From 4cf23a3c6359556a1cca489cf2b901e2b904c4b0 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 9 Dec 2021 11:38:29 -0800 Subject: libbpf: Fix bpf_prog_load() log_buf logic for log_level 0 To unify libbpf APIs behavior w.r.t. log_buf and log_level, fix bpf_prog_load() to follow the same logic as bpf_btf_load() and high-level bpf_object__load() API will follow in the subsequent patches: - if log_level is 0 and non-NULL log_buf is provided by a user, attempt load operation initially with no log_buf and log_level set; - if successful, we are done, return new FD; - on error, retry the load operation with log_level bumped to 1 and log_buf set; this way verbose logging will be requested only when we are sure that there is a failure, but will be fast in the common/expected success case. Of course, user can still specify log_level > 0 from the very beginning to force log collection. Suggested-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20211209193840.1248570-2-andrii@kernel.org --- tools/lib/bpf/bpf.c | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-) (limited to 'tools/lib/bpf/bpf.c') diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index 4e7836e1a7b5..3dc86342f0a0 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -303,10 +303,6 @@ int bpf_prog_load_v0_6_0(enum bpf_prog_type prog_type, if (log_level && !log_buf) return libbpf_err(-EINVAL); - attr.log_level = log_level; - attr.log_buf = ptr_to_u64(log_buf); - attr.log_size = log_size; - func_info_rec_size = OPTS_GET(opts, func_info_rec_size, 0); func_info = OPTS_GET(opts, func_info, NULL); attr.func_info_rec_size = func_info_rec_size; @@ -321,6 +317,12 @@ int bpf_prog_load_v0_6_0(enum bpf_prog_type prog_type, attr.fd_array = ptr_to_u64(OPTS_GET(opts, fd_array, NULL)); + if (log_level) { + attr.log_buf = ptr_to_u64(log_buf); + attr.log_size = log_size; + attr.log_level = log_level; + } + fd = sys_bpf_prog_load(&attr, sizeof(attr), attempts); if (fd >= 0) return fd; @@ -366,16 +368,17 @@ int bpf_prog_load_v0_6_0(enum bpf_prog_type prog_type, goto done; } - if (log_level || !log_buf) - goto done; + if (log_level == 0 && log_buf) { + /* log_level == 0 with non-NULL log_buf requires retrying on error + * with log_level == 1 and log_buf/log_buf_size set, to get details of + * failure + */ + attr.log_buf = ptr_to_u64(log_buf); + attr.log_size = log_size; + attr.log_level = 1; - /* Try again with log */ - log_buf[0] = 0; - attr.log_buf = ptr_to_u64(log_buf); - attr.log_size = log_size; - attr.log_level = 1; - - fd = sys_bpf_prog_load(&attr, sizeof(attr), attempts); + fd = sys_bpf_prog_load(&attr, sizeof(attr), attempts); + } done: /* free() doesn't affect errno, so we don't need to restore it */ free(finfo); -- cgit v1.2.3-59-g8ed1b