Commit 803370d3 authored by Anton Protopopov's avatar Anton Protopopov Committed by Alexei Starovoitov
Browse files

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: default avatarAnton Protopopov <aspsk@isovalent.com>
Link: https://lore.kernel.org/r/20230706133932.45883-3-aspsk@isovalent.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 25954730

kernel/bpf/map_iter.c

+38 −1
Original line number Diff line number Diff line
@@ -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);