout:
> PMD: net_failsafe: Disabling VLAN stripping offload
> 2. Execute:
> testpmd> port stop all
> testpmd> port config all max-pkt-len 2048
> testpmd> port start all
> 3. Do a plug out (e.g. disable sriov)
> 4. Do a plug in (e.g. enable sriov)
> 5. Expected result: failsafe successfully configures and starts its sub
> devices
> Actual result: failsafe is continuously failing with these messages:
> PMD: net_failsafe: VLAN stripping offload requested but not supported by
> sub_device 0
> PMD: net_failsafe: device already configured, cannot fix live
> configuration
> PMD: net_failsafe: Unable to synchronize sub device state
> 
> Root cause analysis: at startup failsafe removes vlan stripping from its
> configuration. After executing "port config all max-pkt-len 2048"
> testpmd marks failsafe in need for configuration update.
> After executing "port start all" testpmd overrides failsafe
> configuration with its own configuration which includes vlan stripping
> 
> During the plugin attempt failsafe refuses to update its configuration
> by removing vlan stripping since it has already updated its
> configuration at startup.
> 
> The fix is for failsafe to stop validation and disabling non-supported
> offloads in its sub-devices.
> 
> Cc: stable@dpdk.org
> Fixes: bbc6a53dda44 ("net/failsafe: support Rx offload capabilities")

The Cc:stable line is usually below the Fixes: line.

> Signed-off-by: Ophir Munk <ophirmu@mellanox.com>

The fix in this v2 matches what Gaetan requested after v1.

I agree it is better that failsafe does not interfere in configurations.
The responsibility of failsafe is to build the capability set.
The responsibility of the application is to check the capabilities
before configuring the failsafe device (like any other device).

Acked-by: Thomas Monjalon <thomas@monjalon.net>