diff mbox series

[1/2,v2] bpf: hide unused bpf_patch_call_args

Message ID 20230523194930.2116181-1-arnd@kernel.org
State New
Headers
Series [1/2,v2] bpf: hide unused bpf_patch_call_args |

Commit Message

Arnd Bergmann May 23, 2023, 7:43 p.m. UTC 
  From: Arnd Bergmann <arnd@arndb.de>

This function has no callers and no declaration when CONFIG_BPF_JIT_ALWAYS_ON
is enabled:

kernel/bpf/core.c:2075:6: error: no previous prototype for 'bpf_patch_call_args' [-Werror=missing-prototypes]

Hide the definition as well.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: change indentation to align arguments better. Still not great
as the line is just too long
---
 kernel/bpf/core.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

Comments

Yonghong Song May 24, 2023, 3:05 a.m. UTC | #1 
On 5/23/23 12:43 PM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> This function has no callers and no declaration when CONFIG_BPF_JIT_ALWAYS_ON
> is enabled:
> 
> kernel/bpf/core.c:2075:6: error: no previous prototype for 'bpf_patch_call_args' [-Werror=missing-prototypes]

If CONFIG_BPF_JIT_ALWAYS_ON is enabled, the definition of
bpf_patch_call_args should be invisible. Maybe I missed something.
Could you list *ALL& bpf related config options in your setup
so people can reproduce you above error messages?

> 
> Hide the definition as well.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> v2: change indentation to align arguments better. Still not great
> as the line is just too long
> ---
>   kernel/bpf/core.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index 7421487422d4..0926714641eb 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -2064,14 +2064,16 @@ EVAL4(PROG_NAME_LIST, 416, 448, 480, 512)
>   };
>   #undef PROG_NAME_LIST
>   #define PROG_NAME_LIST(stack_size) PROG_NAME_ARGS(stack_size),
> -static u64 (*interpreters_args[])(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5,
> -				  const struct bpf_insn *insn) = {
> +static __maybe_unused
> +u64 (*interpreters_args[])(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5,
> +			   const struct bpf_insn *insn) = {
>   EVAL6(PROG_NAME_LIST, 32, 64, 96, 128, 160, 192)
>   EVAL6(PROG_NAME_LIST, 224, 256, 288, 320, 352, 384)
>   EVAL4(PROG_NAME_LIST, 416, 448, 480, 512)
>   };
>   #undef PROG_NAME_LIST
>   
> +#ifdef CONFIG_BPF_SYSCALL
>   void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth)
>   {
>   	stack_depth = max_t(u32, stack_depth, 1);
> @@ -2080,6 +2082,7 @@ void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth)
>   		__bpf_call_base_args;
>   	insn->code = BPF_JMP | BPF_CALL_ARGS;
>   }
> +#endif
>   
>   #else
>   static unsigned int __bpf_prog_ret0_warn(const void *ctx,
Arnd Bergmann May 24, 2023, 1:23 p.m. UTC | #2 
On Wed, May 24, 2023, at 05:05, Yonghong Song wrote:
> On 5/23/23 12:43 PM, Arnd Bergmann wrote:
>> From: Arnd Bergmann <arnd@arndb.de>
>> 
>> This function has no callers and no declaration when CONFIG_BPF_JIT_ALWAYS_ON
>> is enabled:
>> 
>> kernel/bpf/core.c:2075:6: error: no previous prototype for 'bpf_patch_call_args' [-Werror=missing-prototypes]
>
> If CONFIG_BPF_JIT_ALWAYS_ON is enabled, the definition of
> bpf_patch_call_args should be invisible. Maybe I missed something.
> Could you list *ALL& bpf related config options in your setup
> so people can reproduce you above error messages?

Sorry, my mistake. I've reworded the changelog now to fix this:

| This function is only used when CONFIG_BPF_JIT_ALWAYS_ON is disabled,
| but CONFIG_BPF_SYSCALL is enabled. When both are turned off, the
| prototype is missing but the unused function is still compiled,
| as seen from this W=1 warning:
| 
| kernel/bpf/core.c:2075:6: error: no previous prototype for 'bpf_patch_call_args' [-Werror=missing-prototypes]
| 
| Add a matching #ifdef for the definition to leave it out.

If this makes sense now, I'll send out a v3.

      Arnd
Yonghong Song May 24, 2023, 6:12 p.m. UTC | #3 
On 5/24/23 6:23 AM, Arnd Bergmann wrote:
> On Wed, May 24, 2023, at 05:05, Yonghong Song wrote:
>> On 5/23/23 12:43 PM, Arnd Bergmann wrote:
>>> From: Arnd Bergmann <arnd@arndb.de>
>>>
>>> This function has no callers and no declaration when CONFIG_BPF_JIT_ALWAYS_ON
>>> is enabled:
>>>
>>> kernel/bpf/core.c:2075:6: error: no previous prototype for 'bpf_patch_call_args' [-Werror=missing-prototypes]
>>
>> If CONFIG_BPF_JIT_ALWAYS_ON is enabled, the definition of
>> bpf_patch_call_args should be invisible. Maybe I missed something.
>> Could you list *ALL& bpf related config options in your setup
>> so people can reproduce you above error messages?
> 
> Sorry, my mistake. I've reworded the changelog now to fix this:
> 
> | This function is only used when CONFIG_BPF_JIT_ALWAYS_ON is disabled,
> | but CONFIG_BPF_SYSCALL is enabled. When both are turned off, the
> | prototype is missing but the unused function is still compiled,
> | as seen from this W=1 warning:
> |
> | kernel/bpf/core.c:2075:6: error: no previous prototype for 'bpf_patch_call_args' [-Werror=missing-prototypes]
> |
> | Add a matching #ifdef for the definition to leave it out.
> 
> If this makes sense now, I'll send out a v3.

Yes, the above new commit message sounds good to me. Thanks.

> 
>        Arnd
diff mbox series

Patch

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 7421487422d4..0926714641eb 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2064,14 +2064,16 @@  EVAL4(PROG_NAME_LIST, 416, 448, 480, 512)
 };
 #undef PROG_NAME_LIST
 #define PROG_NAME_LIST(stack_size) PROG_NAME_ARGS(stack_size),
-static u64 (*interpreters_args[])(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5,
-				  const struct bpf_insn *insn) = {
+static __maybe_unused
+u64 (*interpreters_args[])(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5,
+			   const struct bpf_insn *insn) = {
 EVAL6(PROG_NAME_LIST, 32, 64, 96, 128, 160, 192)
 EVAL6(PROG_NAME_LIST, 224, 256, 288, 320, 352, 384)
 EVAL4(PROG_NAME_LIST, 416, 448, 480, 512)
 };
 #undef PROG_NAME_LIST
 
+#ifdef CONFIG_BPF_SYSCALL
 void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth)
 {
 	stack_depth = max_t(u32, stack_depth, 1);
@@ -2080,6 +2082,7 @@  void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth)
 		__bpf_call_base_args;
 	insn->code = BPF_JMP | BPF_CALL_ARGS;
 }
+#endif
 
 #else
 static unsigned int __bpf_prog_ret0_warn(const void *ctx,