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, 13 insertions, 13 deletions

diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c
index 1d80ad4e0de8..8bc117bcc7bc 100644
--- a/tools/lib/bpf/ringbuf.c
+++ b/tools/lib/bpf/ringbuf.c
@@ -69,23 +69,23 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd,
 		err = -errno;
 		pr_warn("ringbuf: failed to get map info for fd=%d: %d\n",
 			map_fd, err);
-		return err;
+		return libbpf_err(err);
 	}
 
 	if (info.type != BPF_MAP_TYPE_RINGBUF) {
 		pr_warn("ringbuf: map fd=%d is not BPF_MAP_TYPE_RINGBUF\n",
 			map_fd);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	tmp = libbpf_reallocarray(rb->rings, rb->ring_cnt + 1, sizeof(*rb->rings));
 	if (!tmp)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 	rb->rings = tmp;
 
 	tmp = libbpf_reallocarray(rb->events, rb->ring_cnt + 1, sizeof(*rb->events));
 	if (!tmp)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 	rb->events = tmp;
 
 	r = &rb->rings[rb->ring_cnt];
@@ -103,7 +103,7 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd,
 		err = -errno;
 		pr_warn("ringbuf: failed to mmap consumer page for map fd=%d: %d\n",
 			map_fd, err);
-		return err;
+		return libbpf_err(err);
 	}
 	r->consumer_pos = tmp;
 
@@ -118,7 +118,7 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd,
 		ringbuf_unmap_ring(rb, r);
 		pr_warn("ringbuf: failed to mmap data pages for map fd=%d: %d\n",
 			map_fd, err);
-		return err;
+		return libbpf_err(err);
 	}
 	r->producer_pos = tmp;
 	r->data = tmp + rb->page_size;
@@ -133,7 +133,7 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd,
 		ringbuf_unmap_ring(rb, r);
 		pr_warn("ringbuf: failed to epoll add map fd=%d: %d\n",
 			map_fd, err);
-		return err;
+		return libbpf_err(err);
 	}
 
 	rb->ring_cnt++;
@@ -165,11 +165,11 @@ ring_buffer__new(int map_fd, ring_buffer_sample_fn sample_cb, void *ctx,
 	int err;
 
 	if (!OPTS_VALID(opts, ring_buffer_opts))
-		return NULL;
+		return errno = EINVAL, NULL;
 
 	rb = calloc(1, sizeof(*rb));
 	if (!rb)
-		return NULL;
+		return errno = ENOMEM, NULL;
 
 	rb->page_size = getpagesize();
 
@@ -188,7 +188,7 @@ ring_buffer__new(int map_fd, ring_buffer_sample_fn sample_cb, void *ctx,
 
 err_out:
 	ring_buffer__free(rb);
-	return NULL;
+	return errno = -err, NULL;
 }
 
 static inline int roundup_len(__u32 len)
@@ -260,7 +260,7 @@ int ring_buffer__consume(struct ring_buffer *rb)
 
 		err = ringbuf_process_ring(ring);
 		if (err < 0)
-			return err;
+			return libbpf_err(err);
 		res += err;
 	}
 	if (res > INT_MAX)
@@ -279,7 +279,7 @@ int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms)
 
 	cnt = epoll_wait(rb->epoll_fd, rb->events, rb->ring_cnt, timeout_ms);
 	if (cnt < 0)
-		return -errno;
+		return libbpf_err(-errno);
 
 	for (i = 0; i < cnt; i++) {
 		__u32 ring_id = rb->events[i].data.fd;
@@ -287,7 +287,7 @@ int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms)
 
 		err = ringbuf_process_ring(ring);
 		if (err < 0)
-			return err;
+			return libbpf_err(err);
 		res += err;
 	}
 	if (res > INT_MAX)