From: Kui-Feng Lee <sinquersw@gmail.com>
To: Manu Bretelle <chantr4@gmail.com>,
bpf@vger.kernel.org, andrii@kernel.org, daniel@iogearbox.net,
ast@kernel.org, martin.lau@linux.dev, song@kernel.org,
yonghong.song@linux.dev, john.fastabend@gmail.com,
kpsingh@kernel.org, sdf@google.com, haoluo@google.com,
jolsa@kernel.org, mykolal@fb.com, shuah@kernel.org
Subject: Re: [PATCH bpf-next] selftests/bpf: umount children of TDIR in test_bpffs
Date: Tue, 24 Oct 2023 14:29:19 -0700 [thread overview]
Message-ID: <041a3ea2-8cc6-4f0f-8ed9-6ca459e5bbb7@gmail.com> (raw)
In-Reply-To: <20231024201852.1512720-1-chantr4@gmail.com>
On 10/24/23 13:18, Manu Bretelle wrote:
> Currently this tests tries to umount /sys/kernel/debug (TDIR) but the
> system it is running on may have mounts below.
>
> For example, danobi/vmtest [0] VMs have
> mount -t tracefs tracefs /sys/kernel/debug/tracing
> as part of their init.
>
> This change list mounts and will umount any mounts below TDIR before
> umounting TDIR itself.
>
> Note that it is not umounting recursively, so in the case of a sub-mount
> of TDIR having another sub-mount, this will fail as mtab is ordered.
Should we move TID to a random path likes "/sys/kernel/debug-<pid>/"?
>
> Test:
>
> Originally:
>
> $ vmtest -k $KERNEL_REPO/arch/x86_64/boot/bzImage "./test_progs -vv -a test_bpffs"
> => bzImage
> ===> Booting
> ===> Setting up VM
> ===> Running command
> [ 2.138818] bpf_testmod: loading out-of-tree module taints kernel.
> [ 2.140913] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
> bpf_testmod.ko is already unloaded.
> Loading bpf_testmod.ko...
> Successfully loaded bpf_testmod.ko.
> test_test_bpffs:PASS:clone 0 nsec
> fn:PASS:unshare 0 nsec
> fn:PASS:mount / 0 nsec
> fn:FAIL:umount /sys/kernel/debug unexpected error: -1 (errno 16)
> bpf_testmod.ko is already unloaded.
> Loading bpf_testmod.ko...
> Successfully loaded bpf_testmod.ko.
> test_test_bpffs:PASS:clone 0 nsec
> test_test_bpffs:PASS:waitpid 0 nsec
> test_test_bpffs:FAIL:bpffs test failed 255#282 test_bpffs:FAIL
> Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED
> Successfully unloaded bpf_testmod.ko.
> Command failed with exit code: 1
>
> After this change:
>
> $ vmtest -k $KERNEL_REPO/arch/x86_64/boot/bzImage "./test_progs -vv -a test_bpffs"
> => bzImage
> ===> Booting
> ===> Setting up VM
> ===> Running command
> [ 2.035210] bpf_testmod: loading out-of-tree module taints kernel.
> [ 2.036510] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
> bpf_testmod.ko is already unloaded.
> Loading bpf_testmod.ko...
> Successfully loaded bpf_testmod.ko.
> test_test_bpffs:PASS:clone 0 nsec
> fn:PASS:unshare 0 nsec
> fn:PASS:mount / 0 nsec
> fn:PASS:accessing /etc/mtab 0 nsec
> fn:PASS:umount /sys/kernel/debug/tracing 0 nsec
> fn:PASS:umount /sys/kernel/debug 0 nsec
> fn:PASS:mount tmpfs 0 nsec
> fn:PASS:mkdir /sys/kernel/debug/fs1 0 nsec
> fn:PASS:mkdir /sys/kernel/debug/fs2 0 nsec
> fn:PASS:mount bpffs /sys/kernel/debug/fs1 0 nsec
> fn:PASS:mount bpffs /sys/kernel/debug/fs2 0 nsec
> fn:PASS:reading /sys/kernel/debug/fs1/maps.debug 0 nsec
> fn:PASS:reading /sys/kernel/debug/fs2/progs.debug 0 nsec
> fn:PASS:creating /sys/kernel/debug/fs1/a 0 nsec
> fn:PASS:creating /sys/kernel/debug/fs1/a/1 0 nsec
> fn:PASS:creating /sys/kernel/debug/fs1/b 0 nsec
> fn:PASS:create_map(ARRAY) 0 nsec
> fn:PASS:pin map 0 nsec
> fn:PASS:stat(/sys/kernel/debug/fs1/a) 0 nsec
> fn:PASS:renameat2(/fs1/a, /fs1/b, RENAME_EXCHANGE) 0 nsec
> fn:PASS:stat(/sys/kernel/debug/fs1/b) 0 nsec
> fn:PASS:b should have a's inode 0 nsec
> fn:PASS:access(/sys/kernel/debug/fs1/b/1) 0 nsec
> fn:PASS:stat(/sys/kernel/debug/fs1/map) 0 nsec
> fn:PASS:renameat2(/fs1/c, /fs1/b, RENAME_EXCHANGE) 0 nsec
> fn:PASS:stat(/sys/kernel/debug/fs1/b) 0 nsec
> fn:PASS:b should have c's inode 0 nsec
> fn:PASS:access(/sys/kernel/debug/fs1/c/1) 0 nsec
> fn:PASS:renameat2(RENAME_NOREPLACE) 0 nsec
> fn:PASS:access(/sys/kernel/debug/fs1/b) 0 nsec
> bpf_testmod.ko is already unloaded.
> Loading bpf_testmod.ko...
> Successfully loaded bpf_testmod.ko.
> test_test_bpffs:PASS:clone 0 nsec
> test_test_bpffs:PASS:waitpid 0 nsec
> test_test_bpffs:PASS:bpffs test 0 nsec
> #282 test_bpffs:OK
> Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED
> Successfully unloaded bpf_testmod.ko.
>
> [0] https://github.com/danobi/vmtest
>
> Signed-off-by: Manu Bretelle <chantr4@gmail.com>
> ---
> .../selftests/bpf/prog_tests/test_bpffs.c | 28 +++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/test_bpffs.c b/tools/testing/selftests/bpf/prog_tests/test_bpffs.c
> index 214d9f4a94a5..001bf694c269 100644
> --- a/tools/testing/selftests/bpf/prog_tests/test_bpffs.c
> +++ b/tools/testing/selftests/bpf/prog_tests/test_bpffs.c
> @@ -3,12 +3,14 @@
> #define _GNU_SOURCE
> #include <stdio.h>
> #include <sched.h>
> +#include <mntent.h>
> #include <sys/mount.h>
> #include <sys/stat.h>
> #include <sys/types.h>
> #include <test_progs.h>
>
> #define TDIR "/sys/kernel/debug"
> +#define MTAB "/etc/mtab"
>
> static int read_iter(char *file)
> {
> @@ -32,6 +34,8 @@ static int read_iter(char *file)
>
> static int fn(void)
> {
> + /* A buffer to store logging messages */
> + char buf[1024];
> struct stat a, b, c;
> int err, map;
>
> @@ -43,6 +47,30 @@ static int fn(void)
> if (!ASSERT_OK(err, "mount /"))
> goto out;
>
> + /* TDIR may have mounts below. unount them first */
> + FILE *mtab = setmntent(MTAB, "r");
> +
> + if (!ASSERT_TRUE(mtab != NULL, "accessing " MTAB)) {
> + err = errno;
> + goto out;
> + }
> +
> + struct mntent *mnt = NULL;
> +
> + while ((mnt = getmntent(mtab)) != NULL) {
> + if (strlen(mnt->mnt_dir) > strlen(TDIR) &&
> + strncmp(TDIR, mnt->mnt_dir, strlen(TDIR)) == 0) {
> + snprintf(buf, sizeof(buf) - 1, "umount %s", mnt->mnt_dir);
> + err = umount(mnt->mnt_dir);
> + if (!ASSERT_OK(err, buf)) {
> + endmntent(mtab);
> + goto out;
> + }
> + }
> + }
> + // Ignore any error here
> + endmntent(mtab);
> +
> err = umount(TDIR);
> if (!ASSERT_OK(err, "umount " TDIR))
> goto out;
next prev parent reply other threads:[~2023-10-24 21:29 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-24 20:18 [PATCH bpf-next] selftests/bpf: umount children of TDIR in test_bpffs Manu Bretelle
2023-10-24 21:29 ` Kui-Feng Lee [this message]
2023-10-25 5:41 ` Manu Bretelle
2023-10-26 21:35 ` Alexei Starovoitov
2023-10-28 0:56 ` Manu Bretelle
2023-10-27 6:08 ` Yonghong Song
2023-10-27 21:09 ` Manu Bretelle
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