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: Stanislav Fomichev <sdf@google.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Stanislav Fomichev 2019-02-04 16:20:55 -08:00 committed by Alexei Starovoitov
parent 1728b11110
commit a8a1f7d09c
6 changed files with 13 additions and 47 deletions

View File

@ -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)
{

View File

@ -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);

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@ -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 {

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@ -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) \

View File

@ -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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@ -1785,18 +1785,12 @@ static void test_task_fd_query_tp(void)
}
static int libbpf_debug_print(enum libbpf_print_level level,
const char *format, ...)
const char *format, va_list args)
{
va_list args;
int ret;
if (level == LIBBPF_DEBUG)
return 0;
va_start(args, format);
ret = vfprintf(stderr, format, args);
va_end(args);
return ret;
return vfprintf(stderr, format, args);
}
static void test_reference_tracking()