Re: [dpdk-stable] [PATCH v3] net/iavf: fix virtual channel return value error

[Ye Xiaolong <xiaolong.ye@intel.com>]

On 12/24, Zhang, Qi Z wrote:
>
>
>> -----Original Message-----
>> From: Cao, Yahui <yahui.cao@intel.com>
>> Sent: Tuesday, December 24, 2019 12:13 PM
>> To: Wu, Jingjing <jingjing.wu@intel.com>; Lu, Wenzhuo
>> <wenzhuo.lu@intel.com>
>> Cc: dev@dpdk.org; stable@dpdk.org; Zhang, Qi Z <qi.z.zhang@intel.com>; Cao,
>> Yahui <yahui.cao@intel.com>; Ye, Xiaolong <xiaolong.ye@intel.com>; Su,
>> Simei <simei.su@intel.com>
>> Subject: [PATCH v3] net/iavf: fix virtual channel return value error
>> 
>> In iavf_handle_virtchnl_msg(), it is not appropriate for _clear_cmd() to be used
>> as a notification to forground thread. So introduce
>> _notify_cmd() to fix this error. In addition, since _notify_cmd() contains
>> rte_wmb(), rte_compiler_barrier() is not necessary.
>> 
>> Sending msg from VF to PF is mainly by calling iavf_execute_vf_cmd(), the
>> whole virtchnl msg process is like,
>> 
>> iavf_execute_vf_cmd() will call iavf_aq_send_msg_to_pf() to send msg and
>> then polling the cmd done flag as "if (vf->pend_cmd ==
>> VIRTCHNL_OP_UNKNOWN)"
>> 
>> When reply msg is returned by pf, iavf_handle_virtchnl_msg() in isr will read
>> msg return value by "vf->cmd_retval = msg_ret" and immediately set the cmd
>> done flag by calling _clear_cmd() to notify the iavf_execute_vf_cmd().
>> 
>> iavf_execute_vf_cmd() find the cmd done flag is set and then check whether
>> command return value vf->cmd_retval is success or not.
>> 
>> However _clear_cmd() also resets the vf->cmd_retval to success, overwriting
>> the actual return value which is used for diagnosis.
>> So iavf_execute_vf_cmd() will always find vf->cmd_retval is success and then
>> return success.
>> 
>> Fixes: 22b123a36d07 ("net/avf: initialize PMD")
>> Cc: stable@dpdk.org
>> 
>> Signed-off-by: Yahui Cao <yahui.cao@intel.com>
>
>Acked-by: Qi Zhang <qi.z.zhang@intel.com>
>

Acked-by: Xiaolong Ye <xiaolong.ye@intel.com>

Applied to dpdk-next-net-intel, Thanks.