[PATCH v3] perf build: Build error in libbpf with EXTRA_CFLAGS="-Wp,-D_FORTIFY_SOURCE=2 -O2"
From: Thomas Richter
Date: Mon Jul 30 2018 - 04:54:03 EST
commit 531b014e7a2f ("tools: bpf: make use of reallocarray")
causes a compiler error when building the perf tool in the linux-next
tree. Compile file tools/lib/bpf/libbpf.c on a FEDORA 28
installation with gcc compiler
version: gcc (GCC) 8.0.1 20180324 (Red Hat 8.0.1-0.20)
shows this error message:
[root@p23lp27] # make V=1 EXTRA_CFLAGS="-Wp,-D_FORTIFY_SOURCE=2 -O2"
[...]
make -f /home6/tmricht/linux-next/tools/build/Makefile.build
dir=./util/scripting-engines obj=libperf
libbpf.c: In function âbpf_object__elf_collectâ:
libbpf.c:811:15: error: ignoring return value of âstrerror_râ,
declared with attribute warn_unused_result [-Werror=unused-result]
strerror_r(-err, errmsg, sizeof(errmsg));
^
cc1: all warnings being treated as errors
mv: cannot stat './.libbpf.o.tmp': No such file or directory
/home6/tmricht/linux-next/tools/build/Makefile.build:96: recipe for target 'libbpf.o' failed
Replace all occurrences of strerror() by calls to strerror_r().
To keep the compiler quiet also use the return value from strerror_r()
otherwise a 'variable set but not use' warning which is treated as error
terminates the compile.
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>
Suggested-by: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>
Suggested-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Reviewed-by: Hendrik Brueckner <brueckner@xxxxxxxxxxxxx>
Signed-off-by: Thomas Richter <tmricht@xxxxxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 42 +++++++++++++++++++++++++++++-------------
1 file changed, 29 insertions(+), 13 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 73465caa33ba..e040c6b5fde9 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -468,8 +468,10 @@ static int bpf_object__elf_init(struct bpf_object *obj)
} else {
obj->efile.fd = open(obj->path, O_RDONLY);
if (obj->efile.fd < 0) {
- pr_warning("failed to open %s: %s\n", obj->path,
- strerror(errno));
+ char errmsg[STRERR_BUFSIZE];
+ char *cp = strerror_r(errno, errmsg, sizeof(errmsg));
+
+ pr_warning("failed to open %s: %s\n", obj->path, cp);
return -errno;
}
@@ -808,10 +810,11 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
data->d_size, name, idx);
if (err) {
char errmsg[STRERR_BUFSIZE];
+ char *cp = strerror_r(-err, errmsg,
+ sizeof(errmsg));
- strerror_r(-err, errmsg, sizeof(errmsg));
pr_warning("failed to alloc program %s (%s): %s",
- name, obj->path, errmsg);
+ name, obj->path, cp);
}
} else if (sh.sh_type == SHT_REL) {
void *reloc = obj->efile.reloc;
@@ -1097,6 +1100,7 @@ bpf_object__create_maps(struct bpf_object *obj)
for (i = 0; i < obj->nr_maps; i++) {
struct bpf_map *map = &obj->maps[i];
struct bpf_map_def *def = &map->def;
+ char *cp, errmsg[STRERR_BUFSIZE];
int *pfd = &map->fd;
if (map->fd >= 0) {
@@ -1124,8 +1128,9 @@ bpf_object__create_maps(struct bpf_object *obj)
*pfd = bpf_create_map_xattr(&create_attr);
if (*pfd < 0 && create_attr.btf_key_type_id) {
+ cp = strerror_r(errno, errmsg, sizeof(errmsg));
pr_warning("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
- map->name, strerror(errno), errno);
+ map->name, cp, errno);
create_attr.btf_fd = 0;
create_attr.btf_key_type_id = 0;
create_attr.btf_value_type_id = 0;
@@ -1138,9 +1143,9 @@ bpf_object__create_maps(struct bpf_object *obj)
size_t j;
err = *pfd;
+ cp = strerror_r(errno, errmsg, sizeof(errmsg));
pr_warning("failed to create map (name: '%s'): %s\n",
- map->name,
- strerror(errno));
+ map->name, cp);
for (j = 0; j < i; j++)
zclose(obj->maps[j].fd);
return err;
@@ -1292,6 +1297,7 @@ load_program(enum bpf_prog_type type, enum bpf_attach_type expected_attach_type,
char *license, u32 kern_version, int *pfd, int prog_ifindex)
{
struct bpf_load_program_attr load_attr;
+ char *cp, errmsg[STRERR_BUFSIZE];
char *log_buf;
int ret;
@@ -1321,7 +1327,8 @@ load_program(enum bpf_prog_type type, enum bpf_attach_type expected_attach_type,
}
ret = -LIBBPF_ERRNO__LOAD;
- pr_warning("load bpf program failed: %s\n", strerror(errno));
+ cp = strerror_r(errno, errmsg, sizeof(errmsg));
+ pr_warning("load bpf program failed: %s\n", cp);
if (log_buf && log_buf[0] != '\0') {
ret = -LIBBPF_ERRNO__VERIFY;
@@ -1620,6 +1627,7 @@ int bpf_object__load(struct bpf_object *obj)
static int check_path(const char *path)
{
+ char *cp, errmsg[STRERR_BUFSIZE];
struct statfs st_fs;
char *dname, *dir;
int err = 0;
@@ -1633,7 +1641,8 @@ static int check_path(const char *path)
dir = dirname(dname);
if (statfs(dir, &st_fs)) {
- pr_warning("failed to statfs %s: %s\n", dir, strerror(errno));
+ cp = strerror_r(errno, errmsg, sizeof(errmsg));
+ pr_warning("failed to statfs %s: %s\n", dir, cp);
err = -errno;
}
free(dname);
@@ -1649,6 +1658,7 @@ static int check_path(const char *path)
int bpf_program__pin_instance(struct bpf_program *prog, const char *path,
int instance)
{
+ char *cp, errmsg[STRERR_BUFSIZE];
int err;
err = check_path(path);
@@ -1667,7 +1677,8 @@ int bpf_program__pin_instance(struct bpf_program *prog, const char *path,
}
if (bpf_obj_pin(prog->instances.fds[instance], path)) {
- pr_warning("failed to pin program: %s\n", strerror(errno));
+ cp = strerror_r(errno, errmsg, sizeof(errmsg));
+ pr_warning("failed to pin program: %s\n", cp);
return -errno;
}
pr_debug("pinned program '%s'\n", path);
@@ -1677,13 +1688,16 @@ int bpf_program__pin_instance(struct bpf_program *prog, const char *path,
static int make_dir(const char *path)
{
+ char *cp, errmsg[STRERR_BUFSIZE];
int err = 0;
if (mkdir(path, 0700) && errno != EEXIST)
err = -errno;
- if (err)
- pr_warning("failed to mkdir %s: %s\n", path, strerror(-err));
+ if (err) {
+ cp = strerror_r(-err, errmsg, sizeof(errmsg));
+ pr_warning("failed to mkdir %s: %s\n", path, cp);
+ }
return err;
}
@@ -1730,6 +1744,7 @@ int bpf_program__pin(struct bpf_program *prog, const char *path)
int bpf_map__pin(struct bpf_map *map, const char *path)
{
+ char *cp, errmsg[STRERR_BUFSIZE];
int err;
err = check_path(path);
@@ -1742,7 +1757,8 @@ int bpf_map__pin(struct bpf_map *map, const char *path)
}
if (bpf_obj_pin(map->fd, path)) {
- pr_warning("failed to pin map: %s\n", strerror(errno));
+ cp = strerror_r(errno, errmsg, sizeof(errmsg));
+ pr_warning("failed to pin map: %s\n", cp);
return -errno;
}
--
2.16.4