RE: [PATCH] lib: fix mempool name prefixes

> From: Anurag Mandal [mailto:[email protected]]
> Sent: Wednesday, 12 August 2026 13.03
> 
> The RIB library named the mempool holding its nodes "MP_<name>".
> That prefix is the one the mempool library itself prepends to
> the backing memzone, so the memzone ended up named
> "MP_MP_<name>" which is improper.
> 
> The FIB library passed its own name unchanged to the underlying
> RIB and did not add a prefix to the RIB name.
> 
> This patch makes name each object after its owner.
> The node mempool of a RIB is now "RIB_<name>" or "RIB6_<name>",
> and the RIB owned by a FIB is now "FIB_<name>" or "FIB6_<name>".
> 
> A mempool name is limited to RTE_MEMPOOL_NAMESIZE, which is much
> shorter than RTE_RIB_NAMESIZE.
> The name was passed down silently and an oversized one surfaced
> as an opaque rte_mempool_create() failure, so check the derived
> name up front and return ENAMETOOLONG instead. B
> ecause the prefixes now stack, a name is limited to 21 characters
> for a RIB, 20 for a RIB6, 17 for a FIB and 15 for a FIB6.
> Hence, shortening  the names used by the graph nodes, the l3fwd
> example and the unit tests accordingly.
> 
> Bugzilla ID: 1981 1982
> Fixes: 5a5793a5ffa2 ("rib: add RIB library")
> Fixes: f7e861e21c46 ("rib: support IPv6")
> Fixes: 39e927248416 ("fib: add FIB library")
> Fixes: 40d41a8a7b34 ("fib: support IPv6")

This patch reduces how long a FIB/RIB name can be, which is an API break.
I don't think it should be backported.

> 
> Signed-off-by: Anurag Mandal <[email protected]>
> ---

Some comments inline below.
With those comments addressed,
Acked-by: Morten Brørup <[email protected]>

[...]

> diff --git a/doc/guides/rel_notes/release_26_11.rst
> b/doc/guides/rel_notes/release_26_11.rst
> index c8cc86295d..043ce8fc2d 100644
> --- a/doc/guides/rel_notes/release_26_11.rst
> +++ b/doc/guides/rel_notes/release_26_11.rst
> @@ -93,6 +93,11 @@ API Changes
>     Also, make sure to start the actual text at the margin.
>     =======================================================
> 
> +* rib: The node mempool created by ``rte_rib_create()`` and
> ``rte_rib6_create()``
> +  is now named ``RIB_<name>`` and ``RIB6_<name>`` instead of
> ``MP_<name>``.
> +
> +* fib: The RIB created by ``rte_fib_create()`` and
> ``rte_fib6_create()``
> +  is now named ``FIB_<name>`` and ``FIB6_<name>``.

Please mention in the release notes how long the RIB, RIB6, FIB and FIB6 names are now allowed to be.

[...]

> diff --git a/lib/fib/rte_fib.c b/lib/fib/rte_fib.c
> index 184210f380..e032eca91d 100644
> --- a/lib/fib/rte_fib.c
> +++ b/lib/fib/rte_fib.c
> @@ -37,6 +37,9 @@ EAL_REGISTER_TAILQ(rte_fib_tailq)
>  #define FIB_RETURN_IF_TRUE(cond, retval)
>  #endif
> 
> +/* Prefix used for the memory objects owned by a FIB. */
> +#define FIB_MEM_PREFIX		"FIB_"
> +
>  struct rte_fib {
>  	char			name[RTE_FIB_NAMESIZE];
>  	enum rte_fib_type	type;	/**< Type of FIB struct */
> @@ -173,14 +176,16 @@ rte_fib_create(const char *name, int socket_id,
> struct rte_fib_conf *conf)
>  	rib_conf.ext_sz = conf->rib_ext_sz;
>  	rib_conf.max_nodes = conf->max_routes * 2;
> 
> -	rib = rte_rib_create(name, socket_id, &rib_conf);
> +	/* Add FIB Prefix to its mempool name */
> +	snprintf(mem_name, sizeof(mem_name), FIB_MEM_PREFIX "%s", name);

Please add check for snprintf() return value, to ensure mem_name has 0-termination at the end.
Something like (untested):

ret = snprintf(mem_name, sizeof(mem_name), FIB_MEM_PREFIX "%s", name);
if (unlikely(ret < 0 || ret >= sizeof(mem_name))) {
	rte_errno = ENAMETOOLONG;
	return NULL;
}

This check was already missing, so adding it is an improvement.

> +
> +	rib = rte_rib_create(mem_name, socket_id, &rib_conf);
>  	if (rib == NULL) {
>  		FIB_LOG(ERR,
> -			"Can not allocate RIB %s", name);
> +			"Can not allocate RIB %s", mem_name);
>  		return NULL;
>  	}
> 
> -	snprintf(mem_name, sizeof(mem_name), "FIB_%s", name);
>  	fib_list = RTE_TAILQ_CAST(rte_fib_tailq.head, rte_fib_list);
> 
>  	rte_mcfg_tailq_write_lock();
> diff --git a/lib/fib/rte_fib6.c b/lib/fib/rte_fib6.c
> index 770becdb61..dbe88fa25c 100644
> --- a/lib/fib/rte_fib6.c
> +++ b/lib/fib/rte_fib6.c
> @@ -37,6 +37,9 @@ EAL_REGISTER_TAILQ(rte_fib6_tailq)
>  #define FIB6_RETURN_IF_TRUE(cond, retval)
>  #endif
> 
> +/* Prefix used for the memory objects owned by a FIB6. */
> +#define FIB6_MEM_PREFIX		"FIB6_"
> +
>  struct rte_fib6 {
>  	char			name[RTE_FIB6_NAMESIZE];
>  	enum rte_fib6_type	type;	/**< Type of FIB struct */
> @@ -172,14 +175,16 @@ rte_fib6_create(const char *name, int socket_id,
> struct rte_fib6_conf *conf)
>  	rib_conf.ext_sz = conf->rib_ext_sz;
>  	rib_conf.max_nodes = conf->max_routes * 2;
> 
> -	rib = rte_rib6_create(name, socket_id, &rib_conf);
> +	/* Add FIB6 Prefix to its mempool name */
> +	snprintf(mem_name, sizeof(mem_name), FIB6_MEM_PREFIX "%s", name);

Also here:
Please add check for snprintf() return value, to ensure mem_name has 0-termination at the end.