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  3. [PATCH bpf-next v3 00/13] bpf: Kernel functions with KF_IMPLICIT_ARGS
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[PATCH bpf-next v3 07/13] bpf: Migrate bpf_wq_set_callback_impl() to KF_IMPLICIT_ARGS

Ihor Solodrai posted 13 patches 2 weeks, 4 days ago
[PATCH bpf-next v3 07/13] bpf: Migrate bpf_wq_set_callback_impl() to KF_IMPLICIT_ARGS
Posted by Ihor Solodrai 2 weeks, 4 days ago 
Implement bpf_wq_set_callback() with an implicit bpf_prog_aux
argument, and remove bpf_wq_set_callback_impl().

Update special kfunc checks in the verifier accordingly.

Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 kernel/bpf/helpers.c                             | 11 +++++------
 kernel/bpf/verifier.c                            | 16 ++++++++--------
 tools/testing/selftests/bpf/bpf_experimental.h   |  5 -----
 .../bpf/progs/verifier_async_cb_context.c        |  4 ++--
 tools/testing/selftests/bpf/progs/wq_failures.c  |  4 ++--
 5 files changed, 17 insertions(+), 23 deletions(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 9eaa4185e0a7..c76a9003b221 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -3120,12 +3120,11 @@ __bpf_kfunc int bpf_wq_start(struct bpf_wq *wq, unsigned int flags)
 	return 0;
 }
 
-__bpf_kfunc int bpf_wq_set_callback_impl(struct bpf_wq *wq,
-					 int (callback_fn)(void *map, int *key, void *value),
-					 unsigned int flags,
-					 void *aux__prog)
+__bpf_kfunc int bpf_wq_set_callback(struct bpf_wq *wq,
+				    int (callback_fn)(void *map, int *key, void *value),
+				    unsigned int flags,
+				    struct bpf_prog_aux *aux)
 {
-	struct bpf_prog_aux *aux = (struct bpf_prog_aux *)aux__prog;
 	struct bpf_async_kern *async = (struct bpf_async_kern *)wq;
 
 	if (flags)
@@ -4488,7 +4487,7 @@ BTF_ID_FLAGS(func, bpf_dynptr_memset)
 BTF_ID_FLAGS(func, bpf_modify_return_test_tp)
 #endif
 BTF_ID_FLAGS(func, bpf_wq_init)
-BTF_ID_FLAGS(func, bpf_wq_set_callback_impl)
+BTF_ID_FLAGS(func, bpf_wq_set_callback, KF_IMPLICIT_ARGS)
 BTF_ID_FLAGS(func, bpf_wq_start)
 BTF_ID_FLAGS(func, bpf_preempt_disable)
 BTF_ID_FLAGS(func, bpf_preempt_enable)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index adc24a2ce5b6..51e8c9f70868 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -520,7 +520,7 @@ static bool is_async_callback_calling_kfunc(u32 btf_id);
 static bool is_callback_calling_kfunc(u32 btf_id);
 static bool is_bpf_throw_kfunc(struct bpf_insn *insn);
 
-static bool is_bpf_wq_set_callback_impl_kfunc(u32 btf_id);
+static bool is_bpf_wq_set_callback_kfunc(u32 btf_id);
 static bool is_task_work_add_kfunc(u32 func_id);
 
 static bool is_sync_callback_calling_function(enum bpf_func_id func_id)
@@ -562,7 +562,7 @@ static bool is_async_cb_sleepable(struct bpf_verifier_env *env, struct bpf_insn
 
 	/* bpf_wq and bpf_task_work callbacks are always sleepable. */
 	if (bpf_pseudo_kfunc_call(insn) && insn->off == 0 &&
-	    (is_bpf_wq_set_callback_impl_kfunc(insn->imm) || is_task_work_add_kfunc(insn->imm)))
+	    (is_bpf_wq_set_callback_kfunc(insn->imm) || is_task_work_add_kfunc(insn->imm)))
 		return true;
 
 	verifier_bug(env, "unhandled async callback in is_async_cb_sleepable");
@@ -12437,7 +12437,7 @@ enum special_kfunc_type {
 	KF_bpf_percpu_obj_new_impl,
 	KF_bpf_percpu_obj_drop_impl,
 	KF_bpf_throw,
-	KF_bpf_wq_set_callback_impl,
+	KF_bpf_wq_set_callback,
 	KF_bpf_preempt_disable,
 	KF_bpf_preempt_enable,
 	KF_bpf_iter_css_task_new,
@@ -12501,7 +12501,7 @@ BTF_ID(func, bpf_dynptr_clone)
 BTF_ID(func, bpf_percpu_obj_new_impl)
 BTF_ID(func, bpf_percpu_obj_drop_impl)
 BTF_ID(func, bpf_throw)
-BTF_ID(func, bpf_wq_set_callback_impl)
+BTF_ID(func, bpf_wq_set_callback)
 BTF_ID(func, bpf_preempt_disable)
 BTF_ID(func, bpf_preempt_enable)
 #ifdef CONFIG_CGROUPS
@@ -12994,7 +12994,7 @@ static bool is_sync_callback_calling_kfunc(u32 btf_id)
 
 static bool is_async_callback_calling_kfunc(u32 btf_id)
 {
-	return btf_id == special_kfunc_list[KF_bpf_wq_set_callback_impl] ||
+	return is_bpf_wq_set_callback_kfunc(btf_id) ||
 	       is_task_work_add_kfunc(btf_id);
 }
 
@@ -13004,9 +13004,9 @@ static bool is_bpf_throw_kfunc(struct bpf_insn *insn)
 	       insn->imm == special_kfunc_list[KF_bpf_throw];
 }
 
-static bool is_bpf_wq_set_callback_impl_kfunc(u32 btf_id)
+static bool is_bpf_wq_set_callback_kfunc(u32 btf_id)
 {
-	return btf_id == special_kfunc_list[KF_bpf_wq_set_callback_impl];
+	return btf_id == special_kfunc_list[KF_bpf_wq_set_callback];
 }
 
 static bool is_callback_calling_kfunc(u32 btf_id)
@@ -14085,7 +14085,7 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 		meta.r0_rdonly = false;
 	}
 
-	if (is_bpf_wq_set_callback_impl_kfunc(meta.func_id)) {
+	if (is_bpf_wq_set_callback_kfunc(meta.func_id)) {
 		err = push_callback_call(env, insn, insn_idx, meta.subprogno,
 					 set_timer_callback_state);
 		if (err) {
diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index 2cd9165c7348..68a49b1f77ae 100644
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -580,11 +580,6 @@ extern void bpf_iter_css_destroy(struct bpf_iter_css *it) __weak __ksym;
 
 extern int bpf_wq_init(struct bpf_wq *wq, void *p__map, unsigned int flags) __weak __ksym;
 extern int bpf_wq_start(struct bpf_wq *wq, unsigned int flags) __weak __ksym;
-extern int bpf_wq_set_callback_impl(struct bpf_wq *wq,
-		int (callback_fn)(void *map, int *key, void *value),
-		unsigned int flags__k, void *aux__ign) __ksym;
-#define bpf_wq_set_callback(timer, cb, flags) \
-	bpf_wq_set_callback_impl(timer, cb, flags, NULL)
 
 struct bpf_iter_kmem_cache;
 extern int bpf_iter_kmem_cache_new(struct bpf_iter_kmem_cache *it) __weak __ksym;
diff --git a/tools/testing/selftests/bpf/progs/verifier_async_cb_context.c b/tools/testing/selftests/bpf/progs/verifier_async_cb_context.c
index 7efa9521105e..5d5e1cd4d51d 100644
--- a/tools/testing/selftests/bpf/progs/verifier_async_cb_context.c
+++ b/tools/testing/selftests/bpf/progs/verifier_async_cb_context.c
@@ -96,7 +96,7 @@ int wq_non_sleepable_prog(void *ctx)
 
 	if (bpf_wq_init(&val->w, &wq_map, 0) != 0)
 		return 0;
-	if (bpf_wq_set_callback_impl(&val->w, wq_cb, 0, NULL) != 0)
+	if (bpf_wq_set_callback(&val->w, wq_cb, 0) != 0)
 		return 0;
 	return 0;
 }
@@ -114,7 +114,7 @@ int wq_sleepable_prog(void *ctx)
 
 	if (bpf_wq_init(&val->w, &wq_map, 0) != 0)
 		return 0;
-	if (bpf_wq_set_callback_impl(&val->w, wq_cb, 0, NULL) != 0)
+	if (bpf_wq_set_callback(&val->w, wq_cb, 0) != 0)
 		return 0;
 	return 0;
 }
diff --git a/tools/testing/selftests/bpf/progs/wq_failures.c b/tools/testing/selftests/bpf/progs/wq_failures.c
index d06f6d40594a..3767f5595bbc 100644
--- a/tools/testing/selftests/bpf/progs/wq_failures.c
+++ b/tools/testing/selftests/bpf/progs/wq_failures.c
@@ -97,7 +97,7 @@ __failure
 /* check that the first argument of bpf_wq_set_callback()
  * is a correct bpf_wq pointer.
  */
-__msg(": (85) call bpf_wq_set_callback_impl#") /* anchor message */
+__msg(": (85) call bpf_wq_set_callback#") /* anchor message */
 __msg("arg#0 doesn't point to a map value")
 long test_wrong_wq_pointer(void *ctx)
 {
@@ -123,7 +123,7 @@ __failure
 /* check that the first argument of bpf_wq_set_callback()
  * is a correct bpf_wq pointer.
  */
-__msg(": (85) call bpf_wq_set_callback_impl#") /* anchor message */
+__msg(": (85) call bpf_wq_set_callback#") /* anchor message */
 __msg("off 1 doesn't point to 'struct bpf_wq' that is at 0")
 long test_wrong_wq_pointer_offset(void *ctx)
 {
-- 
2.52.0
Re: [PATCH bpf-next v3 07/13] bpf: Migrate bpf_wq_set_callback_impl() to KF_IMPLICIT_ARGS
Posted by bot+bpf-ci@kernel.org 2 weeks, 4 days ago 
> diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
> index 2cd9165c7348..68a49b1f77ae 100644
> --- a/tools/testing/selftests/bpf/bpf_experimental.h
> +++ b/tools/testing/selftests/bpf/bpf_experimental.h
> @@ -580,11 +580,6 @@ extern void bpf_iter_css_destroy(struct bpf_iter_css *it) __weak __ksym;
>
>  extern int bpf_wq_init(struct bpf_wq *wq, void *p__map, unsigned int flags) __weak __ksym;
>  extern int bpf_wq_start(struct bpf_wq *wq, unsigned int flags) __weak __ksym;
> -extern int bpf_wq_set_callback_impl(struct bpf_wq *wq,
> -		int (callback_fn)(void *map, int *key, void *value),
> -		unsigned int flags__k, void *aux__ign) __ksym;
> -#define bpf_wq_set_callback(timer, cb, flags) \
> -	bpf_wq_set_callback_impl(timer, cb, flags, NULL)

The old bpf_wq_set_callback_impl declaration and bpf_wq_set_callback macro
are removed here, but there does not appear to be a replacement declaration
for the new bpf_wq_set_callback kfunc.

Test files wq.c and wq_failures.c include bpf_experimental.h but do not
include vmlinux.h. They continue to call bpf_wq_set_callback() after this
change. Without an extern declaration such as:

    extern int bpf_wq_set_callback(struct bpf_wq *wq,
            int (callback_fn)(void *map, int *key, void *value),
            unsigned int flags) __weak __ksym;

should these test files fail to compile due to the missing declaration?
The kfunc_implicit_args.c test (from the earlier commit in this series)
demonstrates that explicit __ksym declarations are needed for kfuncs that
are not obtained from vmlinux.h.

[ ... ]


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/21190053819
Re: [PATCH bpf-next v3 07/13] bpf: Migrate bpf_wq_set_callback_impl() to KF_IMPLICIT_ARGS
Posted by Ihor Solodrai 2 weeks, 4 days ago 
On 1/20/26 2:55 PM, bot+bpf-ci@kernel.org wrote:
>> diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
>> index 2cd9165c7348..68a49b1f77ae 100644
>> --- a/tools/testing/selftests/bpf/bpf_experimental.h
>> +++ b/tools/testing/selftests/bpf/bpf_experimental.h
>> @@ -580,11 +580,6 @@ extern void bpf_iter_css_destroy(struct bpf_iter_css *it) __weak __ksym;
>>
>>  extern int bpf_wq_init(struct bpf_wq *wq, void *p__map, unsigned int flags) __weak __ksym;
>>  extern int bpf_wq_start(struct bpf_wq *wq, unsigned int flags) __weak __ksym;
>> -extern int bpf_wq_set_callback_impl(struct bpf_wq *wq,
>> -		int (callback_fn)(void *map, int *key, void *value),
>> -		unsigned int flags__k, void *aux__ign) __ksym;
>> -#define bpf_wq_set_callback(timer, cb, flags) \
>> -	bpf_wq_set_callback_impl(timer, cb, flags, NULL)
> 
> The old bpf_wq_set_callback_impl declaration and bpf_wq_set_callback macro
> are removed here, but there does not appear to be a replacement declaration
> for the new bpf_wq_set_callback kfunc.
> 
> Test files wq.c and wq_failures.c include bpf_experimental.h but do not
> include vmlinux.h. They continue to call bpf_wq_set_callback() after this

Looks like AI failed to notice, that vmlinux.h is included in
bpf_experimental.h

https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/tree/tools/testing/selftests/bpf/bpf_experimental.h#n4

So the old extern declaration of bpf_wq_set_callback_impl() wasn't
necessary too, although the macro was.


> change. Without an extern declaration such as:
> 
>     extern int bpf_wq_set_callback(struct bpf_wq *wq,
>             int (callback_fn)(void *map, int *key, void *value),
>             unsigned int flags) __weak __ksym;
> 
> should these test files fail to compile due to the missing declaration?
> The kfunc_implicit_args.c test (from the earlier commit in this series)
> demonstrates that explicit __ksym declarations are needed for kfuncs that
> are not obtained from vmlinux.h.
> 
> [ ... ]
> 
> 
> ---
> AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
> See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
> 
> CI run summary: https://github.com/kernel-patches/bpf/actions/runs/21190053819

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