Merge branch 'libbpf: error reporting changes for v1.0'

Andrii Nakryiko says:

====================

Implement error reporting changes discussed in "Libbpf: the road to v1.0"
([0]) document.

Libbpf gets a new API, libbpf_set_strict_mode() which accepts a set of flags
that turn on a set of libbpf 1.0 changes, that might be potentially breaking.
It's possible to opt-in into all current and future 1.0 features by specifying
LIBBPF_STRICT_ALL flag.

When some of the 1.0 "features" are requested, libbpf APIs might behave
differently. In this patch set a first set of changes are implemented, all
related to the way libbpf returns errors. See individual patches for details.

Patch #1 adds a no-op libbpf_set_strict_mode() functionality to enable
updating selftests.

Patch #2 gets rid of all the bad code patterns that will break in libbpf 1.0
(exact -1 comparison for low-level APIs, direct IS_ERR() macro usage to check
pointer-returning APIs for error, etc). These changes make selftest work in
both legacy and 1.0 libbpf modes. Selftests also opt-in into 100% libbpf 1.0
mode to automatically gain all the subsequent changes, which will come in
follow up patches.

Patch #3 streamlines error reporting for low-level APIs wrapping bpf() syscall.

Patch #4 streamlines errors for all the rest APIs.

Patch #5 ensures that BPF skeletons propagate errors properly as well, as
currently on error some APIs will return NULL with no way of checking exact
error code.

  [0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY

v1->v2:
  - move libbpf_set_strict_mode() implementation to patch #1, where it belongs
    (Alexei);
  - add acks, slight rewording of commit messages.
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 9 insertions, 9 deletions

diff --git a/tools/lib/bpf/bpf_prog_linfo.c b/tools/lib/bpf/bpf_prog_linfo.c
index 3ed1a27b5f7c..5c503096ef43 100644
--- a/tools/lib/bpf/bpf_prog_linfo.c
+++ b/tools/lib/bpf/bpf_prog_linfo.c
@@ -106,7 +106,7 @@ struct bpf_prog_linfo *bpf_prog_linfo__new(const struct bpf_prog_info *info)
 	nr_linfo = info->nr_line_info;
 
 	if (!nr_linfo)
-		return NULL;
+		return errno = EINVAL, NULL;
 
 	/*
 	 * The min size that bpf_prog_linfo has to access for
@@ -114,11 +114,11 @@ struct bpf_prog_linfo *bpf_prog_linfo__new(const struct bpf_prog_info *info)
 	 */
 	if (info->line_info_rec_size <
 	    offsetof(struct bpf_line_info, file_name_off))
-		return NULL;
+		return errno = EINVAL, NULL;
 
 	prog_linfo = calloc(1, sizeof(*prog_linfo));
 	if (!prog_linfo)
-		return NULL;
+		return errno = ENOMEM, NULL;
 
 	/* Copy xlated line_info */
 	prog_linfo->nr_linfo = nr_linfo;
@@ -174,7 +174,7 @@ struct bpf_prog_linfo *bpf_prog_linfo__new(const struct bpf_prog_info *info)
 
 err_free:
 	bpf_prog_linfo__free(prog_linfo);
-	return NULL;
+	return errno = EINVAL, NULL;
 }
 
 const struct bpf_line_info *
@@ -186,11 +186,11 @@ bpf_prog_linfo__lfind_addr_func(const struct bpf_prog_linfo *prog_linfo,
 	const __u64 *jited_linfo;
 
 	if (func_idx >= prog_linfo->nr_jited_func)
-		return NULL;
+		return errno = ENOENT, NULL;
 
 	nr_linfo = prog_linfo->nr_jited_linfo_per_func[func_idx];
 	if (nr_skip >= nr_linfo)
-		return NULL;
+		return errno = ENOENT, NULL;
 
 	start = prog_linfo->jited_linfo_func_idx[func_idx] + nr_skip;
 	jited_rec_size = prog_linfo->jited_rec_size;
@@ -198,7 +198,7 @@ bpf_prog_linfo__lfind_addr_func(const struct bpf_prog_linfo *prog_linfo,
 		(start * jited_rec_size);
 	jited_linfo = raw_jited_linfo;
 	if (addr < *jited_linfo)
-		return NULL;
+		return errno = ENOENT, NULL;
 
 	nr_linfo -= nr_skip;
 	rec_size = prog_linfo->rec_size;
@@ -225,13 +225,13 @@ bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo,
 
 	nr_linfo = prog_linfo->nr_linfo;
 	if (nr_skip >= nr_linfo)
-		return NULL;
+		return errno = ENOENT, NULL;
 
 	rec_size = prog_linfo->rec_size;
 	raw_linfo = prog_linfo->raw_linfo + (nr_skip * rec_size);
 	linfo = raw_linfo;
 	if (insn_off < linfo->insn_off)
-		return NULL;
+		return errno = ENOENT, NULL;
 
 	nr_linfo -= nr_skip;
 	for (i = 0; i < nr_linfo; i++) {