Commit 3b413041 authored Jan 13, 2020 by Martin KaFai Lau Committed by Alexei Starovoitov Jan 14, 2020

bpf: Fix seq_show for BPF_MAP_TYPE_STRUCT_OPS



Instead of using bpf_struct_ops_map_lookup_elem() which is
not implemented, bpf_struct_ops_map_seq_show_elem() should
also use bpf_struct_ops_map_sys_lookup_elem() which does
an inplace update to the value.  The change allocates
a value to pass to bpf_struct_ops_map_sys_lookup_elem().

[root@arch-fb-vm1 bpf]# cat /sys/fs/bpf/dctcp
{{{1}},BPF_STRUCT_OPS_STATE_INUSE,{{00000000df93eebc,00000000df93eebc},0,2, ...

Fixes: 85d33df3 ("bpf: Introduce BPF_MAP_TYPE_STRUCT_OPS")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200114072647.3188298-1-kafai@fb.com

parent 6dd42aa1

kernel/bpf/bpf_struct_ops.c

+10 −4

Original line number	Diff line number	Diff line
		@@ -496,16 +496,22 @@ static void bpf_struct_ops_map_seq_show_elem(struct bpf_map map, void key,
		struct seq_file *m)
		{
		void *value;
		int err;

		value = bpf_struct_ops_map_lookup_elem(map, key);
		value = kmalloc(map->value_size, GFP_USER \| __GFP_NOWARN);
		if (!value)
		return;

		err = bpf_struct_ops_map_sys_lookup_elem(map, key, value);
		if (!err) {
		btf_type_seq_show(btf_vmlinux, map->btf_vmlinux_value_type_id,
		value, m);
		seq_puts(m, "\n");
		}

		kfree(value);
		}

		static void bpf_struct_ops_map_free(struct bpf_map *map)
		{
		struct bpf_struct_ops_map st_map = (struct bpf_struct_ops_map )map;

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