Re: [PATCH 2/2] selftests/bpf: Skip bpffs debug iter checks when unavailable in test_bpffs

[Yonghong Song]

On 3/10/26 3:21 AM, Sun Jian wrote:

maps.debug/progs.debug may be inaccessible or absent (EPERM/EACCES/ENOENT)
in some environments, which used to abort test_bpffs before it exercised

In which situation these two files have issues? This already root
access. If file operation failed, that must be due to your special
situation.

the pin and rename checks. Treat these errors as "iter unavailable", log
an INFO message, and continue with the core bpffs tests.

Signed-off-by: Sun Jian <sun.jian.k...@gmail.com>
---
  .../selftests/bpf/prog_tests/test_bpffs.c     | 43 ++++++++++++++++---
  1 file changed, 36 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/test_bpffs.c 
b/tools/testing/selftests/bpf/prog_tests/test_bpffs.c
index e8021ff0581c..95a7d2582ba7 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_bpffs.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_bpffs.c
@@ -11,15 +11,18 @@
  /* TDIR must be in a location we can create a directory in. */
  #define TDIR "/tmp/test_bpffs_testdir"

-static int read_iter(char *file)

+static int read_iter(const char *file, int *save_errno)
  {
        /* 1024 should be enough to get contiguous 4 "iter" letters at some 
point */
        char buf[1024];
        int fd, len;

fd = open(file, O_RDONLY);

-       if (fd < 0)
+       if (fd < 0) {
+               if (save_errno)
+                       *save_errno = errno;
                return -1;
+       }
        while ((len = read(fd, buf, sizeof(buf) - 1)) > 0) {
                buf[len] = '\0';
                if (strstr(buf, "iter")) {
@@ -27,10 +30,33 @@ static int read_iter(char *file)
                        return 0;
                }
        }
+       if (save_errno)
+               *save_errno = (len < 0) ? errno : 0;
        close(fd);
        return -1;
  }

+static bool is_iter_skip_err(int err, int serrno)

+{
+       return err && (serrno == EPERM || serrno == EACCES || serrno == ENOENT);
+}
+
+static int read_iter_or_skip(const char *file)
+{
+       int serrno = 0;
+       int err = read_iter(file, &serrno);
+
+       if (is_iter_skip_err(err, serrno)) {
+               fprintf(stderr,
+                       "INFO: %s unavailable (%d), skipping iter check\n",
+                       file,
+                       serrno);
+               return 0;
+       }
+
+       return err;
+}
+
  static int fn(void)
  {
        struct stat a, b, c;
@@ -69,13 +95,16 @@ static int fn(void)
        if (!ASSERT_OK(err, "mount bpffs " TDIR "/fs2"))
                goto out;

- err = read_iter(TDIR "/fs1/maps.debug");

-       if (!ASSERT_OK(err, "reading " TDIR "/fs1/maps.debug"))
+       err = read_iter_or_skip(TDIR "/fs1/maps.debug");
+       if (err) {
+               ASSERT_OK(err, "reading " TDIR "/fs1/maps.debug");
                goto out;
-       err = read_iter(TDIR "/fs2/progs.debug");
-       if (!ASSERT_OK(err, "reading " TDIR "/fs2/progs.debug"))
+       }
+       err = read_iter_or_skip(TDIR "/fs2/progs.debug");
+       if (err) {
+               ASSERT_OK(err, "reading " TDIR "/fs2/progs.debug");
                goto out;
-
+       }
        err = mkdir(TDIR "/fs1/a", 0777);
        if (!ASSERT_OK(err, "creating " TDIR "/fs1/a"))
                goto out;