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bpf: add a new kfunc to return current bpf_map elements count 

A bpf_map_sum_elem_count kfunc was added to simplify getting the sum of the map
per-cpu element counters. If a map doesn't implement the counter, then the
function will always return 0.

Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Link: https://lore.kernel.org/r/20230706133932.45883-3-aspsk@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Anton Protopopov 2023-07-06 13:39:29 +00:00 committed by Alexei Starovoitov
parent 2595473046
commit 803370d3d3
1 changed files with 38 additions and 1 deletions
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39
kernel/bpf/map_iter.c
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@ -93,7 +93,7 @@ static struct bpf_iter_reg bpf_map_reg_info = {
.ctx_arg_info_size = 1,
.ctx_arg_info = {
{ offsetof(struct bpf_iter__bpf_map, map),
PTR_TO_BTF_ID_OR_NULL },
PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },
},
.seq_info = &bpf_map_seq_info,
};
@ -193,3 +193,40 @@ static int __init bpf_map_iter_init(void)
}
late_initcall(bpf_map_iter_init);
__diag_push();
__diag_ignore_all("-Wmissing-prototypes",
"Global functions as their definitions will be in vmlinux BTF");
__bpf_kfunc s64 bpf_map_sum_elem_count(struct bpf_map *map)
{
s64 *pcount;
s64 ret = 0;
int cpu;
if (!map || !map->elem_count)
return 0;
for_each_possible_cpu(cpu) {
pcount = per_cpu_ptr(map->elem_count, cpu);
ret += READ_ONCE(*pcount);
}
return ret;
}
__diag_pop();
BTF_SET8_START(bpf_map_iter_kfunc_ids)
BTF_ID_FLAGS(func, bpf_map_sum_elem_count, KF_TRUSTED_ARGS)
BTF_SET8_END(bpf_map_iter_kfunc_ids)
static const struct btf_kfunc_id_set bpf_map_iter_kfunc_set = {
.owner = THIS_MODULE,
.set = &bpf_map_iter_kfunc_ids,
};
static int init_subsystem(void)
{
return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_map_iter_kfunc_set);
}
late_initcall(init_subsystem);