Merge branch 'bpf-add-_impl-suffix-for-kfuncs-with-implicit-args'

Mykyta Yatsenko says:

====================
bpf: Add _impl suffix for kfuncs with implicit args

We have established a pattern of function naming win "_impl" suffix;
those functions accept verifier-provided bpf_prog_aux argument.
Following uniform convention will allow for transparent backwards
compatibility with the upcoming KF_IMPLICIT_ARGS feature. This patch
set aims to fix current deviation from the convention to eliminate
unnecessary backwards incompatibility in the future.

Three kfuncs added in 6.18 don’t follow this *_impl convention and
therefore won’t participate in the new KF_IMPLICIT_ARGS mechanism:
 * bpf_task_work_schedule_resume()
 * bpf_task_work_schedule_signal()
 * bpf_stream_vprintk()

Rename them to align with the implicit-arg flow:
bpf_task_work_schedule_resume() -> bpf_task_work_schedule_resume_impl()
bpf_task_work_schedule_signal() -> bpf_task_work_schedule_signal_impl()
bpf_stream_vprintk() -> bpf_stream_vprintk_impl()

The KF_IMPLICIT_ARGS mechanism is not in tree yet, so callers must
switch to the *_impl names for now. Once the new mechanism lands, the
plain names (without _impl) will be reintroduced.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
Changes in v3:
- Fix commit messages
- Link to v2: https://lore.kernel.org/r/20251104-implv2-v2-0-6dbc35f39f28@meta.com

Changes in v1:
- Split commit into 2
- Rebase on the correct branch
- Link to v1: https://lore.kernel.org/all/20251103232319.122965-1-mykyta.yatsenko5@gmail.com/
====================

Link: https://patch.msgid.link/20251104-implv2-v3-0-4772b9ae0e06@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: Alexei Starovoitov

kernel/bpf/helpers.c

@@ -4169,7 +4169,8 @@ static int bpf_task_work_schedule(struct task_struct *task, struct bpf_task_work
 }
 
 /**
- * bpf_task_work_schedule_signal - Schedule BPF callback using task_work_add with TWA_SIGNAL mode
+ * bpf_task_work_schedule_signal_impl - Schedule BPF callback using task_work_add with TWA_SIGNAL
+ * mode
  * @task: Task struct for which callback should be scheduled
  * @tw: Pointer to struct bpf_task_work in BPF map value for internal bookkeeping
  * @map__map: bpf_map that embeds struct bpf_task_work in the values
@@ -4178,15 +4179,17 @@ static int bpf_task_work_schedule(struct task_struct *task, struct bpf_task_work
  *
  * Return: 0 if task work has been scheduled successfully, negative error code otherwise
  */
-__bpf_kfunc int bpf_task_work_schedule_signal(struct task_struct *task, struct bpf_task_work *tw,
-					      void *map__map, bpf_task_work_callback_t callback,
-					      void *aux__prog)
+__bpf_kfunc int bpf_task_work_schedule_signal_impl(struct task_struct *task,
+						   struct bpf_task_work *tw, void *map__map,
+						   bpf_task_work_callback_t callback,
+						   void *aux__prog)
 {
 	return bpf_task_work_schedule(task, tw, map__map, callback, aux__prog, TWA_SIGNAL);
 }
 
 /**
- * bpf_task_work_schedule_resume - Schedule BPF callback using task_work_add with TWA_RESUME mode
+ * bpf_task_work_schedule_resume_impl - Schedule BPF callback using task_work_add with TWA_RESUME
+ * mode
  * @task: Task struct for which callback should be scheduled
  * @tw: Pointer to struct bpf_task_work in BPF map value for internal bookkeeping
  * @map__map: bpf_map that embeds struct bpf_task_work in the values
@@ -4195,9 +4198,10 @@ __bpf_kfunc int bpf_task_work_schedule_signal(struct task_struct *task, struct b
  *
  * Return: 0 if task work has been scheduled successfully, negative error code otherwise
  */
-__bpf_kfunc int bpf_task_work_schedule_resume(struct task_struct *task, struct bpf_task_work *tw,
-					      void *map__map, bpf_task_work_callback_t callback,
-					      void *aux__prog)
+__bpf_kfunc int bpf_task_work_schedule_resume_impl(struct task_struct *task,
+						   struct bpf_task_work *tw, void *map__map,
+						   bpf_task_work_callback_t callback,
+						   void *aux__prog)
 {
 	return bpf_task_work_schedule(task, tw, map__map, callback, aux__prog, TWA_RESUME);
 }
@@ -4376,9 +4380,9 @@ BTF_ID_FLAGS(func, bpf_strnstr);
 #if defined(CONFIG_BPF_LSM) && defined(CONFIG_CGROUPS)
 BTF_ID_FLAGS(func, bpf_cgroup_read_xattr, KF_RCU)
 #endif
-BTF_ID_FLAGS(func, bpf_stream_vprintk, KF_TRUSTED_ARGS)
-BTF_ID_FLAGS(func, bpf_task_work_schedule_signal, KF_TRUSTED_ARGS)
-BTF_ID_FLAGS(func, bpf_task_work_schedule_resume, KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_stream_vprintk_impl, KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_task_work_schedule_signal_impl, KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_task_work_schedule_resume_impl, KF_TRUSTED_ARGS)
 BTF_KFUNCS_END(common_btf_ids)
 
 static const struct btf_kfunc_id_set common_kfunc_set = {

kernel/bpf/stream.c

@@ -355,7 +355,8 @@ __bpf_kfunc_start_defs();
  * Avoid using enum bpf_stream_id so that kfunc users don't have to pull in the
  * enum in headers.
  */
-__bpf_kfunc int bpf_stream_vprintk(int stream_id, const char *fmt__str, const void *args, u32 len__sz, void *aux__prog)
+__bpf_kfunc int bpf_stream_vprintk_impl(int stream_id, const char *fmt__str, const void *args,
+					u32 len__sz, void *aux__prog)
 {
 	struct bpf_bprintf_data data = {
 		.get_bin_args	= true,

kernel/bpf/verifier.c

@@ -12259,8 +12259,8 @@ enum special_kfunc_type {
 	KF_bpf_res_spin_lock_irqsave,
 	KF_bpf_res_spin_unlock_irqrestore,
 	KF___bpf_trap,
-	KF_bpf_task_work_schedule_signal,
-	KF_bpf_task_work_schedule_resume,
+	KF_bpf_task_work_schedule_signal_impl,
+	KF_bpf_task_work_schedule_resume_impl,
 };
 
 BTF_ID_LIST(special_kfunc_list)
@@ -12331,13 +12331,13 @@ BTF_ID(func, bpf_res_spin_unlock)
 BTF_ID(func, bpf_res_spin_lock_irqsave)
 BTF_ID(func, bpf_res_spin_unlock_irqrestore)
 BTF_ID(func, __bpf_trap)
-BTF_ID(func, bpf_task_work_schedule_signal)
-BTF_ID(func, bpf_task_work_schedule_resume)
+BTF_ID(func, bpf_task_work_schedule_signal_impl)
+BTF_ID(func, bpf_task_work_schedule_resume_impl)
 
 static bool is_task_work_add_kfunc(u32 func_id)
 {
-	return func_id == special_kfunc_list[KF_bpf_task_work_schedule_signal] ||
-	       func_id == special_kfunc_list[KF_bpf_task_work_schedule_resume];
+	return func_id == special_kfunc_list[KF_bpf_task_work_schedule_signal_impl] ||
+	       func_id == special_kfunc_list[KF_bpf_task_work_schedule_resume_impl];
 }
 
 static bool is_kfunc_ret_null(struct bpf_kfunc_call_arg_meta *meta)

tools/bpf/bpftool/Documentation/bpftool-prog.rst

@@ -182,7 +182,7 @@ bpftool prog tracelog
 
 bpftool prog tracelog { stdout | stderr } *PROG*
     Dump the BPF stream of the program. BPF programs can write to these streams
-    at runtime with the **bpf_stream_vprintk**\ () kfunc. The kernel may write
+    at runtime with the **bpf_stream_vprintk_impl**\ () kfunc. The kernel may write
     error messages to the standard error stream. This facility should be used
     only for debugging purposes.
 

tools/lib/bpf/bpf_helpers.h

@@ -315,20 +315,20 @@ enum libbpf_tristate {
 			  ___param, sizeof(___param));		\
 })
 
-extern int bpf_stream_vprintk(int stream_id, const char *fmt__str, const void *args,
-			      __u32 len__sz, void *aux__prog) __weak __ksym;
-
-#define bpf_stream_printk(stream_id, fmt, args...)				\
-({										\
-	static const char ___fmt[] = fmt;					\
-	unsigned long long ___param[___bpf_narg(args)];				\
-										\
-	_Pragma("GCC diagnostic push")						\
-	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")			\
-	___bpf_fill(___param, args);						\
-	_Pragma("GCC diagnostic pop")						\
-										\
-	bpf_stream_vprintk(stream_id, ___fmt, ___param, sizeof(___param), NULL);\
+extern int bpf_stream_vprintk_impl(int stream_id, const char *fmt__str, const void *args,
+				   __u32 len__sz, void *aux__prog) __weak __ksym;
+
+#define bpf_stream_printk(stream_id, fmt, args...)					\
+({											\
+	static const char ___fmt[] = fmt;						\
+	unsigned long long ___param[___bpf_narg(args)];					\
+											\
+	_Pragma("GCC diagnostic push")							\
+	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")				\
+	___bpf_fill(___param, args);							\
+	_Pragma("GCC diagnostic pop")							\
+											\
+	bpf_stream_vprintk_impl(stream_id, ___fmt, ___param, sizeof(___param), NULL);	\
 })
 
 /* Use __bpf_printk when bpf_printk call has 3 or fewer fmt args

tools/testing/selftests/bpf/progs/stream_fail.c

@@ -10,23 +10,23 @@ SEC("syscall")
 __failure __msg("Possibly NULL pointer passed")
 int stream_vprintk_null_arg(void *ctx)
 {
-	bpf_stream_vprintk(BPF_STDOUT, "", NULL, 0, NULL);
+	bpf_stream_vprintk_impl(BPF_STDOUT, "", NULL, 0, NULL);
 	return 0;
 }
 
 SEC("syscall")
 __failure __msg("R3 type=scalar expected=")
 int stream_vprintk_scalar_arg(void *ctx)
 {
-	bpf_stream_vprintk(BPF_STDOUT, "", (void *)46, 0, NULL);
+	bpf_stream_vprintk_impl(BPF_STDOUT, "", (void *)46, 0, NULL);
 	return 0;
 }
 
 SEC("syscall")
 __failure __msg("arg#1 doesn't point to a const string")
 int stream_vprintk_string_arg(void *ctx)
 {
-	bpf_stream_vprintk(BPF_STDOUT, ctx, NULL, 0, NULL);
+	bpf_stream_vprintk_impl(BPF_STDOUT, ctx, NULL, 0, NULL);
 	return 0;
 }
 

tools/testing/selftests/bpf/progs/task_work.c

@@ -66,7 +66,7 @@ int oncpu_hash_map(struct pt_regs *args)
 	if (!work)
 		return 0;
 
-	bpf_task_work_schedule_resume(task, &work->tw, &hmap, process_work, NULL);
+	bpf_task_work_schedule_resume_impl(task, &work->tw, &hmap, process_work, NULL);
 	return 0;
 }
 
@@ -80,7 +80,7 @@ int oncpu_array_map(struct pt_regs *args)
 	work = bpf_map_lookup_elem(&arrmap, &key);
 	if (!work)
 		return 0;
-	bpf_task_work_schedule_signal(task, &work->tw, &arrmap, process_work, NULL);
+	bpf_task_work_schedule_signal_impl(task, &work->tw, &arrmap, process_work, NULL);
 	return 0;
 }
 
@@ -102,6 +102,6 @@ int oncpu_lru_map(struct pt_regs *args)
 	work = bpf_map_lookup_elem(&lrumap, &key);
 	if (!work || work->data[0])
 		return 0;
-	bpf_task_work_schedule_resume(task, &work->tw, &lrumap, process_work, NULL);
+	bpf_task_work_schedule_resume_impl(task, &work->tw, &lrumap, process_work, NULL);
 	return 0;
 }

tools/testing/selftests/bpf/progs/task_work_fail.c

@@ -53,7 +53,7 @@ int mismatch_map(struct pt_regs *args)
 	work = bpf_map_lookup_elem(&arrmap, &key);
 	if (!work)
 		return 0;
-	bpf_task_work_schedule_resume(task, &work->tw, &hmap, process_work, NULL);
+	bpf_task_work_schedule_resume_impl(task, &work->tw, &hmap, process_work, NULL);
 	return 0;
 }
 
@@ -65,7 +65,7 @@ int no_map_task_work(struct pt_regs *args)
 	struct bpf_task_work tw;
 
 	task = bpf_get_current_task_btf();
-	bpf_task_work_schedule_resume(task, &tw, &hmap, process_work, NULL);
+	bpf_task_work_schedule_resume_impl(task, &tw, &hmap, process_work, NULL);
 	return 0;
 }
 
@@ -76,7 +76,7 @@ int task_work_null(struct pt_regs *args)
 	struct task_struct *task;
 
 	task = bpf_get_current_task_btf();
-	bpf_task_work_schedule_resume(task, NULL, &hmap, process_work, NULL);
+	bpf_task_work_schedule_resume_impl(task, NULL, &hmap, process_work, NULL);
 	return 0;
 }
 
@@ -91,6 +91,6 @@ int map_null(struct pt_regs *args)
 	work = bpf_map_lookup_elem(&arrmap, &key);
 	if (!work)
 		return 0;
-	bpf_task_work_schedule_resume(task, &work->tw, NULL, process_work, NULL);
+	bpf_task_work_schedule_resume_impl(task, &work->tw, NULL, process_work, NULL);
 	return 0;
 }

tools/testing/selftests/bpf/progs/task_work_stress.c

@@ -51,8 +51,8 @@ int schedule_task_work(void *ctx)
 		if (!work)
 			return 0;
 	}
-	err = bpf_task_work_schedule_signal(bpf_get_current_task_btf(), &work->tw, &hmap,
-					    process_work, NULL);
+	err = bpf_task_work_schedule_signal_impl(bpf_get_current_task_btf(), &work->tw, &hmap,
+						 process_work, NULL);
 	if (err)
 		__sync_fetch_and_add(&schedule_error, 1);
 	else