From: Dominique Martinet <asmadeus@codewreck.org>
Date: Sun, 24 Apr 2022 14:10:21 +0900
Subject: bpftool, musl compat: Replace nftw with FTW_ACTIONRETVAL
Patch-mainline: v5.19-rc1
Git-commit: 93bc2e9e943d20a51473a49009db3243de6e098d
References: jsc#PED-1377
musl nftw implementation does not support FTW_ACTIONRETVAL. There have been
multiple attempts at pushing the feature in musl upstream, but it has been
refused or ignored all the times:
https://www.openwall.com/lists/musl/2021/03/26/1
https://www.openwall.com/lists/musl/2022/01/22/1
In this case we only care about /proc/<pid>/fd/<fd>, so it's not too difficult
to reimplement directly instead, and the new implementation makes 'bpftool perf'
slightly faster because it doesn't needlessly stat/readdir unneeded directories
(54ms -> 13ms on my machine).
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20220424051022.2619648-4-asmadeus@codewreck.org
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
tools/bpf/bpftool/perf.c | 116 +++++++++++++++++++++++------------------------
1 file changed, 59 insertions(+), 57 deletions(-)
--- a/tools/bpf/bpftool/perf.c
+++ b/tools/bpf/bpftool/perf.c
@@ -11,7 +11,7 @@
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
-#include <ftw.h>
+#include <dirent.h>
#include <bpf/bpf.h>
@@ -147,81 +147,83 @@ static void print_perf_plain(int pid, in
}
}
-static int show_proc(const char *fpath, const struct stat *sb,
- int tflag, struct FTW *ftwbuf)
+static int show_proc(void)
{
+ struct dirent *proc_de, *pid_fd_de;
__u64 probe_offset, probe_addr;
__u32 len, prog_id, fd_type;
- int err, pid = 0, fd = 0;
+ DIR *proc, *pid_fd;
+ int err, pid, fd;
const char *pch;
char buf[4096];
- /* prefix always /proc */
- pch = fpath + 5;
- if (*pch == '\0')
- return 0;
-
- /* pid should be all numbers */
- pch++;
- while (isdigit(*pch)) {
- pid = pid * 10 + *pch - '0';
- pch++;
- }
- if (*pch == '\0')
- return 0;
- if (*pch != '/')
- return FTW_SKIP_SUBTREE;
-
- /* check /proc/<pid>/fd directory */
- pch++;
- if (strncmp(pch, "fd", 2))
- return FTW_SKIP_SUBTREE;
- pch += 2;
- if (*pch == '\0')
- return 0;
- if (*pch != '/')
- return FTW_SKIP_SUBTREE;
-
- /* check /proc/<pid>/fd/<fd_num> */
- pch++;
- while (isdigit(*pch)) {
- fd = fd * 10 + *pch - '0';
- pch++;
- }
- if (*pch != '\0')
- return FTW_SKIP_SUBTREE;
-
- /* query (pid, fd) for potential perf events */
- len = sizeof(buf);
- err = bpf_task_fd_query(pid, fd, 0, buf, &len, &prog_id, &fd_type,
- &probe_offset, &probe_addr);
- if (err < 0)
- return 0;
+ proc = opendir("/proc");
+ if (!proc)
+ return -1;
- if (json_output)
- print_perf_json(pid, fd, prog_id, fd_type, buf, probe_offset,
- probe_addr);
- else
- print_perf_plain(pid, fd, prog_id, fd_type, buf, probe_offset,
- probe_addr);
+ while ((proc_de = readdir(proc))) {
+ pid = 0;
+ pch = proc_de->d_name;
+
+ /* pid should be all numbers */
+ while (isdigit(*pch)) {
+ pid = pid * 10 + *pch - '0';
+ pch++;
+ }
+ if (*pch != '\0')
+ continue;
+ err = snprintf(buf, sizeof(buf), "/proc/%s/fd", proc_de->d_name);
+ if (err < 0 || err >= (int)sizeof(buf))
+ continue;
+
+ pid_fd = opendir(buf);
+ if (!pid_fd)
+ continue;
+
+ while ((pid_fd_de = readdir(pid_fd))) {
+ fd = 0;
+ pch = pid_fd_de->d_name;
+
+ /* fd should be all numbers */
+ while (isdigit(*pch)) {
+ fd = fd * 10 + *pch - '0';
+ pch++;
+ }
+ if (*pch != '\0')
+ continue;
+
+ /* query (pid, fd) for potential perf events */
+ len = sizeof(buf);
+ err = bpf_task_fd_query(pid, fd, 0, buf, &len,
+ &prog_id, &fd_type,
+ &probe_offset, &probe_addr);
+ if (err < 0)
+ continue;
+
+ if (json_output)
+ print_perf_json(pid, fd, prog_id, fd_type, buf,
+ probe_offset, probe_addr);
+ else
+ print_perf_plain(pid, fd, prog_id, fd_type, buf,
+ probe_offset, probe_addr);
+ }
+ closedir(pid_fd);
+ }
+ closedir(proc);
return 0;
}
static int do_show(int argc, char **argv)
{
- int flags = FTW_ACTIONRETVAL | FTW_PHYS;
- int err = 0, nopenfd = 16;
+ int err;
if (!has_perf_query_support())
return -1;
if (json_output)
jsonw_start_array(json_wtr);
- if (nftw("/proc", show_proc, nopenfd, flags) == -1) {
- p_err("%s", strerror(errno));
- err = -1;
- }
+ err = show_proc();
if (json_output)
jsonw_end_array(json_wtr);