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libbpf: Split feature detectors definitions from cached results

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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>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-22-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko 2024-01-23 18:21:18 -08:00 committed by Alexei Starovoitov
parent 0350f9d99e
commit ea4d587354
1 changed files with 12 additions and 6 deletions
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18
tools/lib/bpf/libbpf.c
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@ -4958,12 +4958,17 @@ 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,
@ -5031,6 +5036,7 @@ 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)
@ -5039,19 +5045,19 @@ 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)