Re: [dpdk-dev] [PATCH v4 01/19] vhost: fix messages error checks

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 10/09/2018 10:03 AM, Tiwei Bie wrote:
> On Mon, Oct 08, 2018 at 05:25:39PM +0200, Maxime Coquelin wrote:
>> Return of message handling has now changed to an enum that can
>> take non-negative value that is not zero in case a reply is
>> needed. But the code checking the variable afterwards has not
>> been updated, leading to success messages handling being
>> treated as errors.
>>
>> Fixes: 2f270595c05d ("vhost: rework message handling as a callback array")
> 
> Fixline should be:
> Fixes: 0bff510b5ea6 ("vhost: unify message handling function signature")
> 
>>
>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>> Acked-by: Ilya Maximets <i.maximets@samsung.com>
>> ---
>>   lib/librte_vhost/vhost_user.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
>> index 7ef3fb4a4..060b41893 100644
>> --- a/lib/librte_vhost/vhost_user.c
>> +++ b/lib/librte_vhost/vhost_user.c
>> @@ -1783,7 +1783,7 @@ vhost_user_msg_handler(int vid, int fd)
>>   	}
>>   
>>   skip_to_post_handle:
>> -	if (!ret && dev->extern_ops.post_msg_handle) {
>> +	if (ret != VH_RESULT_ERR && dev->extern_ops.post_msg_handle) {
>>   		uint32_t need_reply;
>>   
>>   		ret = (*dev->extern_ops.post_msg_handle)(
>> @@ -1800,10 +1800,10 @@ vhost_user_msg_handler(int vid, int fd)
>>   		vhost_user_unlock_all_queue_pairs(dev);
>>   
>>   	if (msg.flags & VHOST_USER_NEED_REPLY) {
>> -		msg.payload.u64 = !!ret;
>> +		msg.payload.u64 = ret == VH_RESULT_ERR;
>>   		msg.size = sizeof(msg.payload.u64);
>>   		send_vhost_reply(fd, &msg);
>> -	} else if (ret) {
>> +	} else if (ret == VH_RESULT_ERR) {
>>   		RTE_LOG(ERR, VHOST_CONFIG,
>>   			"vhost message handling failed.\n");
>>   		return -1;
> 
> We also need to take care of the return value of .pre_msg_handle()
> and .post_msg_handle(). Otherwise, errors could be ignored.

Right. What I plan to do is setting ret to VH_RESULT_ERR if
pre/post_msg_handler() return is negative.

Does that sound reasonable to you?

I see that vhost-crypto does not respect the callbacks documentation wrt
to return value, and we might want to change the callbacks documentation
so that it returns an enum vh_result.

>> -- 
>> 2.17.1
>>