minor bpf improvements

PATCH Superseded Stephen Hemminger 2 participants 8 messages Oct 19, 2025 – Oct 20, 2025 Arm/Amlogic Meson SoC support

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Stephen Hemminger

author

2025-10-19 17:00 UTC #0 lore raw

cover minor bpf improvements

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(-)

Signature · 1 line

2.51.0

Stephen Hemminger

author

2025-10-19 17:00 UTC #1 lore raw

PATCH 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 <[email protected]>

---
 lib/bpf/rte_bpf.h | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

lib/bpf/rte_bpf.h +8 -3

index 80ebb0210f..309d84bc51 100644
@@ -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
 }

Signature · 1 line

2.51.0

Stephen Hemminger

author

2025-10-19 17:00 UTC #2 lore raw

PATCH 2/2 bpf: remove dependency on vla

In reply to 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 <[email protected]>

---
 lib/bpf/bpf_pkt.c   | 16 +++++++++-------
 lib/bpf/meson.build |  2 --
 2 files changed, 9 insertions(+), 9 deletions(-)

lib/bpf/bpf_pkt.c +9 -7

index 01f813c56b..6a425d79b6 100644
@@ -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++) {

lib/bpf/meson.build +0 -2

index 28df7f469a..aa258a9061 100644
@@ -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'

Signature · 1 line

2.51.0

Stephen Hemminger

author

2025-10-19 20:41 UTC #3 lore raw

v2 cover minor bpf improvements

In reply to 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(-)

Signature · 1 line

2.51.0

Stephen Hemminger

author

2025-10-19 20:41 UTC #4 lore raw

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

Signed-off-by Stephen Hemminger <[email protected]>

---
 lib/bpf/rte_bpf.h | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

lib/bpf/rte_bpf.h +8 -3

index 80ebb0210f..309d84bc51 100644
@@ -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
 }

Signature · 1 line

2.51.0

Konstantin Ananyev

Acked-by on v2 1/2

2025-10-20 14:53 UTC #5 lore raw

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

Quoted 55 lines

-----Original Message-----
From: Stephen Hemminger <[email protected]>
Sent: Sunday, October 19, 2025 9:40 PM
To: [email protected]
Cc: Stephen Hemminger <[email protected]>; Konstantin Ananyev <[email protected]>
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 <[email protected]>
---
 lib/bpf/rte_bpf.h | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
lib/bpf/rte_bpf.h +6 -2
index 80ebb0210f..309d84bc51 100644
@@ -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.
  *

lib/bpf/rte_bpf.h struct bpf_program;

Quoted 10 lines

lib/bpf/rte_bpf.h +2 -2

@@ -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 <[email protected]>

Quoted 1 line

2.51.0

Stephen Hemminger

author

2025-10-19 20:41 UTC #6 lore raw

PATCH v2 2/2 bpf: remove dependency on vla

In reply to 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 <[email protected]>

---
 lib/bpf/bpf_pkt.c   | 16 +++++++++-------
 lib/bpf/meson.build |  2 --
 2 files changed, 9 insertions(+), 9 deletions(-)

lib/bpf/bpf_pkt.c +9 -7

index 01f813c56b..6a425d79b6 100644
@@ -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++) {

lib/bpf/meson.build +0 -2

index 28df7f469a..aa258a9061 100644
@@ -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'

Signature · 1 line

2.51.0

Konstantin Ananyev

2025-10-20 14:56 UTC #7 lore raw

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

Quoted 5 lines

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

Quoted 90 lines

Signed-off-by Stephen Hemminger <[email protected]>

---
 lib/bpf/bpf_pkt.c   | 16 +++++++++-------
 lib/bpf/meson.build |  2 --
 2 files changed, 9 insertions(+), 9 deletions(-)

lib/bpf/bpf_pkt.c +4 -2

index 01f813c56b..6a425d79b6 100644
@@ -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)

lib/bpf/bpf_pkt.c +2 -2

 			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++)

lib/bpf/bpf_pkt.c +1 -1

 		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;

lib/bpf/bpf_pkt.c +1 -1

 	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);

lib/bpf/bpf_pkt.c +1 -1

 	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;

lib/bpf/bpf_pkt.c +0 -0

 	for (i = 0; i != num; i++) {

lib/bpf/meson.build +0 -3

index 28df7f469a..aa258a9061 100644
@@ -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