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

[David Gibson <david@gibson.dropbear.id.au>]

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On Thu, Aug 07, 2025 at 11:05:46AM +0200, Laurent Vivier wrote:
> 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.

Ah, ok.  Might be worth mentioning that in the commit message.

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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