From: Hechao Li hechaol@fb.com
[ Upstream commit 1162f844030ac1ac7321b5e8f6c9badc7a11428f ]
Currently, when bpftool cgroup show <path> has an error, no error message is printed. This is confusing because the user may think the result is empty.
Before the change:
$ bpftool cgroup show /sys/fs/cgroup ID AttachType AttachFlags Name $ echo $? 255
After the change: $ ./bpftool cgroup show /sys/fs/cgroup Error: can't query bpf programs attached to /sys/fs/cgroup: Operation not permitted
v2: Rename check_query_cgroup_progs to cgroup_has_attached_progs
Signed-off-by: Hechao Li hechaol@fb.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Link: https://lore.kernel.org/bpf/20191224011742.3714301-1-hechaol@fb.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/bpf/bpftool/cgroup.c | 56 ++++++++++++++++++++++++++------------ 1 file changed, 39 insertions(+), 17 deletions(-)
diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c index 1ef45e55039e1..2f017caa678dc 100644 --- a/tools/bpf/bpftool/cgroup.c +++ b/tools/bpf/bpftool/cgroup.c @@ -117,6 +117,25 @@ static int count_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type) return prog_cnt; }
+static int cgroup_has_attached_progs(int cgroup_fd) +{ + enum bpf_attach_type type; + bool no_prog = true; + + for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) { + int count = count_attached_bpf_progs(cgroup_fd, type); + + if (count < 0 && errno != EINVAL) + return -1; + + if (count > 0) { + no_prog = false; + break; + } + } + + return no_prog ? 0 : 1; +} static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type, int level) { @@ -161,6 +180,7 @@ static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type, static int do_show(int argc, char **argv) { enum bpf_attach_type type; + int has_attached_progs; const char *path; int cgroup_fd; int ret = -1; @@ -192,6 +212,16 @@ static int do_show(int argc, char **argv) goto exit; }
+ has_attached_progs = cgroup_has_attached_progs(cgroup_fd); + if (has_attached_progs < 0) { + p_err("can't query bpf programs attached to %s: %s", + path, strerror(errno)); + goto exit_cgroup; + } else if (!has_attached_progs) { + ret = 0; + goto exit_cgroup; + } + if (json_output) jsonw_start_array(json_wtr); else @@ -212,6 +242,7 @@ static int do_show(int argc, char **argv) if (json_output) jsonw_end_array(json_wtr);
+exit_cgroup: close(cgroup_fd); exit: return ret; @@ -228,7 +259,7 @@ static int do_show_tree_fn(const char *fpath, const struct stat *sb, int typeflag, struct FTW *ftw) { enum bpf_attach_type type; - bool skip = true; + int has_attached_progs; int cgroup_fd;
if (typeflag != FTW_D) @@ -240,22 +271,13 @@ static int do_show_tree_fn(const char *fpath, const struct stat *sb, return SHOW_TREE_FN_ERR; }
- for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) { - int count = count_attached_bpf_progs(cgroup_fd, type); - - if (count < 0 && errno != EINVAL) { - p_err("can't query bpf programs attached to %s: %s", - fpath, strerror(errno)); - close(cgroup_fd); - return SHOW_TREE_FN_ERR; - } - if (count > 0) { - skip = false; - break; - } - } - - if (skip) { + has_attached_progs = cgroup_has_attached_progs(cgroup_fd); + if (has_attached_progs < 0) { + p_err("can't query bpf programs attached to %s: %s", + fpath, strerror(errno)); + close(cgroup_fd); + return SHOW_TREE_FN_ERR; + } else if (!has_attached_progs) { close(cgroup_fd); return 0; }