Commit a8a1f7d0 authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Alexei Starovoitov
Browse files

libbpf: fix libbpf_print 



With the recent print rework we now have the following problem:
pr_{warning,info,debug} expand to __pr which calls libbpf_print.
libbpf_print does va_start and calls __libbpf_pr with va_list argument.
In __base_pr we again do va_start. Because the next argument is a
va_list, we don't get correct pointer to the argument (and print noting
in my case, I don't know why it doesn't crash tbh).

Fix this by changing libbpf_print_fn_t signature to accept va_list and
remove unneeded calls to va_start in the existing users.

Alternatively, this can we solved by exporting __libbpf_pr and
changing __pr macro to (and killing libbpf_print):
{
	if (__libbpf_pr)
		__libbpf_pr(level, "libbpf: " fmt, ##__VA_ARGS__)
}

Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 1728b111

tools/lib/bpf/libbpf.c

+4 −10
Original line number Diff line number Diff line
@@ -54,22 +54,16 @@ 


#define __printf(a, b)	__attribute__((format(printf, a, b)))



__printf(2, 3)

static int __base_pr(enum libbpf_print_level level, const char *format, ...)

static int __base_pr(enum libbpf_print_level level, const char *format,

		     va_list args)

{

	va_list args;

	int err;



	if (level == LIBBPF_DEBUG)

		return 0;



	va_start(args, format);

	err = vfprintf(stderr, format, args);

	va_end(args);

	return err;

	return vfprintf(stderr, format, args);

}



static __printf(2, 3) libbpf_print_fn_t __libbpf_pr = __base_pr;

static libbpf_print_fn_t __libbpf_pr = __base_pr;



void libbpf_set_print(libbpf_print_fn_t fn)

{

tools/lib/bpf/libbpf.h

+1 −2
Original line number Diff line number Diff line
@@ -54,8 +54,7 @@ enum libbpf_print_level { 
};



typedef int (*libbpf_print_fn_t)(enum libbpf_print_level level,

				 const char *, ...)

	__attribute__((format(printf, 2, 3)));

				 const char *, va_list ap);



LIBBPF_API void libbpf_set_print(libbpf_print_fn_t fn);

tools/perf/util/bpf-loader.c

+2 −8
Original line number Diff line number Diff line
@@ -25,15 +25,9 @@ 
#include "c++/clang-c.h"



static int libbpf_perf_print(enum libbpf_print_level level __attribute__((unused)),

			      const char *fmt, ...)

			      const char *fmt, va_list args)

{

	va_list args;

	int ret;



	va_start(args, fmt);

	ret = veprintf(1, verbose, pr_fmt(fmt), args);

	va_end(args);

	return ret;

	return veprintf(1, verbose, pr_fmt(fmt), args);

}



struct bpf_prog_priv {

tools/testing/selftests/bpf/test_btf.c

+2 −11
Original line number Diff line number Diff line
@@ -52,19 +52,10 @@ static int count_result(int err) 
	return err;

}



#define __printf(a, b)	__attribute__((format(printf, a, b)))



__printf(2, 3)

static int __base_pr(enum libbpf_print_level level __attribute__((unused)),

		     const char *format, ...)

		     const char *format, va_list args)

{

	va_list args;

	int err;



	va_start(args, format);

	err = vfprintf(stderr, format, args);

	va_end(args);

	return err;

	return vfprintf(stderr, format, args);

}



#define BTF_INFO_ENC(kind, kind_flag, vlen)			\

tools/testing/selftests/bpf/test_libbpf_open.c

+2 −8
Original line number Diff line number Diff line
@@ -36,19 +36,13 @@ static void usage(char *argv[]) 


static bool debug = 0;

static int libbpf_debug_print(enum libbpf_print_level level,

			      const char *fmt, ...)

			      const char *fmt, va_list args)

{

	va_list args;

	int ret;



	if (level == LIBBPF_DEBUG && !debug)

		return 0;



	va_start(args, fmt);

	fprintf(stderr, "[%d] ", level);

	ret = vfprintf(stderr, fmt, args);

	va_end(args);

	return ret;

	return vfprintf(stderr, fmt, args);

}



#define EXIT_FAIL_LIBBPF EXIT_FAILURE

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