* [PATCH bpf-next] libbpf: preserve errno across pr_warn/pr_info/pr_debug
@ 2022-08-10 18:34 Andrii Nakryiko
2022-08-10 18:43 ` Daniel Müller
2022-08-10 18:50 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 3+ messages in thread
From: Andrii Nakryiko @ 2022-08-10 18:34 UTC (permalink / raw)
To: bpf, ast, daniel; +Cc: andrii, kernel-team
As suggested in [0], make sure that libbpf_print saves and restored
errno and as such guaranteed that no matter what actual print callback
user installs, macros like pr_warn/pr_info/pr_debug are completely
transparent as far as errno goes.
While libbpf code is pretty careful about not clobbering important errno
values accidentally with pr_warn(), it's a trivial change to make sure
that pr_warn can be used anywhere without a risk of clobbering errno.
No functional changes, just future proofing.
[0] https://github.com/libbpf/libbpf/pull/536
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
tools/lib/bpf/libbpf.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index f7364ea82ac1..917d975bd4c6 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -223,13 +223,18 @@ __printf(2, 3)
void libbpf_print(enum libbpf_print_level level, const char *format, ...)
{
va_list args;
+ int old_errno;
if (!__libbpf_pr)
return;
+ old_errno = errno;
+
va_start(args, format);
__libbpf_pr(level, format, args);
va_end(args);
+
+ errno = old_errno;
}
static void pr_perm_msg(int err)
--
2.30.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH bpf-next] libbpf: preserve errno across pr_warn/pr_info/pr_debug
2022-08-10 18:34 [PATCH bpf-next] libbpf: preserve errno across pr_warn/pr_info/pr_debug Andrii Nakryiko
@ 2022-08-10 18:43 ` Daniel Müller
2022-08-10 18:50 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Daniel Müller @ 2022-08-10 18:43 UTC (permalink / raw)
To: Andrii Nakryiko; +Cc: bpf, ast, daniel, kernel-team
On Wed, Aug 10, 2022 at 11:34:25AM -0700, Andrii Nakryiko wrote:
> As suggested in [0], make sure that libbpf_print saves and restored
> errno and as such guaranteed that no matter what actual print callback
> user installs, macros like pr_warn/pr_info/pr_debug are completely
> transparent as far as errno goes.
>
> While libbpf code is pretty careful about not clobbering important errno
> values accidentally with pr_warn(), it's a trivial change to make sure
> that pr_warn can be used anywhere without a risk of clobbering errno.
>
> No functional changes, just future proofing.
>
> [0] https://github.com/libbpf/libbpf/pull/536
>
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
> ---
> tools/lib/bpf/libbpf.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index f7364ea82ac1..917d975bd4c6 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -223,13 +223,18 @@ __printf(2, 3)
> void libbpf_print(enum libbpf_print_level level, const char *format, ...)
> {
> va_list args;
> + int old_errno;
>
> if (!__libbpf_pr)
> return;
>
> + old_errno = errno;
> +
> va_start(args, format);
> __libbpf_pr(level, format, args);
> va_end(args);
> +
> + errno = old_errno;
> }
>
> static void pr_perm_msg(int err)
> --
> 2.30.2
>
The change looks good to me.
Acked-by: Daniel Müller <deso@posteo.net>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH bpf-next] libbpf: preserve errno across pr_warn/pr_info/pr_debug
2022-08-10 18:34 [PATCH bpf-next] libbpf: preserve errno across pr_warn/pr_info/pr_debug Andrii Nakryiko
2022-08-10 18:43 ` Daniel Müller
@ 2022-08-10 18:50 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2022-08-10 18:50 UTC (permalink / raw)
To: Andrii Nakryiko; +Cc: bpf, ast, daniel, kernel-team
Hello:
This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:
On Wed, 10 Aug 2022 11:34:25 -0700 you wrote:
> As suggested in [0], make sure that libbpf_print saves and restored
> errno and as such guaranteed that no matter what actual print callback
> user installs, macros like pr_warn/pr_info/pr_debug are completely
> transparent as far as errno goes.
>
> While libbpf code is pretty careful about not clobbering important errno
> values accidentally with pr_warn(), it's a trivial change to make sure
> that pr_warn can be used anywhere without a risk of clobbering errno.
>
> [...]
Here is the summary with links:
- [bpf-next] libbpf: preserve errno across pr_warn/pr_info/pr_debug
https://git.kernel.org/bpf/bpf-next/c/d7c5802faff6
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
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2022-08-10 18:34 [PATCH bpf-next] libbpf: preserve errno across pr_warn/pr_info/pr_debug Andrii Nakryiko
2022-08-10 18:43 ` Daniel Müller
2022-08-10 18:50 ` patchwork-bot+netdevbpf
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