Re: [PATCH v8 29/30] packet: Refactor vhost-user memory region handling

[Laurent Vivier <lvivier@redhat.com>]

On 07/08/2025 08:10, David Gibson wrote:
>> @@ -437,12 +437,12 @@ static bool vu_set_mem_table_exec(struct vu_dev *vdev,
>>   			       r->size + r->mmap_offset);
>>   		}
>>   	}
>> -	vdev->nregions = memory->nregions;
>> +	vdev->memory.nregions = memory->nregions;
>>   
>>   	debug("vhost-user nregions: %u", memory->nregions);
>> -	for (i = 0; i < vdev->nregions; i++) {
>> +	for (i = 0; i < vdev->memory.nregions; i++) {
>>   		struct vhost_user_memory_region *msg_region = &memory->regions[i];
>> -		struct vu_dev_region *dev_region = &vdev->regions[i];
>> +		struct vu_dev_region *dev_region = &vdev->memory.regions[i];
>>   		void *mmap_addr;
>>   
>>   		debug("vhost-user region %d", i);
>> @@ -484,13 +484,7 @@ static bool vu_set_mem_table_exec(struct vu_dev *vdev,
>>   		}
>>   	}
>>   
>> -	/* As vu_packet_check_range() has no access to the number of
>> -	 * memory regions, mark the end of the array with mmap_addr = 0
>> -	 */
>> -	ASSERT(vdev->nregions < VHOST_USER_MAX_RAM_SLOTS - 1);
>> -	vdev->regions[vdev->nregions].mmap_addr = 0;
>> -
>> -	tap_sock_update_pool(vdev->regions, 0);
>> +	ASSERT(vdev->memory.nregions < VHOST_USER_MAX_RAM_SLOTS);
> It looks like the assertion is changing threshold by one, and I'm not
> sure why.

It's because previous version was using the last slot to mark the end of the array with a 
NULL memory region. Now, we have a counter, it's not needed anymore.

Thanks,
Laurent