[dpdk-dev] [PATCH v3] mempool: return 0 if area is too small on populate

[Ray Kinsella]

On 25/04/2020 23:23, Thomas Monjalon wrote:
> From: Olivier Matz <olivier.matz at 6wind.com>
> 
> Change rte_mempool_populate_iova() and rte_mempool_populate_iova() to
> return 0 instead of -EINVAL when there is not enough room to store one
> object, as it can be helpful for applications to distinguish this
> specific case.
> 
> As this is an ABI change, use symbol versioning to preserve old
> behavior for binary applications.
> 
> Signed-off-by: Olivier Matz <olivier.matz at 6wind.com>
> ---
> 
> changes in v3:
>     - rebase
>     - remove deprecation notice
>     - notify API change in release notes
>     - fix ABI version from 20.0.1 to 20.0.2 (should be 21 maybe)

yes, should be v21.

> 
> This v3 cannot be merged because of a false positive ABI check:
> 
> 2 Removed functions:
>   'function int rte_mempool_populate_iova(rte_mempool*, char*, rte_iova_t, size_t, rte_mempool_memchunk_free_cb_t*, void*)'    {rte_mempool_populate_iova@@DPDK_20.0}
>   'function int rte_mempool_populate_virt(rte_mempool*, char*, size_t, size_t, rte_mempool_memchunk_free_cb_t*, void*)'    {rte_mempool_populate_virt@@DPDK_20.0}

Well it's not really a false positive, as the v20 symbols are now missing.
See notes on VERSION_SYMBOL.

> 
> ---
>  doc/guides/rel_notes/deprecation.rst       |  5 --
>  doc/guides/rel_notes/release_20_05.rst     |  4 ++
>  examples/ntb/ntb_fwd.c                     |  2 +-
>  lib/librte_mempool/meson.build             |  2 +
>  lib/librte_mempool/rte_mempool.c           | 77 ++++++++++++++++++----
>  lib/librte_mempool/rte_mempool.h           | 14 ++--
>  lib/librte_mempool/rte_mempool_version.map |  7 ++
>  7 files changed, 90 insertions(+), 21 deletions(-)
> 
> diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
> index 1339f54f5f..20aa745b77 100644
> --- a/doc/guides/rel_notes/deprecation.rst
> +++ b/doc/guides/rel_notes/deprecation.rst
> @@ -65,11 +65,6 @@ Deprecation Notices
>    structure would be made internal (or removed if all dependencies are cleared)
>    in future releases.
>  
> -* mempool: starting from v20.05, the API of rte_mempool_populate_iova()
> -  and rte_mempool_populate_virt() will change to return 0 instead
> -  of -EINVAL when there is not enough room to store one object. The ABI
> -  will be preserved until 20.11.
> -
>  * ethdev: the legacy filter API, including
>    ``rte_eth_dev_filter_supported()``, ``rte_eth_dev_filter_ctrl()`` as well
>    as filter types MACVLAN, ETHERTYPE, FLEXIBLE, SYN, NTUPLE, TUNNEL, FDIR,
> diff --git a/doc/guides/rel_notes/release_20_05.rst b/doc/guides/rel_notes/release_20_05.rst
> index b124c3f287..ab20a7d021 100644
> --- a/doc/guides/rel_notes/release_20_05.rst
> +++ b/doc/guides/rel_notes/release_20_05.rst
> @@ -241,6 +241,10 @@ API Changes
>     Also, make sure to start the actual text at the margin.
>     =========================================================
>  
> +* mempool: The API of ``rte_mempool_populate_iova()`` and
> +  ``rte_mempool_populate_virt()`` changed to return 0 instead of -EINVAL
> +  when there is not enough room to store one object.
> +
>  
>  ABI Changes
>  -----------
> diff --git a/examples/ntb/ntb_fwd.c b/examples/ntb/ntb_fwd.c
> index d49189e175..eba8ebf9fa 100644
> --- a/examples/ntb/ntb_fwd.c
> +++ b/examples/ntb/ntb_fwd.c
> @@ -1319,7 +1319,7 @@ ntb_mbuf_pool_create(uint16_t mbuf_seg_size, uint32_t nb_mbuf,
>  					mz->len - ntb_info.ntb_hdr_size,
>  					ntb_mempool_mz_free,
>  					(void *)(uintptr_t)mz);
> -		if (ret < 0) {
> +		if (ret <= 0) {
>  			rte_memzone_free(mz);
>  			rte_mempool_free(mp);
>  			return NULL;
> diff --git a/lib/librte_mempool/meson.build b/lib/librte_mempool/meson.build
> index a6e861cbfc..7dbe6b9bea 100644
> --- a/lib/librte_mempool/meson.build
> +++ b/lib/librte_mempool/meson.build
> @@ -9,6 +9,8 @@ foreach flag: extra_flags
>  	endif
>  endforeach
>  
> +use_function_versioning = true
> +
>  sources = files('rte_mempool.c', 'rte_mempool_ops.c',
>  		'rte_mempool_ops_default.c', 'mempool_trace_points.c')
>  headers = files('rte_mempool.h', 'rte_mempool_trace.h',
> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
> index 0be8f9f59d..edbdafaafb 100644
> --- a/lib/librte_mempool/rte_mempool.c
> +++ b/lib/librte_mempool/rte_mempool.c
> @@ -31,6 +31,7 @@
>  #include <rte_string_fns.h>
>  #include <rte_spinlock.h>
>  #include <rte_tailq.h>
> +#include <rte_function_versioning.h>
>  
>  #include "rte_mempool.h"
>  #include "rte_mempool_trace.h"
> @@ -303,12 +304,17 @@ mempool_ops_alloc_once(struct rte_mempool *mp)
>  	return 0;
>  }
>  
> +__vsym int
> +rte_mempool_populate_iova_v20_0_2(struct rte_mempool *mp, char *vaddr,
> +	rte_iova_t iova, size_t len, rte_mempool_memchunk_free_cb_t *free_cb,
> +	void *opaque);
> +
>  /* Add objects in the pool, using a physically contiguous memory
>   * zone. Return the number of objects added, or a negative value
>   * on error.
>   */
> -static int
> -__rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
> +__vsym int
> +rte_mempool_populate_iova_v20_0_2(struct rte_mempool *mp, char *vaddr,
>  	rte_iova_t iova, size_t len, rte_mempool_memchunk_free_cb_t *free_cb,
>  	void *opaque)
>  {
> @@ -366,14 +372,27 @@ __rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
>  	return ret;
>  }
>  
> -int
> -rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
> +BIND_DEFAULT_SYMBOL(rte_mempool_populate_iova, _v20_0_2, 20.0.2);
as discussed v21.

> +MAP_STATIC_SYMBOL(
> +	int rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
> +				rte_iova_t iova, size_t len,
> +				rte_mempool_memchunk_free_cb_t *free_cb,
> +				void *opaque),
> +	rte_mempool_populate_iova_v20_0_2);
> +
> +__vsym int
> +rte_mempool_populate_iova_v20(struct rte_mempool *mp, char *vaddr,
> +	rte_iova_t iova, size_t len, rte_mempool_memchunk_free_cb_t *free_cb,
> +	void *opaque);
> +
> +__vsym int
> +rte_mempool_populate_iova_v20(struct rte_mempool *mp, char *vaddr,
>  	rte_iova_t iova, size_t len, rte_mempool_memchunk_free_cb_t *free_cb,
>  	void *opaque)
>  {
>  	int ret;
>  
> -	ret = __rte_mempool_populate_iova(mp, vaddr, iova, len, free_cb,
> +	ret = rte_mempool_populate_iova_v20_0_2(mp, vaddr, iova, len, free_cb,
>  					opaque);
>  	if (ret == 0)
>  		ret = -EINVAL;
> @@ -381,6 +400,7 @@ rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
>  	rte_mempool_trace_populate_iova(mp, vaddr, iova, len, free_cb, opaque);
>  	return ret;
>  }
> +VERSION_SYMBOL(rte_mempool_populate_iova, _v20_0, 20.0);

this should be

VERSION_SYMBOL(rte_mempool_populate_iova, _v20, 20.0);

>  
>  static rte_iova_t
>  get_iova(void *addr)
> @@ -395,11 +415,16 @@ get_iova(void *addr)
>  	return ms->iova + RTE_PTR_DIFF(addr, ms->addr);
>  }
>  
> +__vsym int
> +rte_mempool_populate_virt_v20_0_2(struct rte_mempool *mp, char *addr,
> +	size_t len, size_t pg_sz, rte_mempool_memchunk_free_cb_t *free_cb,
> +	void *opaque);
> +
>  /* Populate the mempool with a virtual area. Return the number of
>   * objects added, or a negative value on error.
>   */
> -int
> -rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
> +__vsym int
> +rte_mempool_populate_virt_v20_0_2(struct rte_mempool *mp, char *addr,
>  	size_t len, size_t pg_sz, rte_mempool_memchunk_free_cb_t *free_cb,
>  	void *opaque)
>  {
> @@ -432,7 +457,7 @@ rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
>  				break;
>  		}
>  
> -		ret = __rte_mempool_populate_iova(mp, addr + off, iova,
> +		ret = rte_mempool_populate_iova_v20_0_2(mp, addr + off, iova,
>  			phys_len, free_cb, opaque);
>  		if (ret == 0)
>  			continue;
> @@ -443,9 +468,6 @@ rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
>  		cnt += ret;
>  	}
>  
> -	if (cnt == 0)
> -		return -EINVAL;
> -
>  	rte_mempool_trace_populate_virt(mp, addr, len, pg_sz, free_cb, opaque);
>  	return cnt;
>  
> @@ -453,6 +475,35 @@ rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
>  	rte_mempool_free_memchunks(mp);
>  	return ret;
>  }
> +BIND_DEFAULT_SYMBOL(rte_mempool_populate_virt, _v20_0_2, 20.0.2);
as discussed v21.

> +MAP_STATIC_SYMBOL(
> +	int rte_mempool_populate_virt(struct rte_mempool *mp,
> +				char *addr, size_t len, size_t pg_sz,
> +				rte_mempool_memchunk_free_cb_t *free_cb,
> +				void *opaque),
> +	rte_mempool_populate_virt_v20_0_2);
> +
> +__vsym int
> +rte_mempool_populate_virt_v20(struct rte_mempool *mp, char *addr,
> +	size_t len, size_t pg_sz, rte_mempool_memchunk_free_cb_t *free_cb,
> +	void *opaque);
> +
> +__vsym int
> +rte_mempool_populate_virt_v20(struct rte_mempool *mp, char *addr,
> +	size_t len, size_t pg_sz, rte_mempool_memchunk_free_cb_t *free_cb,
> +	void *opaque)
> +{
> +	int ret;
> +
> +	ret = rte_mempool_populate_virt_v20_0_2(mp, addr, len, pg_sz,
> +						free_cb, opaque);
> +
> +	if (ret == 0)
> +		ret = -EINVAL;
> +
> +	return ret;
> +}
> +VERSION_SYMBOL(rte_mempool_populate_virt, _v20_0, 20.0);

this should be
VERSION_SYMBOL(rte_mempool_populate_virt, _v20, 20.0);


>  
>  /* Get the minimal page size used in a mempool before populating it. */
>  int
> @@ -609,6 +660,8 @@ rte_mempool_populate_default(struct rte_mempool *mp)
>  				mz->len, pg_sz,
>  				rte_mempool_memchunk_mz_free,
>  				(void *)(uintptr_t)mz);
> +		if (ret == 0) /* should not happen */
> +			ret = -ENOBUFS;
>  		if (ret < 0) {
>  			rte_memzone_free(mz);
>  			goto fail;
> @@ -701,6 +754,8 @@ rte_mempool_populate_anon(struct rte_mempool *mp)
>  
>  	ret = rte_mempool_populate_virt(mp, addr, size, getpagesize(),
>  		rte_mempool_memchunk_anon_free, addr);
> +	if (ret == 0) /* should not happen */
> +		ret = -ENOBUFS;
>  	if (ret < 0) {
>  		rte_errno = -ret;
>  		goto fail;
> diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
> index 6e0573ea42..652d19f9f1 100644
> --- a/lib/librte_mempool/rte_mempool.h
> +++ b/lib/librte_mempool/rte_mempool.h
> @@ -1112,9 +1112,12 @@ rte_mempool_free(struct rte_mempool *mp);
>   * @param opaque
>   *   An opaque argument passed to free_cb.
>   * @return
> - *   The number of objects added on success.
> + *   The number of objects added on success (strictly positive).
>   *   On error, the chunk is not added in the memory list of the
> - *   mempool and a negative errno is returned.
> + *   mempool the following code is returned:
> + *     (0): not enough room in chunk for one object.
> + *     (-ENOSPC): mempool is already populated.
> + *     (-ENOMEM): allocation failure.
>   */
>  int rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
>  	rte_iova_t iova, size_t len, rte_mempool_memchunk_free_cb_t *free_cb,
> @@ -1139,9 +1142,12 @@ int rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
>   * @param opaque
>   *   An opaque argument passed to free_cb.
>   * @return
> - *   The number of objects added on success.
> + *   The number of objects added on success (strictly positive).
>   *   On error, the chunk is not added in the memory list of the
> - *   mempool and a negative errno is returned.
> + *   mempool the following code is returned:
> + *     (0): not enough room in chunk for one object.
> + *     (-ENOSPC): mempool is already populated.
> + *     (-ENOMEM): allocation failure.
>   */
>  int
>  rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
> diff --git a/lib/librte_mempool/rte_mempool_version.map b/lib/librte_mempool/rte_mempool_version.map
> index 695dd6e04f..9e58093665 100644
> --- a/lib/librte_mempool/rte_mempool_version.map
> +++ b/lib/librte_mempool/rte_mempool_version.map
> @@ -31,6 +31,13 @@ DPDK_20.0 {
>  	local: *;
>  };
>  
> +DPDK_20.0.2 {

as discussed DPDK_21

> +	global:
> +
> +	rte_mempool_populate_iova;
> +	rte_mempool_populate_virt;
> +} DPDK_20.0;
> +
>  EXPERIMENTAL {
>  	global:
>  
>