[PATCH 0/2] minor bpf improvements

[PATCH 0/2] minor bpf improvements

[Stephen Hemminger]

Minor update to BPF. Add allocation annotation and remove VLA.

Stephen Hemminger (2):
  bpf: add allocation annotations to functions
  bpf: remove dependency on vla

 lib/bpf/bpf_pkt.c   | 16 +++++++++-------
 lib/bpf/meson.build |  2 --
 lib/bpf/rte_bpf.h   | 11 ++++++++---
 3 files changed, 17 insertions(+), 12 deletions(-)

-- 
2.51.0

[PATCH 1/2] bpf: add allocation annotations to functions

[Stephen Hemminger]

In commit 80da7efbb4c4 ("eal: annotate allocation functions")
helper macros were added to provide compiler information to
detect misuse of alloc/free combinations. This covered many
of the functions in DPDK but missed the case of data allocated
by BPF load functions.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 lib/bpf/rte_bpf.h | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/lib/bpf/rte_bpf.h b/lib/bpf/rte_bpf.h
index 80ebb0210f..309d84bc51 100644
--- a/lib/bpf/rte_bpf.h
+++ b/lib/bpf/rte_bpf.h
@@ -18,6 +18,7 @@
 
 #include <rte_common.h>
 #include <rte_mbuf.h>
+#include <rte_malloc.h>
 #include <bpf_def.h>
 
 #ifdef __cplusplus
@@ -128,7 +129,8 @@ rte_bpf_destroy(struct rte_bpf *bpf);
  *   - ENOMEM - can't reserve enough memory
  */
 struct rte_bpf *
-rte_bpf_load(const struct rte_bpf_prm *prm);
+rte_bpf_load(const struct rte_bpf_prm *prm)
+	__rte_malloc __rte_dealloc(rte_bpf_destroy, 1);
 
 /**
  * Create a new eBPF execution context and load BPF code from given ELF
@@ -152,7 +154,9 @@ rte_bpf_load(const struct rte_bpf_prm *prm);
  */
 struct rte_bpf *
 rte_bpf_elf_load(const struct rte_bpf_prm *prm, const char *fname,
-		const char *sname);
+		const char *sname)
+	__rte_malloc __rte_dealloc(rte_bpf_destroy, 1);
+
 /**
  * Execute given BPF bytecode.
  *
@@ -228,7 +232,8 @@ struct bpf_program;
  *   - ENOTSUP - operation not supported
  */
 struct rte_bpf_prm *
-rte_bpf_convert(const struct bpf_program *prog);
+rte_bpf_convert(const struct bpf_program *prog)
+	__rte_malloc __rte_dealloc_free;
 
 #ifdef __cplusplus
 }
-- 
2.51.0

[PATCH 2/2] bpf: remove dependency on vla

[Stephen Hemminger]

The code for ethdev callbacks was using variable length arrays
which is a feature not supported on MSVC and later C standards.
Replace with alloca().

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 lib/bpf/bpf_pkt.c   | 16 +++++++++-------
 lib/bpf/meson.build |  2 --
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/lib/bpf/bpf_pkt.c b/lib/bpf/bpf_pkt.c
index 01f813c56b..6a425d79b6 100644
--- a/lib/bpf/bpf_pkt.c
+++ b/lib/bpf/bpf_pkt.c
@@ -6,6 +6,7 @@
 #include <string.h>
 #include <errno.h>
 #include <stdint.h>
+#include <alloca.h>
 
 #include <sys/queue.h>
 
@@ -163,10 +164,11 @@ apply_filter(struct rte_mbuf *mb[], const uint64_t rc[], uint32_t num,
 	uint32_t drop)
 {
 	uint32_t i, j, k;
-	struct rte_mbuf *dr[num];
+	struct rte_mbuf **dr;
 
-	for (i = 0, j = 0, k = 0; i != num; i++) {
+	dr = alloca(sizeof(struct rte_mbuf *) * num);
 
+	for (i = 0, j = 0, k = 0; i != num; i++) {
 		/* filter matches */
 		if (rc[i] != 0)
 			mb[j++] = mb[i];
@@ -193,8 +195,8 @@ pkt_filter_vm(const struct rte_bpf *bpf, struct rte_mbuf *mb[], uint32_t num,
 	uint32_t drop)
 {
 	uint32_t i;
-	void *dp[num];
-	uint64_t rc[num];
+	void **dp = alloca(sizeof(void *) * num);
+	uint64_t *rc = alloca(sizeof(uint64_t) * num);
 
 	for (i = 0; i != num; i++)
 		dp[i] = rte_pktmbuf_mtod(mb[i], void *);
@@ -209,7 +211,7 @@ pkt_filter_jit(const struct rte_bpf_jit *jit, struct rte_mbuf *mb[],
 {
 	uint32_t i, n;
 	void *dp;
-	uint64_t rc[num];
+	uint64_t *rc = alloca(sizeof(uint64_t) * num);
 
 	n = 0;
 	for (i = 0; i != num; i++) {
@@ -228,7 +230,7 @@ static inline uint32_t
 pkt_filter_mb_vm(const struct rte_bpf *bpf, struct rte_mbuf *mb[], uint32_t num,
 	uint32_t drop)
 {
-	uint64_t rc[num];
+	uint64_t *rc = alloca(sizeof(uint64_t) * num);
 
 	rte_bpf_exec_burst(bpf, (void **)mb, rc, num);
 	return apply_filter(mb, rc, num, drop);
@@ -239,7 +241,7 @@ pkt_filter_mb_jit(const struct rte_bpf_jit *jit, struct rte_mbuf *mb[],
 	uint32_t num, uint32_t drop)
 {
 	uint32_t i, n;
-	uint64_t rc[num];
+	uint64_t *rc = alloca(sizeof(uint64_t) * num);
 
 	n = 0;
 	for (i = 0; i != num; i++) {
diff --git a/lib/bpf/meson.build b/lib/bpf/meson.build
index 28df7f469a..aa258a9061 100644
--- a/lib/bpf/meson.build
+++ b/lib/bpf/meson.build
@@ -7,8 +7,6 @@ if is_windows
     subdir_done()
 endif
 
-cflags += no_wvla_cflag
-
 if arch_subdir == 'x86' and dpdk_conf.get('RTE_ARCH_32')
     build = false
     reason = 'not supported on 32-bit x86'
-- 
2.51.0

[PATCH v2 0/2] minor bpf improvements

[Stephen Hemminger]

Minor update to BPF. Add allocation annotation and remove VLA.

v2 - fix build on FreeBsd

Stephen Hemminger (2):
  bpf: add allocation annotations to functions
  bpf: remove dependency on vla

 lib/bpf/bpf_pkt.c   | 16 +++++++++-------
 lib/bpf/meson.build |  2 --
 lib/bpf/rte_bpf.h   | 11 ++++++++---
 3 files changed, 17 insertions(+), 12 deletions(-)

-- 
2.51.0

[PATCH v2 1/2] bpf: add allocation annotations to functions

[Stephen Hemminger]

In commit 80da7efbb4c4 ("eal: annotate allocation functions")
helper macros were added to provide compiler information to
detect misuse of alloc/free combinations. This covered many
of the functions in DPDK but missed the case of data allocated
by BPF load functions.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 lib/bpf/rte_bpf.h | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/lib/bpf/rte_bpf.h b/lib/bpf/rte_bpf.h
index 80ebb0210f..309d84bc51 100644
--- a/lib/bpf/rte_bpf.h
+++ b/lib/bpf/rte_bpf.h
@@ -18,6 +18,7 @@
 
 #include <rte_common.h>
 #include <rte_mbuf.h>
+#include <rte_malloc.h>
 #include <bpf_def.h>
 
 #ifdef __cplusplus
@@ -128,7 +129,8 @@ rte_bpf_destroy(struct rte_bpf *bpf);
  *   - ENOMEM - can't reserve enough memory
  */
 struct rte_bpf *
-rte_bpf_load(const struct rte_bpf_prm *prm);
+rte_bpf_load(const struct rte_bpf_prm *prm)
+	__rte_malloc __rte_dealloc(rte_bpf_destroy, 1);
 
 /**
  * Create a new eBPF execution context and load BPF code from given ELF
@@ -152,7 +154,9 @@ rte_bpf_load(const struct rte_bpf_prm *prm);
  */
 struct rte_bpf *
 rte_bpf_elf_load(const struct rte_bpf_prm *prm, const char *fname,
-		const char *sname);
+		const char *sname)
+	__rte_malloc __rte_dealloc(rte_bpf_destroy, 1);
+
 /**
  * Execute given BPF bytecode.
  *
@@ -228,7 +232,8 @@ struct bpf_program;
  *   - ENOTSUP - operation not supported
  */
 struct rte_bpf_prm *
-rte_bpf_convert(const struct bpf_program *prog);
+rte_bpf_convert(const struct bpf_program *prog)
+	__rte_malloc __rte_dealloc_free;
 
 #ifdef __cplusplus
 }
-- 
2.51.0

RE: [PATCH v2 1/2] bpf: add allocation annotations to functions

[Konstantin Ananyev]

> -----Original Message-----
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Sunday, October 19, 2025 9:40 PM
> To: dev@dpdk.org
> Cc: Stephen Hemminger <stephen@networkplumber.org>; Konstantin Ananyev
> <konstantin.ananyev@huawei.com>
> Subject: [PATCH v2 1/2] bpf: add allocation annotations to functions
> 
> In commit 80da7efbb4c4 ("eal: annotate allocation functions")
> helper macros were added to provide compiler information to
> detect misuse of alloc/free combinations. This covered many
> of the functions in DPDK but missed the case of data allocated
> by BPF load functions.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
>  lib/bpf/rte_bpf.h | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/bpf/rte_bpf.h b/lib/bpf/rte_bpf.h
> index 80ebb0210f..309d84bc51 100644
> --- a/lib/bpf/rte_bpf.h
> +++ b/lib/bpf/rte_bpf.h
> @@ -18,6 +18,7 @@
> 
>  #include <rte_common.h>
>  #include <rte_mbuf.h>
> +#include <rte_malloc.h>
>  #include <bpf_def.h>
> 
>  #ifdef __cplusplus
> @@ -128,7 +129,8 @@ rte_bpf_destroy(struct rte_bpf *bpf);
>   *   - ENOMEM - can't reserve enough memory
>   */
>  struct rte_bpf *
> -rte_bpf_load(const struct rte_bpf_prm *prm);
> +rte_bpf_load(const struct rte_bpf_prm *prm)
> +	__rte_malloc __rte_dealloc(rte_bpf_destroy, 1);
> 
>  /**
>   * Create a new eBPF execution context and load BPF code from given ELF
> @@ -152,7 +154,9 @@ rte_bpf_load(const struct rte_bpf_prm *prm);
>   */
>  struct rte_bpf *
>  rte_bpf_elf_load(const struct rte_bpf_prm *prm, const char *fname,
> -		const char *sname);
> +		const char *sname)
> +	__rte_malloc __rte_dealloc(rte_bpf_destroy, 1);
> +
>  /**
>   * Execute given BPF bytecode.
>   *
> @@ -228,7 +232,8 @@ struct bpf_program;
>   *   - ENOTSUP - operation not supported
>   */
>  struct rte_bpf_prm *
> -rte_bpf_convert(const struct bpf_program *prog);
> +rte_bpf_convert(const struct bpf_program *prog)
> +	__rte_malloc __rte_dealloc_free;
> 
>  #ifdef __cplusplus
>  }
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev@huawei.com>

> 2.51.0

[PATCH v2 2/2] bpf: remove dependency on vla

[Stephen Hemminger]

The code for ethdev callbacks was using variable length arrays
which is a feature not supported on MSVC and later C standards.
Replace with alloca().

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 lib/bpf/bpf_pkt.c   | 16 +++++++++-------
 lib/bpf/meson.build |  2 --
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/lib/bpf/bpf_pkt.c b/lib/bpf/bpf_pkt.c
index 01f813c56b..6a425d79b6 100644
--- a/lib/bpf/bpf_pkt.c
+++ b/lib/bpf/bpf_pkt.c
@@ -6,6 +6,7 @@
 #include <string.h>
 #include <errno.h>
 #include <stdint.h>
+#include <alloca.h>
 
 #include <sys/queue.h>
 
@@ -163,10 +164,11 @@ apply_filter(struct rte_mbuf *mb[], const uint64_t rc[], uint32_t num,
 	uint32_t drop)
 {
 	uint32_t i, j, k;
-	struct rte_mbuf *dr[num];
+	struct rte_mbuf **dr;
 
-	for (i = 0, j = 0, k = 0; i != num; i++) {
+	dr = alloca(sizeof(struct rte_mbuf *) * num);
 
+	for (i = 0, j = 0, k = 0; i != num; i++) {
 		/* filter matches */
 		if (rc[i] != 0)
 			mb[j++] = mb[i];
@@ -193,8 +195,8 @@ pkt_filter_vm(const struct rte_bpf *bpf, struct rte_mbuf *mb[], uint32_t num,
 	uint32_t drop)
 {
 	uint32_t i;
-	void *dp[num];
-	uint64_t rc[num];
+	void **dp = alloca(sizeof(void *) * num);
+	uint64_t *rc = alloca(sizeof(uint64_t) * num);
 
 	for (i = 0; i != num; i++)
 		dp[i] = rte_pktmbuf_mtod(mb[i], void *);
@@ -209,7 +211,7 @@ pkt_filter_jit(const struct rte_bpf_jit *jit, struct rte_mbuf *mb[],
 {
 	uint32_t i, n;
 	void *dp;
-	uint64_t rc[num];
+	uint64_t *rc = alloca(sizeof(uint64_t) * num);
 
 	n = 0;
 	for (i = 0; i != num; i++) {
@@ -228,7 +230,7 @@ static inline uint32_t
 pkt_filter_mb_vm(const struct rte_bpf *bpf, struct rte_mbuf *mb[], uint32_t num,
 	uint32_t drop)
 {
-	uint64_t rc[num];
+	uint64_t *rc = alloca(sizeof(uint64_t) * num);
 
 	rte_bpf_exec_burst(bpf, (void **)mb, rc, num);
 	return apply_filter(mb, rc, num, drop);
@@ -239,7 +241,7 @@ pkt_filter_mb_jit(const struct rte_bpf_jit *jit, struct rte_mbuf *mb[],
 	uint32_t num, uint32_t drop)
 {
 	uint32_t i, n;
-	uint64_t rc[num];
+	uint64_t *rc = alloca(sizeof(uint64_t) * num);
 
 	n = 0;
 	for (i = 0; i != num; i++) {
diff --git a/lib/bpf/meson.build b/lib/bpf/meson.build
index 28df7f469a..aa258a9061 100644
--- a/lib/bpf/meson.build
+++ b/lib/bpf/meson.build
@@ -7,8 +7,6 @@ if is_windows
     subdir_done()
 endif
 
-cflags += no_wvla_cflag
-
 if arch_subdir == 'x86' and dpdk_conf.get('RTE_ARCH_32')
     build = false
     reason = 'not supported on 32-bit x86'
-- 
2.51.0

RE: [PATCH v2 2/2] bpf: remove dependency on vla

[Konstantin Ananyev]

> The code for ethdev callbacks was using variable length arrays
> which is a feature not supported on MSVC and later C standards.
> Replace with alloca().

That looks exactly the same as first version of the patch.
So I can only repeat my comment for previous version:

I am not a big fun of such mechanical replacement of vla with alloca()
Specially in that particular case, we can have internal function that uses
fixed size array and in public one just call it several times in a loop.
Again, using VLA here is probably a real security breach,
as we put some assumptions on size of input arrays provided by user,
which we probably shouldn't.    

Konstantin

> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
>  lib/bpf/bpf_pkt.c   | 16 +++++++++-------
>  lib/bpf/meson.build |  2 --
>  2 files changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/lib/bpf/bpf_pkt.c b/lib/bpf/bpf_pkt.c
> index 01f813c56b..6a425d79b6 100644
> --- a/lib/bpf/bpf_pkt.c
> +++ b/lib/bpf/bpf_pkt.c
> @@ -6,6 +6,7 @@
>  #include <string.h>
>  #include <errno.h>
>  #include <stdint.h>
> +#include <alloca.h>
> 
>  #include <sys/queue.h>
> 
> @@ -163,10 +164,11 @@ apply_filter(struct rte_mbuf *mb[], const uint64_t rc[],
> uint32_t num,
>  	uint32_t drop)
>  {
>  	uint32_t i, j, k;
> -	struct rte_mbuf *dr[num];
> +	struct rte_mbuf **dr;
> 
> -	for (i = 0, j = 0, k = 0; i != num; i++) {
> +	dr = alloca(sizeof(struct rte_mbuf *) * num);
> 
> +	for (i = 0, j = 0, k = 0; i != num; i++) {
>  		/* filter matches */
>  		if (rc[i] != 0)
>  			mb[j++] = mb[i];
> @@ -193,8 +195,8 @@ pkt_filter_vm(const struct rte_bpf *bpf, struct rte_mbuf
> *mb[], uint32_t num,
>  	uint32_t drop)
>  {
>  	uint32_t i;
> -	void *dp[num];
> -	uint64_t rc[num];
> +	void **dp = alloca(sizeof(void *) * num);
> +	uint64_t *rc = alloca(sizeof(uint64_t) * num);
> 
>  	for (i = 0; i != num; i++)
>  		dp[i] = rte_pktmbuf_mtod(mb[i], void *);
> @@ -209,7 +211,7 @@ pkt_filter_jit(const struct rte_bpf_jit *jit, struct rte_mbuf
> *mb[],
>  {
>  	uint32_t i, n;
>  	void *dp;
> -	uint64_t rc[num];
> +	uint64_t *rc = alloca(sizeof(uint64_t) * num);
> 
>  	n = 0;
>  	for (i = 0; i != num; i++) {
> @@ -228,7 +230,7 @@ static inline uint32_t
>  pkt_filter_mb_vm(const struct rte_bpf *bpf, struct rte_mbuf *mb[], uint32_t
> num,
>  	uint32_t drop)
>  {
> -	uint64_t rc[num];
> +	uint64_t *rc = alloca(sizeof(uint64_t) * num);
> 
>  	rte_bpf_exec_burst(bpf, (void **)mb, rc, num);
>  	return apply_filter(mb, rc, num, drop);
> @@ -239,7 +241,7 @@ pkt_filter_mb_jit(const struct rte_bpf_jit *jit, struct
> rte_mbuf *mb[],
>  	uint32_t num, uint32_t drop)
>  {
>  	uint32_t i, n;
> -	uint64_t rc[num];
> +	uint64_t *rc = alloca(sizeof(uint64_t) * num);
> 
>  	n = 0;
>  	for (i = 0; i != num; i++) {
> diff --git a/lib/bpf/meson.build b/lib/bpf/meson.build
> index 28df7f469a..aa258a9061 100644
> --- a/lib/bpf/meson.build
> +++ b/lib/bpf/meson.build
> @@ -7,8 +7,6 @@ if is_windows
>      subdir_done()
>  endif
> 
> -cflags += no_wvla_cflag
> -
>  if arch_subdir == 'x86' and dpdk_conf.get('RTE_ARCH_32')
>      build = false
>      reason = 'not supported on 32-bit x86'
> --
> 2.51.0