[dpdk-dev] [PATCH v3 2/2] bpf: fix convert API can be undefined

[Konstantin Ananyev <konstantin.ananyev@intel.com>]

rte_bpf_convert() implementation depends on libpcap.
Right now it is defined only when this library is installed and
RTE_PORT_PCAP is defined.
Fix that by providing for such case stub rte_bpf_convert()
implementation that will always return an error.
To draw user attention, if proper implementation is disabled,
warning will be thrown at meson configure stage.
Also move stub for another function (rte_bpf_elf_load) into
the same place (bpf_stub.c).

Fixes: 2eccf6afbea9 ("bpf: add function to convert classic BPF to DPDK BPF")

Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
---
 app/dumpcap/main.c  |  3 ++-
 lib/bpf/bpf_load.c  | 18 ------------------
 lib/bpf/bpf_stub.c  | 45 +++++++++++++++++++++++++++++++++++++++++++++
 lib/bpf/meson.build |  5 +++++
 lib/bpf/rte_bpf.h   |  5 +----
 5 files changed, 53 insertions(+), 23 deletions(-)
 create mode 100644 lib/bpf/bpf_stub.c

diff --git a/app/dumpcap/main.c b/app/dumpcap/main.c
index baf9eee466..c5fe440302 100644
--- a/app/dumpcap/main.c
+++ b/app/dumpcap/main.c
@@ -285,7 +285,8 @@ static void compile_filter(void)
 	bpf_prm = rte_bpf_convert(&bf);
 	if (bpf_prm == NULL)
 		rte_exit(EXIT_FAILURE,
-			 "bpf convert failed\n");
+			 "bpf convert failed: %s(%d)\n",
+			 rte_strerror(rte_errno), rte_errno);
 
 	if (dump_bpf) {
 		printf("cBPF program (%u insns)\n", bf.bf_len);
diff --git a/lib/bpf/bpf_load.c b/lib/bpf/bpf_load.c
index 2a3b901d74..272f2ba11b 100644
--- a/lib/bpf/bpf_load.c
+++ b/lib/bpf/bpf_load.c
@@ -130,21 +130,3 @@ rte_bpf_load(const struct rte_bpf_prm *prm)
 
 	return bpf;
 }
-
-#ifndef RTE_LIBRTE_BPF_ELF
-struct rte_bpf *
-rte_bpf_elf_load(const struct rte_bpf_prm *prm, const char *fname,
-	const char *sname)
-{
-	if (prm == NULL || fname == NULL || sname == NULL) {
-		rte_errno = EINVAL;
-		return NULL;
-	}
-
-	RTE_BPF_LOG(ERR, "%s() is not supported with current config\n"
-		"rebuild with libelf installed\n",
-		__func__);
-	rte_errno = ENOTSUP;
-	return NULL;
-}
-#endif
diff --git a/lib/bpf/bpf_stub.c b/lib/bpf/bpf_stub.c
new file mode 100644
index 0000000000..caec00f42f
--- /dev/null
+++ b/lib/bpf/bpf_stub.c
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2018-2021 Intel Corporation
+ */
+
+#include "bpf_impl.h"
+#include <rte_errno.h>
+
+/**
+ * Contains stubs for unimplemented public API functions
+ */
+
+#ifndef RTE_LIBRTE_BPF_ELF
+struct rte_bpf *
+rte_bpf_elf_load(const struct rte_bpf_prm *prm, const char *fname,
+	const char *sname)
+{
+	if (prm == NULL || fname == NULL || sname == NULL) {
+		rte_errno = EINVAL;
+		return NULL;
+	}
+
+	RTE_BPF_LOG(ERR, "%s() is not supported with current config\n"
+		"rebuild with libelf installed\n",
+		__func__);
+	rte_errno = ENOTSUP;
+	return NULL;
+}
+#endif
+
+#ifndef RTE_PORT_PCAP
+struct rte_bpf_prm *
+rte_bpf_convert(const struct bpf_program *prog)
+{
+	if (prog == NULL) {
+		rte_errno = EINVAL;
+		return NULL;
+	}
+
+	RTE_BPF_LOG(ERR, "%s() is not supported with current config\n"
+		"rebuild with libpcap installed\n",
+		__func__);
+	rte_errno = ENOTSUP;
+	return NULL;
+}
+#endif
diff --git a/lib/bpf/meson.build b/lib/bpf/meson.build
index 33b506f3ac..0df55a2236 100644
--- a/lib/bpf/meson.build
+++ b/lib/bpf/meson.build
@@ -12,6 +12,7 @@ sources = files('bpf.c',
         'bpf_exec.c',
         'bpf_load.c',
         'bpf_pkt.c',
+        'bpf_stub.c',
         'bpf_validate.c')
 
 if arch_subdir == 'x86' and dpdk_conf.get('RTE_ARCH_64')
@@ -31,9 +32,13 @@ if dep.found()
     dpdk_conf.set('RTE_LIBRTE_BPF_ELF', 1)
     sources += files('bpf_load_elf.c')
     ext_deps += dep
+else
+     warning('libelf is missing, rte_bpf_elf_load API will be disabled')
 endif
 
 if dpdk_conf.has('RTE_PORT_PCAP')
     sources += files('bpf_convert.c')
     ext_deps += pcap_dep
+else
+     warning('RTE_PORT_PCAP is missing, rte_bpf_convert API will be disabled')
 endif
diff --git a/lib/bpf/rte_bpf.h b/lib/bpf/rte_bpf.h
index f09e36b65b..7e7d03b9c7 100644
--- a/lib/bpf/rte_bpf.h
+++ b/lib/bpf/rte_bpf.h
@@ -212,8 +212,6 @@ __rte_experimental
 void
 rte_bpf_dump(FILE *f, const struct ebpf_insn *buf, uint32_t len);
 
-#ifdef RTE_PORT_PCAP
-
 struct bpf_program;
 
 /**
@@ -228,13 +226,12 @@ struct bpf_program;
  *   Possible rte_errno errors include:
  *   - EINVAL - invalid parameter passed to function
  *   - ENOMEM - can't reserve enough memory
+ *   - ENOTSUP - operation not supported
  */
 __rte_experimental
 struct rte_bpf_prm *
 rte_bpf_convert(const struct bpf_program *prog);
 
-#endif
-
 #ifdef __cplusplus
 }
 #endif
-- 
2.25.1