Commit eb4e7726 authored by Mykyta Yatsenko's avatar Mykyta Yatsenko Committed by Andrii Nakryiko
Browse files

libbpf: Configure log verbosity with env variable 



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: default avatarMykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240524131840.114289-1-yatsenko@meta.com
parent 4b3529ed

Documentation/bpf/libbpf/libbpf_overview.rst

+8 −0
Original line number Diff line number Diff line
@@ -219,6 +219,14 @@ 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()``.



Additional Documentation

========================

tools/lib/bpf/libbpf.c

+24 −1
Original line number Diff line number Diff line
@@ -229,7 +229,30 @@ 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)

	const char *env_var = "LIBBPF_LOG_LEVEL";

	static enum libbpf_print_level min_level = LIBBPF_INFO;

	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, "libbpf: unrecognized '%s' envvar value: '%s', should be one of 'warn', 'debug', or 'info'.\n",

					env_var, verbosity);

		}

	}



	/* if too verbose, skip logging  */

	if (level > min_level)

		return 0;



	return vfprintf(stderr, format, args);

tools/lib/bpf/libbpf.h

+4 −1
Original line number Diff line number Diff line
@@ -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.

 *