Re: mempool name size incorrect?

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed, 11 Mar 2026 10:52:11 +0000
Konstantin Ananyev <konstantin.ananyev@huawei.com> wrote:

> > > On 3/10/26 5:10 PM, Morten Brørup wrote:  
> > > > Isn't the RTE_MEMPOOL_NAMESIZE too short?
> > > >
> > > > Looking at the names sizes:
> > > >
> > > > RTE_MEMZONE_NAMESIZE = 32,
> > > > RTE_RING_NAMESIZE = RTE_MEMZONE_NAMESIZE - (sizeof("RG_")=4) + 1 =  
> > > 29,  
> > > > RTE_MEMPOOL_NAMESIZE = RTE_RING_NAMESIZE - (sizeof("MP_")=4) + 1 =  
> > 26  
> > > >
> > > > Referring to [1], I think it should be fixed as:
> > > > - #define RTE_MEMPOOL_NAMESIZE (RTE_RING_NAMESIZE - \
> > > > 			      sizeof(RTE_MEMPOOL_MZ_PREFIX) + 1)
> > > > + #define RTE_MEMPOOL_NAMESIZE (RTE_MEMZONE_NAMESIZE - \
> > > > 			      sizeof(RTE_MEMPOOL_MZ_PREFIX) + 1)
> > > >
> > > > There is no ring involved, so I guess it is some kind of copy-paste-  
> > > search-replace error.  
> > > >  
> > >
> > > I guess ring is involved in fact since the default mempool driver is
> > > ring.
> > >
> > > See drivers/mempool/ring/rte_mempool_ring.c ring_alloc().
> > >
> > > Yes, it is not ideal, but at least it explains why RTE_RING_NAMESIZE
> > > is used.  
> > 
> > Thanks, that explains it. Bad layer violation...
> > Let's hope no future mempool driver adds anything longer than "RG_" to the
> > name of any memzone it creates.
> > 
> > Looking into the associated string length checks, using a too long name will fail
> > with ENAMETOOLONG.
> > So, using a long mempool name might succeed with some mempool drivers and
> > fail with others. :-(
> > 
> > I guess there's no simple fix for that.
> > And I was wrong to think that the RTE_MEMPOOL_NAMESIZE should be
> > increased from 26 to 29.  
> 
> As a generic thought: might be it is time to make the length across these
> structs (mempool, ring, etc.) arbitrary?
> At our next big API breakage or so.

It would be good to switch to flexible array for these structures.
Put name[] at end of struct.

Might want to have a sanity check of really misuse like 1K or something