Re: [PATCH v3 0/8] nic: thunderx: fix communication races between VF & PF

[David Miller]

From: Vadim Lomovtsev <vlomovtsev@xxxxxxxxxxx>
Date: Wed, 20 Feb 2019 11:02:42 +0000

> The ThunderX CN88XX NIC Virtual Function driver uses mailbox interface
> to communicate to physical function driver. Each of VF has it's own pair
> of mailbox registers to read from and write to. The mailbox registers
> has no protection from possible races, so it has to be implemented
> at software side.
> 
> After long term testing by loop of 'ip link set <ifname> up/down'
> command it was found that there are two possible scenarios when
> race condition appears:
>  1. VF receives link change message from PF and VF send RX mode
> configuration message to PF in the same time from separate thread.
>  2. PF receives RX mode configuration from VF and in the same time,
> in separate thread PF detects link status change and sends appropriate
> message to particular VF.
> 
> Both cases leads to mailbox data to be rewritten, NIC VF messaging control
> data to be updated incorrectly and communication sequence gets broken.
> 
> This patch series is to address race condition with VF & PF communication.
> 
> Changes:
> v1 -> v2
>  - 0000: correct typo in cover letter subject: 'betwen' -> 'between';
>  - move link state polling request task from pf to vf 
>    instead of cheking status of mailbox irq;
> v2 -> v3
>  - 0003: change return type of nicvf_send_cfg_done() function
>    from int to void;
>  - 0007: update subject and remove unused variable 'netdev'
>    from nicvf_link_status_check_task() function;

Series applied, thanks.