RE: [PATCH] mbuf: de-inline sanity checking a reinitialized mbuf

[Ivan Malov <ivan.malov@arknetworks.am>]

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On Sun, 20 Jul 2025, Morten Brørup wrote:

>> From: Ivan Malov [mailto:ivan.malov@arknetworks.am]
>> Sent: Sunday, 20 July 2025 00.30
>>
>> Hi Morten,
>>
>> On Sat, 19 Jul 2025, Morten Brørup wrote:
>>
>>>> From: Morten Brørup [mailto:mb@smartsharesystems.com]
>>>> Sent: Saturday, 19 July 2025 12.23
>>>>
>>>> Sanity checking a reinitialized mbuf (a.k.a. raw mbuf) has been
>>>> refactored
>>>> to follow the same design pattern as sanity checking a normal mbuf,
>> and
>>>> now depends on RTE_LIBRTE_MBUF_DEBUG instead of RTE_ENABLE_ASSERT.
>>>>
>>>> The details of the changes are as follows:
>>>>
>>>> Non-inlined functions rte_mbuf_raw_sanity_check() and
>>>> rte_mbuf_raw_check()
>>>> have been added.
>>>> They do for a reinitialized mbuf what rte_mbuf_sanity_check() and
>>>> rte_mbuf_check() do for a normal mbuf.
>>>> They basically check the same conditions as
>>>> __rte_mbuf_raw_sanity_check()
>>>> previously did, but use "if (!condition) rte_panic(message)" instead
>> of
>>>> RTE_ASSSERT(), so they don't depend on RTE_ENABLE_ASSERT.
>>>>
>>>> The inline function __rte_mbuf_raw_sanity_check() has been replaced
>>>> by the new macro __rte_mbuf_raw_sanity_check_mp(), which either calls
>>>> rte_mbuf_raw_sanity_check() or does nothing, depending on
>>>> RTE_LIBRTE_MBUF_DEBUG, just like the __rte_mbuf_sanity_check() macro
>>>> does
>>>> for a normal mbuf.
>>>>
>>>> Note that the new macro __rte_mbuf_raw_sanity_check_mp() takes an
>>>> optional
>>>> mempool parameter to verify that the mbuf belongs to the expected
>> mbuf
>>>> pool.
>>>> This addition is mainly relevant for sanity checking reinitialized
>> mbufs
>>>> freed directly into a given mempool by a PMD when using
>>>> RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE.
>>>>
>>>> The macro __rte_mbuf_raw_sanity_check() has been kept for backwards
>> API
>>>> compatibility.
>>>> It simply calls __rte_mbuf_raw_sanity_check_mp() without specifying a
>>>> mempool.
>>>>
>>>> Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
>>>
>>> Building this with RTE_LIBRTE_MBUF_DEBUG 1 in rte_config.h spews out
>> warnings like:
>>
>> Oddly, for me, building DPDK this way does not result in similar
>> warnings.
>> OS: Debian 12, gcc (Debian 12.2.0-14) 12.2.0, meson 1.0.1, ninja 1.11.1.
>>
>> May be I'm missing something.
>
> Build commands:
> meson setup -Dplatform=generic -Dmax_numa_nodes=1 -Dcheck_includes=true build

Thanks, with 'check_includes=true', the warnings show up indeed.

Forgive me being unoriginal, but, given the fact the whole RTE_LIBRTE_MBUF_DEBUG
section in 'rte_mbuf.h' is based on the two new experimental APIs, how about
adding a check to the '#ifdef RTE_LIBRTE_MBUF_DEBUG' part, something like

#ifndef ALLOW_EXPERIMENTAL_API
#error "For RTE_LIBRTE_MBUF_DEBUG, one shall also enable ALLOW_EXPERIMENTAL_API"
#endif

or an equivalent check expressed in meson + a reminder to remove when stable?

For me, with ALLOW_EXPERIMENTAL_API defined alongside RTE_LIBRTE_MBUF_DEBUG,
the code builds seemingly without warnings.

Thank you.

> ninja -C build
>
> OS: Ubuntu 24.04.2 LTS (GNU/Linux 6.8.0-60-generic x86_64), gcc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0, meson 1.3.2, ninja 1.11.1.
>
> diff --git a/config/rte_config.h b/config/rte_config.h
> index 05344e2619..f1ad7f09de 100644
> --- a/config/rte_config.h
> +++ b/config/rte_config.h
> @@ -64,6 +64,7 @@
>
> /* mbuf defines */
> #define RTE_MBUF_DEFAULT_MEMPOOL_OPS "ring_mp_mc"
> +#define RTE_LIBRTE_MBUF_DEBUG 1 /* default not set */
>
> /* ether defines */
> #define RTE_MAX_QUEUES_PER_PORT 1024
>
>>
>> Thank you.
>>
>>>
>>> ../lib/mbuf/rte_mbuf.h: In function ‘rte_mbuf_raw_free’:
>>> ../lib/mbuf/rte_mbuf.h:700:9: warning: ‘rte_mbuf_raw_sanity_check’ is
>> deprecated: Symbol is not yet part of stable ABI [-Wdeprecated-
>> declarations]
>>>  700 |         __rte_mbuf_raw_sanity_check_mp(m, NULL);
>>>      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> ../lib/mbuf/rte_mbuf.h:542:1: note: declared here
>>>  542 | rte_mbuf_raw_sanity_check(const struct rte_mbuf *m, const
>> struct rte_mempool *mp);
>>>      | ^~~~~~~~~~~~~~~~~~~~~~~~~
>>>
>>> Exporting the new APIs as non-experimental (i.e. using
>> RTE_EXPORT_SYMBOL() instead of RTE_EXPORT_EXPERIMENTAL_SYMBOL() in the C
>> file, and omitting __rte_experimental in the header file, as shown
>> below) works, but is that acceptable?
>>>
>>> Or is there a better way of avoiding these warnings?
>>>
>>>> ---
>>>>  lib/mbuf/rte_mbuf.c |  61 ++++++++++++++++++++++++++
>>>>  lib/mbuf/rte_mbuf.h | 104 ++++++++++++++++++++++++++++--------------
>> --
>>>>  2 files changed, 127 insertions(+), 38 deletions(-)
>>>>
>>>> diff --git a/lib/mbuf/rte_mbuf.c b/lib/mbuf/rte_mbuf.c
>>>> index 9e7731a8a2..ff4db73b50 100644
>>>> --- a/lib/mbuf/rte_mbuf.c
>>>> +++ b/lib/mbuf/rte_mbuf.c
>>>> @@ -373,6 +373,67 @@ rte_pktmbuf_pool_create_extbuf(const char *name,
>>>> unsigned int n,
>>>>  	return mp;
>>>>  }
>>>>
>>>> +/* do some sanity checks on a reinitialized mbuf: panic if it fails
>> */
>>>> +RTE_EXPORT_EXPERIMENTAL_SYMBOL(rte_mbuf_raw_sanity_check, 25.11)
>>>
>>> +// RTE_EXPORT_EXPERIMENTAL_SYMBOL(rte_mbuf_raw_sanity_check, 25.11)
>>> +RTE_EXPORT_SYMBOL(rte_mbuf_raw_sanity_check)
>>>
>>>> +void
>>>> +rte_mbuf_raw_sanity_check(const struct rte_mbuf *m, const struct
>>>> rte_mempool *mp)
>>>> +{
>>>> +	const char *reason;
>>>> +
>>>> +	if (rte_mbuf_raw_check(m, mp, &reason))
>>>> +		rte_panic("%s\n", reason);
>>>> +}
>>>> +
>>>> +RTE_EXPORT_EXPERIMENTAL_SYMBOL(rte_mbuf_raw_check, 25.11)
>>>
>>> +// RTE_EXPORT_EXPERIMENTAL_SYMBOL(rte_mbuf_raw_check, 25.11)
>>> +RTE_EXPORT_SYMBOL(rte_mbuf_raw_check)
>>>
>>>> +int rte_mbuf_raw_check(const struct rte_mbuf *m, const struct
>>>> rte_mempool *mp,
>>>> +		   const char **reason)
>>>> +{
>>>> +	/* check sanity */
>>>> +	if (rte_mbuf_check(m, 0, reason) == -1)
>>>> +		return -1;
>>>> +
>>>> +	/* check initialized */
>>>> +	if (rte_mbuf_refcnt_read(m) != 1) {
>>>> +		*reason = "uninitialized ref cnt";
>>>> +		return -1;
>>>> +	}
>>>> +	if (m->next != NULL) {
>>>> +		*reason = "uninitialized next ptr";
>>>> +		return -1;
>>>> +	}
>>>> +	if (m->nb_segs != 1) {
>>>> +		*reason = "uninitialized nb_segs";
>>>> +		return -1;
>>>> +	}
>>>> +	if (RTE_MBUF_CLONED(m)) {
>>>> +		*reason = "cloned";
>>>> +		return -1;
>>>> +	}
>>>> +	if (RTE_MBUF_HAS_EXTBUF(m)) {
>>>> +		if (!RTE_MBUF_HAS_PINNED_EXTBUF(m)) {
>>>> +			*reason = "external buffer not pinned";
>>>> +			return -1;
>>>> +		}
>>>> +
>>>> +		uint16_t cnt = rte_mbuf_ext_refcnt_read(m->shinfo);
>>>> +		if ((cnt == 0) || (cnt == UINT16_MAX)) {
>>>> +			*reason = "pinned external buffer bad ref cnt";
>>>> +			return -1;
>>>> +		}
>>>> +		if (cnt != 1) {
>>>> +			*reason = "pinned external buffer uninitialized ref
>>>> cnt";
>>>> +			return -1;
>>>> +		}
>>>> +	}
>>>> +
>>>> +	if (mp != NULL && m->pool != mp) {
>>>> +		*reason = "wrong mbuf pool";
>>>> +		return -1;
>>>> +	}
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>>  /* do some sanity checks on a mbuf: panic if it fails */
>>>>  RTE_EXPORT_SYMBOL(rte_mbuf_sanity_check)
>>>>  void
>>>> diff --git a/lib/mbuf/rte_mbuf.h b/lib/mbuf/rte_mbuf.h
>>>> index 06ab7502a5..2621cc385c 100644
>>>> --- a/lib/mbuf/rte_mbuf.h
>>>> +++ b/lib/mbuf/rte_mbuf.h
>>>> @@ -339,11 +339,17 @@ rte_pktmbuf_priv_flags(struct rte_mempool *mp)
>>>>
>>>>  #ifdef RTE_LIBRTE_MBUF_DEBUG
>>>>
>>>> +/**  check reinitialized mbuf type in debug mode */
>>>> +#define __rte_mbuf_raw_sanity_check_mp(m, mp)
>>>> rte_mbuf_raw_sanity_check(m, mp)
>>>> +
>>>>  /**  check mbuf type in debug mode */
>>>>  #define __rte_mbuf_sanity_check(m, is_h) rte_mbuf_sanity_check(m,
>> is_h)
>>>>
>>>>  #else /*  RTE_LIBRTE_MBUF_DEBUG */
>>>>
>>>> +/**  check reinitialized mbuf type in debug mode */
>>>> +#define __rte_mbuf_raw_sanity_check_mp(m, mp) do { } while (0)
>>>> +
>>>>  /**  check mbuf type in debug mode */
>>>>  #define __rte_mbuf_sanity_check(m, is_h) do { } while (0)
>>>>
>>>> @@ -513,6 +519,54 @@ rte_mbuf_ext_refcnt_update(struct
>>>> rte_mbuf_ext_shared_info *shinfo,
>>>>  } while (0)
>>>>
>>>>
>>>> +/**
>>>> + * @warning
>>>> + * @b EXPERIMENTAL: This API may change, or be removed, without
>> prior
>>>> notice.
>>>> + *
>>>> + * Sanity checks on a reinitialized mbuf.
>>>> + *
>>>> + * Check the consistency of the given reinitialized mbuf.
>>>> + * The function will cause a panic if corruption is detected.
>>>> + *
>>>> + * Check that the mbuf is properly reinitialized (refcnt=1,
>> next=NULL,
>>>> + * nb_segs=1), as done by rte_pktmbuf_prefree_seg().
>>>> + *
>>>> + * @param m
>>>> + *   The mbuf to be checked.
>>>> + * @param mp
>>>> + *   The mempool to which the mbuf belongs.
>>>> + *   NULL if unknown, not to be checked.
>>>> + */
>>>> +__rte_experimental
>>>
>>> +// __rte_experimental
>>>
>>>> +void
>>>> +rte_mbuf_raw_sanity_check(const struct rte_mbuf *m, const struct
>>>> rte_mempool *mp);
>>>> +
>>>> +/**
>>>> + * @warning
>>>> + * @b EXPERIMENTAL: This API may change, or be removed, without
>> prior
>>>> notice.
>>>> + *
>>>> + * Sanity checks on a reinitialized mbuf.
>>>> + *
>>>> + * Almost like rte_mbuf_raw_sanity_check(), but this function gives
>> the
>>>> reason
>>>> + * if corruption is detected rather than panic.
>>>> + *
>>>> + * @param m
>>>> + *   The mbuf to be checked.
>>>> + * @param mp
>>>> + *   The mempool to which the mbuf belongs.
>>>> + *   NULL if unknown, not to be checked.
>>>> + * @param reason
>>>> + *   A reference to a string pointer where to store the reason why a
>>>> mbuf is
>>>> + *   considered invalid.
>>>> + * @return
>>>> + *   - 0 if no issue has been found, reason is left untouched.
>>>> + *   - -1 if a problem is detected, reason then points to a string
>>>> describing
>>>> + *     the reason why the mbuf is deemed invalid.
>>>> + */
>>>> +__rte_experimental
>>>
>>> +// __rte_experimental
>>>
>>>> +int rte_mbuf_raw_check(const struct rte_mbuf *m, const struct
>>>> rte_mempool *mp,
>>>> +		   const char **reason);
>>>> +
>>>>  /**
>>>>   * Sanity checks on an mbuf.
>>>>   *
>>>> @@ -550,33 +604,11 @@ rte_mbuf_sanity_check(const struct rte_mbuf *m,
>>>> int is_header);
>>>>  int rte_mbuf_check(const struct rte_mbuf *m, int is_header,
>>>>  		   const char **reason);
>>>>
>>>> -/**
>>>> - * Sanity checks on a reinitialized mbuf in debug mode.
>>>> - *
>>>> - * Check the consistency of the given reinitialized mbuf.
>>>> - * The function will cause a panic if corruption is detected.
>>>> - *
>>>> - * Check that the mbuf is properly reinitialized (refcnt=1,
>> next=NULL,
>>>> - * nb_segs=1), as done by rte_pktmbuf_prefree_seg().
>>>> - *
>>>> - * @param m
>>>> - *   The mbuf to be checked.
>>>> - */
>>>> -static __rte_always_inline void
>>>> -__rte_mbuf_raw_sanity_check(__rte_unused const struct rte_mbuf *m)
>>>> -{
>>>> -	RTE_ASSERT(rte_mbuf_refcnt_read(m) == 1);
>>>> -	RTE_ASSERT(m->next == NULL);
>>>> -	RTE_ASSERT(m->nb_segs == 1);
>>>> -	RTE_ASSERT(!RTE_MBUF_CLONED(m));
>>>> -	RTE_ASSERT(!RTE_MBUF_HAS_EXTBUF(m) ||
>>>> -			(RTE_MBUF_HAS_PINNED_EXTBUF(m) &&
>>>> -			rte_mbuf_ext_refcnt_read(m->shinfo) == 1));
>>>> -	__rte_mbuf_sanity_check(m, 0);
>>>> -}
>>>> +/** For backwards compatibility. */
>>>> +#define __rte_mbuf_raw_sanity_check(m)
>>>> __rte_mbuf_raw_sanity_check_mp(m, NULL)
>>>>
>>>>  /** For backwards compatibility. */
>>>> -#define MBUF_RAW_ALLOC_CHECK(m) __rte_mbuf_raw_sanity_check(m)
>>>> +#define MBUF_RAW_ALLOC_CHECK(m) __rte_mbuf_raw_sanity_check_mp(m,
>> NULL)
>>>>
>>>>  /**
>>>>   * Allocate an uninitialized mbuf from mempool *mp*.
>>>> @@ -606,7 +638,7 @@ static inline struct rte_mbuf
>>>> *rte_mbuf_raw_alloc(struct rte_mempool *mp)
>>>>
>>>>  	if (rte_mempool_get(mp, &ret.ptr) < 0)
>>>>  		return NULL;
>>>> -	__rte_mbuf_raw_sanity_check(ret.m);
>>>> +	__rte_mbuf_raw_sanity_check_mp(ret.m, mp);
>>>>  	return ret.m;
>>>>  }
>>>>
>>>> @@ -644,7 +676,7 @@ rte_mbuf_raw_alloc_bulk(struct rte_mempool *mp,
>>>> struct rte_mbuf **mbufs, unsigne
>>>>  	int rc = rte_mempool_get_bulk(mp, (void **)mbufs, count);
>>>>  	if (likely(rc == 0))
>>>>  		for (unsigned int idx = 0; idx < count; idx++)
>>>> -			__rte_mbuf_raw_sanity_check(mbufs[idx]);
>>>> +			__rte_mbuf_raw_sanity_check_mp(mbufs[idx], mp);
>>>>  	return rc;
>>>>  }
>>>>
>>>> @@ -665,7 +697,7 @@ rte_mbuf_raw_alloc_bulk(struct rte_mempool *mp,
>>>> struct rte_mbuf **mbufs, unsigne
>>>>  static __rte_always_inline void
>>>>  rte_mbuf_raw_free(struct rte_mbuf *m)
>>>>  {
>>>> -	__rte_mbuf_raw_sanity_check(m);
>>>> +	__rte_mbuf_raw_sanity_check_mp(m, NULL);
>>>>  	rte_mempool_put(m->pool, m);
>>>>  }
>>>>
>>>> @@ -696,12 +728,8 @@ __rte_experimental
>>>>  static __rte_always_inline void
>>>>  rte_mbuf_raw_free_bulk(struct rte_mempool *mp, struct rte_mbuf
>> **mbufs,
>>>> unsigned int count)
>>>>  {
>>>> -	for (unsigned int idx = 0; idx < count; idx++) {
>>>> -		const struct rte_mbuf *m = mbufs[idx];
>>>> -		RTE_ASSERT(m != NULL);
>>>> -		RTE_ASSERT(m->pool == mp);
>>>> -		__rte_mbuf_raw_sanity_check(m);
>>>> -	}
>>>> +	for (unsigned int idx = 0; idx < count; idx++)
>>>> +		__rte_mbuf_raw_sanity_check_mp(mbufs[idx], mp);
>>>>
>>>>  	rte_mempool_put_bulk(mp, (void **)mbufs, count);
>>>>  }
>>>> @@ -1021,22 +1049,22 @@ static inline int
>> rte_pktmbuf_alloc_bulk(struct
>>>> rte_mempool *pool,
>>>>  	switch (count % 4) {
>>>>  	case 0:
>>>>  		while (idx != count) {
>>>> -			__rte_mbuf_raw_sanity_check(mbufs[idx]);
>>>> +			__rte_mbuf_raw_sanity_check_mp(mbufs[idx], pool);
>>>>  			rte_pktmbuf_reset(mbufs[idx]);
>>>>  			idx++;
>>>>  			/* fall-through */
>>>>  	case 3:
>>>> -			__rte_mbuf_raw_sanity_check(mbufs[idx]);
>>>> +			__rte_mbuf_raw_sanity_check_mp(mbufs[idx], pool);
>>>>  			rte_pktmbuf_reset(mbufs[idx]);
>>>>  			idx++;
>>>>  			/* fall-through */
>>>>  	case 2:
>>>> -			__rte_mbuf_raw_sanity_check(mbufs[idx]);
>>>> +			__rte_mbuf_raw_sanity_check_mp(mbufs[idx], pool);
>>>>  			rte_pktmbuf_reset(mbufs[idx]);
>>>>  			idx++;
>>>>  			/* fall-through */
>>>>  	case 1:
>>>> -			__rte_mbuf_raw_sanity_check(mbufs[idx]);
>>>> +			__rte_mbuf_raw_sanity_check_mp(mbufs[idx], pool);
>>>>  			rte_pktmbuf_reset(mbufs[idx]);
>>>>  			idx++;
>>>>  			/* fall-through */
>>>> --
>>>> 2.43.0
>>>
>>>
>