* [PATCH v1 1/1] bpf: Mark bpf_stream_vprintk_impl() with __printf() attribute
@ 2025-12-08 15:48 Andy Shevchenko
2025-12-09 9:14 ` Alexei Starovoitov
0 siblings, 1 reply; 2+ messages in thread
From: Andy Shevchenko @ 2025-12-08 15:48 UTC (permalink / raw)
To: Alexei Starovoitov, Kumar Kartikeya Dwivedi, Puranjay Mohan, bpf,
linux-kernel
Cc: Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau,
Eduard Zingerman, Song Liu, Yonghong Song, John Fastabend,
KP Singh, Stanislav Fomichev, Hao Luo, Jiri Olsa, Alan Maguire,
Mirsad Todorovac, Andy Shevchenko
bpf_stream_vprintk_impl() is using printf() type of format, and compiler
is not happy about them as is:
kernel/bpf/stream.c:241:9: error: function ‘bpf_stream_vprintk_impl’ might be a candidate for ‘gnu_printf’ format attribute [-Werror=suggest-attribute=format]
241 | ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt__str, data.bin_args);
| ^~~
Fix the compilation errors by adding __printf() attribute.
Fixes: 5ab154f1463a ("bpf: Introduce BPF standard streams")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
kernel/bpf/stream.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/bpf/stream.c b/kernel/bpf/stream.c
index 0b6bc3f30335..4bff72e3c16f 100644
--- a/kernel/bpf/stream.c
+++ b/kernel/bpf/stream.c
@@ -212,6 +212,7 @@ __bpf_kfunc_start_defs();
* Avoid using enum bpf_stream_id so that kfunc users don't have to pull in the
* enum in headers.
*/
+__printf(2, 0)
__bpf_kfunc int bpf_stream_vprintk_impl(int stream_id, const char *fmt__str, const void *args,
u32 len__sz, void *aux__prog)
{
--
2.50.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH v1 1/1] bpf: Mark bpf_stream_vprintk_impl() with __printf() attribute
2025-12-08 15:48 [PATCH v1 1/1] bpf: Mark bpf_stream_vprintk_impl() with __printf() attribute Andy Shevchenko
@ 2025-12-09 9:14 ` Alexei Starovoitov
0 siblings, 0 replies; 2+ messages in thread
From: Alexei Starovoitov @ 2025-12-09 9:14 UTC (permalink / raw)
To: Andy Shevchenko
Cc: Alexei Starovoitov, Kumar Kartikeya Dwivedi, Puranjay Mohan, bpf,
LKML, Daniel Borkmann, Andrii Nakryiko, Martin KaFai Lau,
Eduard Zingerman, Song Liu, Yonghong Song, John Fastabend,
KP Singh, Stanislav Fomichev, Hao Luo, Jiri Olsa, Alan Maguire,
Mirsad Todorovac
On Tue, Dec 9, 2025 at 12:49 AM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> bpf_stream_vprintk_impl() is using printf() type of format, and compiler
> is not happy about them as is:
>
> kernel/bpf/stream.c:241:9: error: function ‘bpf_stream_vprintk_impl’ might be a candidate for ‘gnu_printf’ format attribute [-Werror=suggest-attribute=format]
> 241 | ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt__str, data.bin_args);
> | ^~~
>
> Fix the compilation errors by adding __printf() attribute.
>
> Fixes: 5ab154f1463a ("bpf: Introduce BPF standard streams")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> kernel/bpf/stream.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/bpf/stream.c b/kernel/bpf/stream.c
> index 0b6bc3f30335..4bff72e3c16f 100644
> --- a/kernel/bpf/stream.c
> +++ b/kernel/bpf/stream.c
> @@ -212,6 +212,7 @@ __bpf_kfunc_start_defs();
> * Avoid using enum bpf_stream_id so that kfunc users don't have to pull in the
> * enum in headers.
> */
> +__printf(2, 0)
> __bpf_kfunc int bpf_stream_vprintk_impl(int stream_id, const char *fmt__str, const void *args,
same issue.
The addition of this attribute doesn't make any difference, since kfunc
protos are autogenerated from BTF and it's not there.
pw-bot: cr
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