[PATCH bpf-next 2/8] libbpf: split feature detectors definitions from cached results
From: Andrii Nakryiko <andrii@kernel.org>
Date: 2023-12-07 18:54:58
Also in:
bpf, linux-fsdevel, netdev
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [library] (libbpf), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
Split a list of supported feature detectors with their corresponding callbacks from actual cached supported/missing values. This will allow to have more flexible per-token or per-object feature detectors in subsequent refactorings. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> --- tools/lib/bpf/libbpf.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ea9b8158c20d..a6b8d6f70918 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c@@ -4988,12 +4988,17 @@ enum kern_feature_result { FEAT_MISSING = 2, }; +struct kern_feature_cache { + enum kern_feature_result res[__FEAT_CNT]; +}; + typedef int (*feature_probe_fn)(void); +static struct kern_feature_cache feature_cache; + static struct kern_feature_desc { const char *desc; feature_probe_fn probe; - enum kern_feature_result res; } feature_probes[__FEAT_CNT] = { [FEAT_PROG_NAME] = { "BPF program name", probe_kern_prog_name,
@@ -5061,6 +5066,7 @@ static struct kern_feature_desc { bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id) { struct kern_feature_desc *feat = &feature_probes[feat_id]; + struct kern_feature_cache *cache = &feature_cache; int ret; if (obj && obj->gen_loader)
@@ -5069,19 +5075,19 @@ bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id) */ return true; - if (READ_ONCE(feat->res) == FEAT_UNKNOWN) { + if (READ_ONCE(cache->res[feat_id]) == FEAT_UNKNOWN) { ret = feat->probe(); if (ret > 0) { - WRITE_ONCE(feat->res, FEAT_SUPPORTED); + WRITE_ONCE(cache->res[feat_id], FEAT_SUPPORTED); } else if (ret == 0) { - WRITE_ONCE(feat->res, FEAT_MISSING); + WRITE_ONCE(cache->res[feat_id], FEAT_MISSING); } else { pr_warn("Detection of kernel %s support failed: %d\n", feat->desc, ret); - WRITE_ONCE(feat->res, FEAT_MISSING); + WRITE_ONCE(cache->res[feat_id], FEAT_MISSING); } } - return READ_ONCE(feat->res) == FEAT_SUPPORTED; + return READ_ONCE(cache->res[feat_id]) == FEAT_SUPPORTED; } static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd)
--
2.34.1