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bpf: Always raise reference in btf_get_module_btf
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Align it with helpers like bpf_find_btf_id, so all functions returning
BTF in out parameter follow the same rule of raising reference
consistently, regardless of module or vmlinux BTF.

Adjust existing callers to handle the change accordinly.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220317115957.3193097-10-memxor@gmail.com
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kkdwivedi authored and Alexei Starovoitov committed Mar 19, 2022
1 parent edc3ec0 commit 9492450
Showing 1 changed file with 11 additions and 10 deletions.
21 changes: 11 additions & 10 deletions kernel/bpf/btf.c
Original file line number Diff line number Diff line change
Expand Up @@ -6572,20 +6572,23 @@ struct module *btf_try_get_module(const struct btf *btf)
return res;
}

/* Returns struct btf corresponding to the struct module
*
* This function can return NULL or ERR_PTR. Note that caller must
* release reference for struct btf iff btf_is_module is true.
/* Returns struct btf corresponding to the struct module.
* This function can return NULL or ERR_PTR.
*/
static struct btf *btf_get_module_btf(const struct module *module)
{
struct btf *btf = NULL;
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
struct btf_module *btf_mod, *tmp;
#endif
struct btf *btf = NULL;

if (!module) {
btf = bpf_get_btf_vmlinux();
if (!IS_ERR(btf))
btf_get(btf);
return btf;
}

if (!module)
return bpf_get_btf_vmlinux();
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
mutex_lock(&btf_module_mutex);
list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
Expand Down Expand Up @@ -6823,9 +6826,7 @@ int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,

hook = bpf_prog_type_to_kfunc_hook(prog_type);
ret = btf_populate_kfunc_set(btf, hook, kset);
/* reference is only taken for module BTF */
if (btf_is_module(btf))
btf_put(btf);
btf_put(btf);
return ret;
}
EXPORT_SYMBOL_GPL(register_btf_kfunc_id_set);
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