Merge branch 'change-libbpf-print-api'

Yonghong Song says:

====================
These are patches responding to my comments for
Magnus's patch (https://patchwork.ozlabs.org/patch/1032848/).
The goal is to make pr_* macros available to other C files
than libbpf.c, and to simplify API function libbpf_set_print().

Specifically, Patch #1 used global functions
to facilitate pr_* macros in the header files so they
are available in different C files.
Patch #2 removes the global function libbpf_print_level_available()
which is added in Patch 1.
Patch #3 simplified libbpf_set_print() which takes only one print
function with a debug level argument among others.

Changelogs:
 v3 -> v4:
   . rename libbpf internal header util.h to libbpf_util.h
   . rename libbpf internal function libbpf_debug_print() to libbpf_print()
 v2 -> v3:
   . bailed out earlier in libbpf_debug_print() if __libbpf_pr is NULL
   . added missing LIBBPF_DEBUG level check in libbpf.c __base_pr().
 v1 -> v2:
   . Renamed global function libbpf_dprint() to libbpf_debug_print()
     to be more expressive.
   . Removed libbpf_dprint_level_available() as it is used only
     once in btf.c and we can remove it by optimizing for common cases.
====================
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/lib/bpf/btf.c

@@ -9,8 +9,9 @@
 #include <linux/btf.h>
 #include "btf.h"
 #include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_util.h"
 
-#define elog(fmt, ...) { if (err_log) err_log(fmt, ##__VA_ARGS__); }
 #define max(a, b) ((a) > (b) ? (a) : (b))
 #define min(a, b) ((a) < (b) ? (a) : (b))
 
@@ -107,54 +108,54 @@ static int btf_add_type(struct btf *btf, struct btf_type *t)
 	return 0;
 }
 
-static int btf_parse_hdr(struct btf *btf, btf_print_fn_t err_log)
+static int btf_parse_hdr(struct btf *btf)
 {
 	const struct btf_header *hdr = btf->hdr;
 	__u32 meta_left;
 
 	if (btf->data_size < sizeof(struct btf_header)) {
-		elog("BTF header not found\n");
+		pr_debug("BTF header not found\n");
 		return -EINVAL;
 	}
 
 	if (hdr->magic != BTF_MAGIC) {
-		elog("Invalid BTF magic:%x\n", hdr->magic);
+		pr_debug("Invalid BTF magic:%x\n", hdr->magic);
 		return -EINVAL;
 	}
 
 	if (hdr->version != BTF_VERSION) {
-		elog("Unsupported BTF version:%u\n", hdr->version);
+		pr_debug("Unsupported BTF version:%u\n", hdr->version);
 		return -ENOTSUP;
 	}
 
 	if (hdr->flags) {
-		elog("Unsupported BTF flags:%x\n", hdr->flags);
+		pr_debug("Unsupported BTF flags:%x\n", hdr->flags);
 		return -ENOTSUP;
 	}
 
 	meta_left = btf->data_size - sizeof(*hdr);
 	if (!meta_left) {
-		elog("BTF has no data\n");
+		pr_debug("BTF has no data\n");
 		return -EINVAL;
 	}
 
 	if (meta_left < hdr->type_off) {
-		elog("Invalid BTF type section offset:%u\n", hdr->type_off);
+		pr_debug("Invalid BTF type section offset:%u\n", hdr->type_off);
 		return -EINVAL;
 	}
 
 	if (meta_left < hdr->str_off) {
-		elog("Invalid BTF string section offset:%u\n", hdr->str_off);
+		pr_debug("Invalid BTF string section offset:%u\n", hdr->str_off);
 		return -EINVAL;
 	}
 
 	if (hdr->type_off >= hdr->str_off) {
-		elog("BTF type section offset >= string section offset. No type?\n");
+		pr_debug("BTF type section offset >= string section offset. No type?\n");
 		return -EINVAL;
 	}
 
 	if (hdr->type_off & 0x02) {
-		elog("BTF type section is not aligned to 4 bytes\n");
+		pr_debug("BTF type section is not aligned to 4 bytes\n");
 		return -EINVAL;
 	}
 
@@ -163,7 +164,7 @@ static int btf_parse_hdr(struct btf *btf, btf_print_fn_t err_log)
 	return 0;
 }
 
-static int btf_parse_str_sec(struct btf *btf, btf_print_fn_t err_log)
+static int btf_parse_str_sec(struct btf *btf)
 {
 	const struct btf_header *hdr = btf->hdr;
 	const char *start = btf->nohdr_data + hdr->str_off;
@@ -171,7 +172,7 @@ static int btf_parse_str_sec(struct btf *btf, btf_print_fn_t err_log)
 
 	if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_NAME_OFFSET ||
 	    start[0] || end[-1]) {
-		elog("Invalid BTF string section\n");
+		pr_debug("Invalid BTF string section\n");
 		return -EINVAL;
 	}
 
@@ -180,7 +181,7 @@ static int btf_parse_str_sec(struct btf *btf, btf_print_fn_t err_log)
 	return 0;
 }
 
-static int btf_parse_type_sec(struct btf *btf, btf_print_fn_t err_log)
+static int btf_parse_type_sec(struct btf *btf)
 {
 	struct btf_header *hdr = btf->hdr;
 	void *nohdr_data = btf->nohdr_data;
@@ -219,7 +220,7 @@ static int btf_parse_type_sec(struct btf *btf, btf_print_fn_t err_log)
 		case BTF_KIND_RESTRICT:
 			break;
 		default:
-			elog("Unsupported BTF_KIND:%u\n",
+			pr_debug("Unsupported BTF_KIND:%u\n",
 			     BTF_INFO_KIND(t->info));
 			return -EINVAL;
 		}
@@ -363,7 +364,7 @@ void btf__free(struct btf *btf)
 	free(btf);
 }
 
-struct btf *btf__new(__u8 *data, __u32 size, btf_print_fn_t err_log)
+struct btf *btf__new(__u8 *data, __u32 size)
 {
 	__u32 log_buf_size = 0;
 	char *log_buf = NULL;
@@ -376,16 +377,15 @@ struct btf *btf__new(__u8 *data, __u32 size, btf_print_fn_t err_log)
 
 	btf->fd = -1;
 
-	if (err_log) {
-		log_buf = malloc(BPF_LOG_BUF_SIZE);
-		if (!log_buf) {
-			err = -ENOMEM;
-			goto done;
-		}
-		*log_buf = 0;
-		log_buf_size = BPF_LOG_BUF_SIZE;
+	log_buf = malloc(BPF_LOG_BUF_SIZE);
+	if (!log_buf) {
+		err = -ENOMEM;
+		goto done;
 	}
 
+	*log_buf = 0;
+	log_buf_size = BPF_LOG_BUF_SIZE;
+
 	btf->data = malloc(size);
 	if (!btf->data) {
 		err = -ENOMEM;
@@ -400,21 +400,21 @@ struct btf *btf__new(__u8 *data, __u32 size, btf_print_fn_t err_log)
 
 	if (btf->fd == -1) {
 		err = -errno;
-		elog("Error loading BTF: %s(%d)\n", strerror(errno), errno);
+		pr_warning("Error loading BTF: %s(%d)\n", strerror(errno), errno);
 		if (log_buf && *log_buf)
-			elog("%s\n", log_buf);
+			pr_warning("%s\n", log_buf);
 		goto done;
 	}
 
-	err = btf_parse_hdr(btf, err_log);
+	err = btf_parse_hdr(btf);
 	if (err)
 		goto done;
 
-	err = btf_parse_str_sec(btf, err_log);
+	err = btf_parse_str_sec(btf);
 	if (err)
 		goto done;
 
-	err = btf_parse_type_sec(btf, err_log);
+	err = btf_parse_type_sec(btf);
 
 done:
 	free(log_buf);
@@ -491,7 +491,7 @@ int btf__get_from_id(__u32 id, struct btf **btf)
 		goto exit_free;
 	}
 
-	*btf = btf__new((__u8 *)(long)btf_info.btf, btf_info.btf_size, NULL);
+	*btf = btf__new((__u8 *)(long)btf_info.btf, btf_info.btf_size);
 	if (IS_ERR(*btf)) {
 		err = PTR_ERR(*btf);
 		*btf = NULL;
@@ -514,8 +514,7 @@ struct btf_ext_sec_copy_param {
 
 static int btf_ext_copy_info(struct btf_ext *btf_ext,
 			     __u8 *data, __u32 data_size,
-			     struct btf_ext_sec_copy_param *ext_sec,
-			     btf_print_fn_t err_log)
+			     struct btf_ext_sec_copy_param *ext_sec)
 {
 	const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
 	const struct btf_ext_info_sec *sinfo;
@@ -529,14 +528,14 @@ static int btf_ext_copy_info(struct btf_ext *btf_ext,
 	data_size -= hdr->hdr_len;
 
 	if (ext_sec->off & 0x03) {
-		elog(".BTF.ext %s section is not aligned to 4 bytes\n",
+		pr_debug(".BTF.ext %s section is not aligned to 4 bytes\n",
 		     ext_sec->desc);
 		return -EINVAL;
 	}
 
 	if (data_size < ext_sec->off ||
 	    ext_sec->len > data_size - ext_sec->off) {
-		elog("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
+		pr_debug("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
 		     ext_sec->desc, ext_sec->off, ext_sec->len);
 		return -EINVAL;
 	}
@@ -546,7 +545,7 @@ static int btf_ext_copy_info(struct btf_ext *btf_ext,
 
 	/* At least a record size */
 	if (info_left < sizeof(__u32)) {
-		elog(".BTF.ext %s record size not found\n", ext_sec->desc);
+		pr_debug(".BTF.ext %s record size not found\n", ext_sec->desc);
 		return -EINVAL;
 	}
 
@@ -554,7 +553,7 @@ static int btf_ext_copy_info(struct btf_ext *btf_ext,
 	record_size = *(__u32 *)info;
 	if (record_size < ext_sec->min_rec_size ||
 	    record_size & 0x03) {
-		elog("%s section in .BTF.ext has invalid record size %u\n",
+		pr_debug("%s section in .BTF.ext has invalid record size %u\n",
 		     ext_sec->desc, record_size);
 		return -EINVAL;
 	}
@@ -564,7 +563,7 @@ static int btf_ext_copy_info(struct btf_ext *btf_ext,
 
 	/* If no records, return failure now so .BTF.ext won't be used. */
 	if (!info_left) {
-		elog("%s section in .BTF.ext has no records", ext_sec->desc);
+		pr_debug("%s section in .BTF.ext has no records", ext_sec->desc);
 		return -EINVAL;
 	}
 
@@ -574,14 +573,14 @@ static int btf_ext_copy_info(struct btf_ext *btf_ext,
 		__u32 num_records;
 
 		if (info_left < sec_hdrlen) {
-			elog("%s section header is not found in .BTF.ext\n",
+			pr_debug("%s section header is not found in .BTF.ext\n",
 			     ext_sec->desc);
 			return -EINVAL;
 		}
 
 		num_records = sinfo->num_info;
 		if (num_records == 0) {
-			elog("%s section has incorrect num_records in .BTF.ext\n",
+			pr_debug("%s section has incorrect num_records in .BTF.ext\n",
 			     ext_sec->desc);
 			return -EINVAL;
 		}
@@ -589,7 +588,7 @@ static int btf_ext_copy_info(struct btf_ext *btf_ext,
 		total_record_size = sec_hdrlen +
 				    (__u64)num_records * record_size;
 		if (info_left < total_record_size) {
-			elog("%s section has incorrect num_records in .BTF.ext\n",
+			pr_debug("%s section has incorrect num_records in .BTF.ext\n",
 			     ext_sec->desc);
 			return -EINVAL;
 		}
@@ -610,8 +609,7 @@ static int btf_ext_copy_info(struct btf_ext *btf_ext,
 }
 
 static int btf_ext_copy_func_info(struct btf_ext *btf_ext,
-				  __u8 *data, __u32 data_size,
-				  btf_print_fn_t err_log)
+				  __u8 *data, __u32 data_size)
 {
 	const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
 	struct btf_ext_sec_copy_param param = {
@@ -622,12 +620,11 @@ static int btf_ext_copy_func_info(struct btf_ext *btf_ext,
 		.desc = "func_info"
 	};
 
-	return btf_ext_copy_info(btf_ext, data, data_size, &param, err_log);
+	return btf_ext_copy_info(btf_ext, data, data_size, &param);
 }
 
 static int btf_ext_copy_line_info(struct btf_ext *btf_ext,
-				  __u8 *data, __u32 data_size,
-				  btf_print_fn_t err_log)
+				  __u8 *data, __u32 data_size)
 {
 	const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
 	struct btf_ext_sec_copy_param param = {
@@ -638,37 +635,36 @@ static int btf_ext_copy_line_info(struct btf_ext *btf_ext,
 		.desc = "line_info",
 	};
 
-	return btf_ext_copy_info(btf_ext, data, data_size, &param, err_log);
+	return btf_ext_copy_info(btf_ext, data, data_size, &param);
 }
 
-static int btf_ext_parse_hdr(__u8 *data, __u32 data_size,
-			     btf_print_fn_t err_log)
+static int btf_ext_parse_hdr(__u8 *data, __u32 data_size)
 {
 	const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
 
 	if (data_size < offsetof(struct btf_ext_header, func_info_off) ||
 	    data_size < hdr->hdr_len) {
-		elog("BTF.ext header not found");
+		pr_debug("BTF.ext header not found");
 		return -EINVAL;
 	}
 
 	if (hdr->magic != BTF_MAGIC) {
-		elog("Invalid BTF.ext magic:%x\n", hdr->magic);
+		pr_debug("Invalid BTF.ext magic:%x\n", hdr->magic);
 		return -EINVAL;
 	}
 
 	if (hdr->version != BTF_VERSION) {
-		elog("Unsupported BTF.ext version:%u\n", hdr->version);
+		pr_debug("Unsupported BTF.ext version:%u\n", hdr->version);
 		return -ENOTSUP;
 	}
 
 	if (hdr->flags) {
-		elog("Unsupported BTF.ext flags:%x\n", hdr->flags);
+		pr_debug("Unsupported BTF.ext flags:%x\n", hdr->flags);
 		return -ENOTSUP;
 	}
 
 	if (data_size == hdr->hdr_len) {
-		elog("BTF.ext has no data\n");
+		pr_debug("BTF.ext has no data\n");
 		return -EINVAL;
 	}
 
@@ -685,12 +681,12 @@ void btf_ext__free(struct btf_ext *btf_ext)
 	free(btf_ext);
 }
 
-struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log)
+struct btf_ext *btf_ext__new(__u8 *data, __u32 size)
 {
 	struct btf_ext *btf_ext;
 	int err;
 
-	err = btf_ext_parse_hdr(data, size, err_log);
+	err = btf_ext_parse_hdr(data, size);
 	if (err)
 		return ERR_PTR(err);
 
@@ -698,13 +694,13 @@ struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log)
 	if (!btf_ext)
 		return ERR_PTR(-ENOMEM);
 
-	err = btf_ext_copy_func_info(btf_ext, data, size, err_log);
+	err = btf_ext_copy_func_info(btf_ext, data, size);
 	if (err) {
 		btf_ext__free(btf_ext);
 		return ERR_PTR(err);
 	}
 
-	err = btf_ext_copy_line_info(btf_ext, data, size, err_log);
+	err = btf_ext_copy_line_info(btf_ext, data, size);
 	if (err) {
 		btf_ext__free(btf_ext);
 		return ERR_PTR(err);

tools/lib/bpf/btf.h

@@ -55,11 +55,8 @@ struct btf_ext_header {
 	__u32	line_info_len;
 };
 
-typedef int (*btf_print_fn_t)(const char *, ...)
-	__attribute__((format(printf, 1, 2)));
-
 LIBBPF_API void btf__free(struct btf *btf);
-LIBBPF_API struct btf *btf__new(__u8 *data, __u32 size, btf_print_fn_t err_log);
+LIBBPF_API struct btf *btf__new(__u8 *data, __u32 size);
 LIBBPF_API __s32 btf__find_by_name(const struct btf *btf,
 				   const char *type_name);
 LIBBPF_API const struct btf_type *btf__type_by_id(const struct btf *btf,
@@ -70,7 +67,7 @@ LIBBPF_API int btf__fd(const struct btf *btf);
 LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
 LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf);
 
-struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log);
+struct btf_ext *btf_ext__new(__u8 *data, __u32 size);
 void btf_ext__free(struct btf_ext *btf_ext);
 int btf_ext__reloc_func_info(const struct btf *btf,
 			     const struct btf_ext *btf_ext,

tools/lib/bpf/libbpf.c

@@ -42,6 +42,7 @@
 #include "bpf.h"
 #include "btf.h"
 #include "str_error.h"
+#include "libbpf_util.h"
 
 #ifndef EM_BPF
 #define EM_BPF 247
@@ -53,39 +54,39 @@
 
 #define __printf(a, b)	__attribute__((format(printf, a, b)))
 
-__printf(1, 2)
-static int __base_pr(const char *format, ...)
+__printf(2, 3)
+static int __base_pr(enum libbpf_print_level level, const char *format, ...)
 {
 	va_list args;
 	int err;
 
+	if (level == LIBBPF_DEBUG)
+		return 0;
+
 	va_start(args, format);
 	err = vfprintf(stderr, format, args);
 	va_end(args);
 	return err;
 }
 
-static __printf(1, 2) libbpf_print_fn_t __pr_warning = __base_pr;
-static __printf(1, 2) libbpf_print_fn_t __pr_info = __base_pr;
-static __printf(1, 2) libbpf_print_fn_t __pr_debug;
-
-#define __pr(func, fmt, ...)	\
-do {				\
-	if ((func))		\
-		(func)("libbpf: " fmt, ##__VA_ARGS__); \
-} while (0)
+static __printf(2, 3) libbpf_print_fn_t __libbpf_pr = __base_pr;
 
-#define pr_warning(fmt, ...)	__pr(__pr_warning, fmt, ##__VA_ARGS__)
-#define pr_info(fmt, ...)	__pr(__pr_info, fmt, ##__VA_ARGS__)
-#define pr_debug(fmt, ...)	__pr(__pr_debug, fmt, ##__VA_ARGS__)
+void libbpf_set_print(libbpf_print_fn_t fn)
+{
+	__libbpf_pr = fn;
+}
 
-void libbpf_set_print(libbpf_print_fn_t warn,
-		      libbpf_print_fn_t info,
-		      libbpf_print_fn_t debug)
+__printf(2, 3)
+void libbpf_print(enum libbpf_print_level level, const char *format, ...)
 {
-	__pr_warning = warn;
-	__pr_info = info;
-	__pr_debug = debug;
+	va_list args;
+
+	if (!__libbpf_pr)
+		return;
+
+	va_start(args, format);
+	__libbpf_pr(level, format, args);
+	va_end(args);
 }
 
 #define STRERR_BUFSIZE  128
@@ -839,8 +840,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 		else if (strcmp(name, "maps") == 0)
 			obj->efile.maps_shndx = idx;
 		else if (strcmp(name, BTF_ELF_SEC) == 0) {
-			obj->btf = btf__new(data->d_buf, data->d_size,
-					    __pr_debug);
+			obj->btf = btf__new(data->d_buf, data->d_size);
 			if (IS_ERR(obj->btf)) {
 				pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n",
 					   BTF_ELF_SEC, PTR_ERR(obj->btf));
@@ -915,8 +915,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 				 BTF_EXT_ELF_SEC, BTF_ELF_SEC);
 		} else {
 			obj->btf_ext = btf_ext__new(btf_ext_data->d_buf,
-						    btf_ext_data->d_size,
-						    __pr_debug);
+						    btf_ext_data->d_size);
 			if (IS_ERR(obj->btf_ext)) {
 				pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n",
 					   BTF_EXT_ELF_SEC,

tools/lib/bpf/libbpf.h

@@ -47,17 +47,17 @@ enum libbpf_errno {
 
 LIBBPF_API int libbpf_strerror(int err, char *buf, size_t size);
 
-/*
- * __printf is defined in include/linux/compiler-gcc.h. However,
- * it would be better if libbpf.h didn't depend on Linux header files.
- * So instead of __printf, here we use gcc attribute directly.
- */
-typedef int (*libbpf_print_fn_t)(const char *, ...)
-	__attribute__((format(printf, 1, 2)));
+enum libbpf_print_level {
+        LIBBPF_WARN,
+        LIBBPF_INFO,
+        LIBBPF_DEBUG,
+};
+
+typedef int (*libbpf_print_fn_t)(enum libbpf_print_level level,
+				 const char *, ...)
+	__attribute__((format(printf, 2, 3)));
 
-LIBBPF_API void libbpf_set_print(libbpf_print_fn_t warn,
-				 libbpf_print_fn_t info,
-				 libbpf_print_fn_t debug);
+LIBBPF_API void libbpf_set_print(libbpf_print_fn_t fn);
 
 /* Hide internal to user */
 struct bpf_object;

tools/lib/bpf/libbpf_util.h

+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+/* Copyright (c) 2019 Facebook */
+
+#ifndef __LIBBPF_LIBBPF_UTIL_H
+#define __LIBBPF_LIBBPF_UTIL_H
+
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern void libbpf_print(enum libbpf_print_level level,
+			 const char *format, ...)
+	__attribute__((format(printf, 2, 3)));
+
+#define __pr(level, fmt, ...)	\
+do {				\
+	libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__);	\
+} while (0)
+
+#define pr_warning(fmt, ...)	__pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
+#define pr_info(fmt, ...)	__pr(LIBBPF_INFO, fmt, ##__VA_ARGS__)
+#define pr_debug(fmt, ...)	__pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__)
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif

tools/lib/bpf/test_libbpf.cpp

@@ -8,11 +8,11 @@
 int main(int argc, char *argv[])
 {
     /* libbpf.h */
-    libbpf_set_print(NULL, NULL, NULL);
+    libbpf_set_print(NULL);
 
     /* bpf.h */
     bpf_prog_get_fd_by_id(0);
 
     /* btf.h */
-    btf__new(NULL, 0, NULL);
+    btf__new(NULL, 0);
 }

tools/perf/util/bpf-loader.c

@@ -24,21 +24,17 @@
 #include "llvm-utils.h"
 #include "c++/clang-c.h"
 
-#define DEFINE_PRINT_FN(name, level) \
-static int libbpf_##name(const char *fmt, ...)	\
-{						\
-	va_list args;				\
-	int ret;				\
-						\
-	va_start(args, fmt);			\
-	ret = veprintf(level, verbose, pr_fmt(fmt), args);\
-	va_end(args);				\
-	return ret;				\
-}
+static int libbpf_perf_print(enum libbpf_print_level level __attribute__((unused)),
+			      const char *fmt, ...)
+{
+	va_list args;
+	int ret;
 
-DEFINE_PRINT_FN(warning, 1)
-DEFINE_PRINT_FN(info, 1)
-DEFINE_PRINT_FN(debug, 1)
+	va_start(args, fmt);
+	ret = veprintf(1, verbose, pr_fmt(fmt), args);
+	va_end(args);
+	return ret;
+}
 
 struct bpf_prog_priv {
 	bool is_tp;
@@ -59,9 +55,7 @@ bpf__prepare_load_buffer(void *obj_buf, size_t obj_buf_sz, const char *name)
 	struct bpf_object *obj;
 
 	if (!libbpf_initialized) {
-		libbpf_set_print(libbpf_warning,
-				 libbpf_info,
-				 libbpf_debug);
+		libbpf_set_print(libbpf_perf_print);
 		libbpf_initialized = true;
 	}
 
@@ -79,9 +73,7 @@ struct bpf_object *bpf__prepare_load(const char *filename, bool source)
 	struct bpf_object *obj;
 
 	if (!libbpf_initialized) {
-		libbpf_set_print(libbpf_warning,
-				 libbpf_info,
-				 libbpf_debug);
+		libbpf_set_print(libbpf_perf_print);
 		libbpf_initialized = true;
 	}
 

tools/testing/selftests/bpf/test_btf.c

@@ -54,8 +54,9 @@ static int count_result(int err)
 
 #define __printf(a, b)	__attribute__((format(printf, a, b)))
 
-__printf(1, 2)
-static int __base_pr(const char *format, ...)
+__printf(2, 3)
+static int __base_pr(enum libbpf_print_level level __attribute__((unused)),
+		     const char *format, ...)
 {
 	va_list args;
 	int err;
@@ -5650,7 +5651,7 @@ int main(int argc, char **argv)
 		return err;
 
 	if (args.always_log)
-		libbpf_set_print(__base_pr, __base_pr, __base_pr);
+		libbpf_set_print(__base_pr);
 
 	if (args.raw_test)
 		err |= test_raw();

tools/testing/selftests/bpf/test_libbpf_open.c

@@ -34,23 +34,22 @@ static void usage(char *argv[])
 	printf("\n");
 }
 
-#define DEFINE_PRINT_FN(name, enabled) \
-static int libbpf_##name(const char *fmt, ...)  	\
-{							\
-        va_list args;					\
-        int ret;					\
-							\
-        va_start(args, fmt);				\
-	if (enabled) {					\
-		fprintf(stderr, "[" #name "] ");	\
-		ret = vfprintf(stderr, fmt, args);	\
-	}						\
-        va_end(args);					\
-        return ret;					\
+static bool debug = 0;
+static int libbpf_debug_print(enum libbpf_print_level level,
+			      const char *fmt, ...)
+{
+	va_list args;
+	int ret;
+
+	if (level == LIBBPF_DEBUG && !debug)
+		return 0;
+
+	va_start(args, fmt);
+	fprintf(stderr, "[%d] ", level);
+	ret = vfprintf(stderr, fmt, args);
+	va_end(args);
+	return ret;
 }
-DEFINE_PRINT_FN(warning, 1)
-DEFINE_PRINT_FN(info, 1)
-DEFINE_PRINT_FN(debug, 1)
 
 #define EXIT_FAIL_LIBBPF EXIT_FAILURE
 #define EXIT_FAIL_OPTION 2
@@ -120,15 +119,14 @@ int main(int argc, char **argv)
 	int longindex = 0;
 	int opt;
 
-	libbpf_set_print(libbpf_warning, libbpf_info, NULL);
+	libbpf_set_print(libbpf_debug_print);
 
 	/* Parse commands line args */
 	while ((opt = getopt_long(argc, argv, "hDq",
 				  long_options, &longindex)) != -1) {
 		switch (opt) {
 		case 'D':
-			libbpf_set_print(libbpf_warning, libbpf_info,
-					 libbpf_debug);
+			debug = 1;
 			break;
 		case 'q': /* Use in scripting mode */
 			verbose = 0;

tools/testing/selftests/bpf/test_progs.c

@@ -10,6 +10,7 @@
 #include <string.h>
 #include <assert.h>
 #include <stdlib.h>
+#include <stdarg.h>
 #include <time.h>
 
 #include <linux/types.h>
@@ -1783,6 +1784,21 @@ static void test_task_fd_query_tp(void)
 				   "sys_enter_read");
 }
 
+static int libbpf_debug_print(enum libbpf_print_level level,
+			      const char *format, ...)
+{
+	va_list args;
+	int ret;
+
+	if (level == LIBBPF_DEBUG)
+		return 0;
+
+	va_start(args, format);
+	ret = vfprintf(stderr, format, args);
+	va_end(args);
+	return ret;
+}
+
 static void test_reference_tracking()
 {
 	const char *file = "./test_sk_lookup_kern.o";
@@ -1809,9 +1825,9 @@ static void test_reference_tracking()
 
 		/* Expect verifier failure if test name has 'fail' */
 		if (strstr(title, "fail") != NULL) {
-			libbpf_set_print(NULL, NULL, NULL);
+			libbpf_set_print(NULL);
 			err = !bpf_program__load(prog, "GPL", 0);
-			libbpf_set_print(printf, printf, NULL);
+			libbpf_set_print(libbpf_debug_print);
 		} else {
 			err = bpf_program__load(prog, "GPL", 0);
 		}