[PATCH bpf-next v4 2/3] tools/bpf: print out btf log at LIBBPF_WARN level

[Yonghong Song]

Currently, the btf log is allocated and printed out in case
of error at LIBBPF_DEBUG level.
Such logs from kernel are very important for debugging.
For example, bpf syscall BPF_PROG_LOAD command can get
verifier logs back to user space. In function load_program()
of libbpf.c, the log buffer is allocated unconditionally
and printed out at pr_warning() level.

Let us do the similar thing here for btf. Allocate buffer
unconditionally and print out error logs at pr_warning() level.
This can reduce one global function and
optimize for common situations where pr_warning()
is activated either by default or by user supplied
debug output function.

Signed-off-by: Yonghong Song <y...@fb.com>
---
 tools/lib/bpf/btf.c         | 19 +++++++++----------
 tools/lib/bpf/libbpf.c      | 10 ----------
 tools/lib/bpf/libbpf_util.h |  2 --
 3 files changed, 9 insertions(+), 22 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 93e792b82242..51a0db05bf80 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -377,16 +377,15 @@ struct btf *btf__new(__u8 *data, __u32 size)
 
        btf->fd = -1;
 
-       if (libbpf_print_level_available(LIBBPF_DEBUG)) {
-               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;
@@ -401,9 +400,9 @@ struct btf *btf__new(__u8 *data, __u32 size)
 
        if (btf->fd == -1) {
                err = -errno;
-               pr_debug("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)
-                       pr_debug("%s\n", log_buf);
+                       pr_warning("%s\n", log_buf);
                goto done;
        }
 
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index eeba77b695ad..0354af03b038 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -98,16 +98,6 @@ void libbpf_print(enum libbpf_print_level level, const char 
*format, ...)
        va_end(args);
 }
 
-bool libbpf_print_level_available(enum libbpf_print_level level)
-{
-       if (level == LIBBPF_WARN)
-               return !!__pr_warning;
-       else if (level == LIBBPF_INFO)
-               return !!__pr_info;
-       else
-               return !!__pr_debug;
-}
-
 #define STRERR_BUFSIZE  128
 
 #define CHECK_ERR(action, err, out) do {       \
diff --git a/tools/lib/bpf/libbpf_util.h b/tools/lib/bpf/libbpf_util.h
index 0fdc3b1d0e33..81ecda0cb9c9 100644
--- a/tools/lib/bpf/libbpf_util.h
+++ b/tools/lib/bpf/libbpf_util.h
@@ -14,8 +14,6 @@ extern void libbpf_print(enum libbpf_print_level level,
                         const char *format, ...)
        __attribute__((format(printf, 2, 3)));
 
-extern bool libbpf_print_level_available(enum libbpf_print_level level);
-
 #define __pr(level, fmt, ...)  \
 do {                           \
        libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__);     \
-- 
2.17.1