On Fri, May 24, 2024 at 6:21 AM Mykyta Yatsenko
<mykyta.yatsenko5@xxxxxxxxx> wrote:
>
> From: Mykyta Yatsenko <yatsenko@xxxxxxxx>
>
> Configure logging verbosity by setting LIBBPF_LOG_LEVEL environment
> variable, which is applied only to default logger. Once user set their
> custom logging callback, it is up to them to handle filtering.
>
> Signed-off-by: Mykyta Yatsenko <yatsenko@xxxxxxxx>
> ---
> Documentation/bpf/libbpf/libbpf_overview.rst | 7 ++++++
> tools/lib/bpf/libbpf.c | 24 +++++++++++++++++++-
> tools/lib/bpf/libbpf.h | 5 +++-
> 3 files changed, 34 insertions(+), 2 deletions(-)
>
I did a few tweaks, mentioned below, and applied to bpf-next. Thanks!
> diff --git a/Documentation/bpf/libbpf/libbpf_overview.rst b/Documentation/bpf/libbpf/libbpf_overview.rst
> index f36a2d4ffea2..982dfd71a13d 100644
> --- a/Documentation/bpf/libbpf/libbpf_overview.rst
> +++ b/Documentation/bpf/libbpf/libbpf_overview.rst
> @@ -219,6 +219,13 @@ compilation and skeleton generation. Using Libbpf-rs will make building user
> space part of the BPF application easier. Note that the BPF program themselves
> must still be written in plain C.
>
> +libbpf logging
> +==============
> +
> +By default, libbpf logs informational and warning messages to stderr. The verbosity of these
> +messages can be controlled by setting the environment variable LIBBPF_LOG_LEVEL to either warn,
> +info, or debug. A custom log callback can be set using ``libbpf_set_print()``.
> +
reformatted this to use line length consistent with the rest of the document
> Additional Documentation
> ========================
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 5401f2df463d..d0465ca74afc 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -229,7 +229,29 @@ static const char * const prog_type_name[] = {
> static int __base_pr(enum libbpf_print_level level, const char *format,
> va_list args)
> {
> - if (level == LIBBPF_DEBUG)
> + static enum libbpf_print_level min_level = LIBBPF_INFO;
> + static const char *env_var = "LIBBPF_LOG_LEVEL";
no need for this to be static
> + static bool initialized;
> +
> + if (!initialized) {
> + char *verbosity;
> +
> + initialized = true;
> + verbosity = getenv(env_var);
> + if (verbosity) {
> + if (strcasecmp(verbosity, "warn") == 0)
> + min_level = LIBBPF_WARN;
> + else if (strcasecmp(verbosity, "debug") == 0)
> + min_level = LIBBPF_DEBUG;
> + else if (strcasecmp(verbosity, "info") == 0)
> + min_level = LIBBPF_INFO;
> + else
> + fprintf(stderr, "Unexpected value of %s env variable\n", env_var);
I've added "libbpf: " prefix and expanded the message with supported values.
> + }
> + }
> +
> + /* if too verbose, skip logging */
> + if (level > min_level)
> return 0;
>
> return vfprintf(stderr, format, args);
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index c3f77d9260fe..26e4e35528c5 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -98,7 +98,10 @@ typedef int (*libbpf_print_fn_t)(enum libbpf_print_level level,
>
> /**
> * @brief **libbpf_set_print()** sets user-provided log callback function to
> - * be used for libbpf warnings and informational messages.
> + * be used for libbpf warnings and informational messages. If the user callback
> + * is not set, messages are logged to stderr by default. The verbosity of these
> + * messages can be controlled by setting the environment variable
> + * LIBBPF_LOG_LEVEL to either warn, info, or debug.
> * @param fn The log print function. If NULL, libbpf won't print anything.
> * @return Pointer to old print function.
> *
> --
> 2.45.0
>
