On Tue, Oct 24, 2023 at 02:29:19PM -0700, Kui-Feng Lee wrote:
>
>
> 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>/"?
>
Fair point, I suppose we would want to keep TDIR a defined string as it does
simplify the gymnastic involved through the rest of the script, but yeah
looking at the original commit:
edb65ee5aa25 (selftests/bpf: Add bpffs preload test)
I don't see any reason to use an alternate directory and rather mkdir it vs
umounting the original one.
so something like
#define TDIR "/sys/kernel/test_bpffs"
Would probably do.
Alexei could confirm his original intent probably.
> >
> > 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@xxxxxxxxx>
> > ---
> > .../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;
