Re: [PATCH] selftests: add binderfs selftests

[Christian Brauner]

On Wed, Jan 16, 2019 at 06:57:10PM +0200, Christian Brauner wrote:
> On January 16, 2019 6:42:20 PM GMT+02:00, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> >On Wed, Jan 16, 2019 at 06:21:12PM +0200, Christian Brauner wrote:
> >> On January 16, 2019 5:54:50 PM GMT+02:00, Greg KH
> ><gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> >> >On Wed, Jan 16, 2019 at 02:19:03PM +0100, Christian Brauner wrote:
> >> >> This adds the promised selftest for binderfs. It will verify the
> >> >following
> >> >> things:
> >> >> - binderfs mounting works
> >> >> - binder device allocation works
> >> >> - performing a binder ioctl() request through a binderfs device
> >works
> >> >> - binder device removal works
> >> >> - binder-control removal fails
> >> >> - binderfs unmounting works
> >> >> 
> >> >> Cc: Todd Kjos <tkjos@xxxxxxxxxx>
> >> >> Signed-off-by: Christian Brauner <christian.brauner@xxxxxxxxxx>
> >> >> ---
> >> >>  tools/testing/selftests/Makefile              |   1 +
> >> >>  .../selftests/filesystems/binderfs/.gitignore |   1 +
> >> >>  .../selftests/filesystems/binderfs/Makefile   |   6 +
> >> >>  .../filesystems/binderfs/binderfs_test.c      | 120
> >> >++++++++++++++++++
> >> >>  .../selftests/filesystems/binderfs/config     |   3 +
> >> >>  5 files changed, 131 insertions(+)
> >> >>  create mode 100644
> >> >tools/testing/selftests/filesystems/binderfs/.gitignore
> >> >>  create mode 100644
> >> >tools/testing/selftests/filesystems/binderfs/Makefile
> >> >>  create mode 100644
> >> >tools/testing/selftests/filesystems/binderfs/binderfs_test.c
> >> >>  create mode 100644
> >> >tools/testing/selftests/filesystems/binderfs/config
> >> >> 
> >> >> diff --git a/tools/testing/selftests/Makefile
> >> >b/tools/testing/selftests/Makefile
> >> >> index 1a2bd15c5b6e..400ee81a3043 100644
> >> >> --- a/tools/testing/selftests/Makefile
> >> >> +++ b/tools/testing/selftests/Makefile
> >> >> @@ -10,6 +10,7 @@ TARGETS += drivers/dma-buf
> >> >>  TARGETS += efivarfs
> >> >>  TARGETS += exec
> >> >>  TARGETS += filesystems
> >> >> +TARGETS += filesystems/binderfs
> >> >>  TARGETS += firmware
> >> >>  TARGETS += ftrace
> >> >>  TARGETS += futex
> >> >> diff --git
> >a/tools/testing/selftests/filesystems/binderfs/.gitignore
> >> >b/tools/testing/selftests/filesystems/binderfs/.gitignore
> >> >> new file mode 100644
> >> >> index 000000000000..8a5d9bf63dd4
> >> >> --- /dev/null
> >> >> +++ b/tools/testing/selftests/filesystems/binderfs/.gitignore
> >> >> @@ -0,0 +1 @@
> >> >> +binderfs_test
> >> >> diff --git a/tools/testing/selftests/filesystems/binderfs/Makefile
> >> >b/tools/testing/selftests/filesystems/binderfs/Makefile
> >> >> new file mode 100644
> >> >> index 000000000000..58cb659b56b4
> >> >> --- /dev/null
> >> >> +++ b/tools/testing/selftests/filesystems/binderfs/Makefile
> >> >> @@ -0,0 +1,6 @@
> >> >> +# SPDX-License-Identifier: GPL-2.0
> >> >> +
> >> >> +CFLAGS += -I../../../../../usr/include/
> >> >> +TEST_GEN_PROGS := binderfs_test
> >> >> +
> >> >> +include ../../lib.mk
> >> >> diff --git
> >> >a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
> >> >b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
> >> >> new file mode 100644
> >> >> index 000000000000..ca4d9b616e84
> >> >> --- /dev/null
> >> >> +++ b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
> >> >> @@ -0,0 +1,120 @@
> >> >> +// SPDX-License-Identifier: GPL-2.0
> >> >> +
> >> >> +#define _GNU_SOURCE
> >> >> +#include <errno.h>
> >> >> +#include <fcntl.h>
> >> >> +#include <sched.h>
> >> >> +#include <stdio.h>
> >> >> +#include <stdlib.h>
> >> >> +#include <string.h>
> >> >> +#include <sys/ioctl.h>
> >> >> +#include <sys/mount.h>
> >> >> +#include <sys/stat.h>
> >> >> +#include <sys/types.h>
> >> >> +#include <unistd.h>
> >> >> +#include <linux/android/binder.h>
> >> >> +#include <linux/android/binderfs.h>
> >> >> +#include "../../kselftest.h"
> >> >> +
> >> >> +int main(int argc, char *argv[])
> >> >> +{
> >> >> +	int fd, ret, saved_errno;
> >> >> +	size_t len;
> >> >> +	struct binderfs_device device = { 0 };
> >> >> +	struct binder_version version = { 0 };
> >> >> +
> >> >> +	ret = unshare(CLONE_NEWNS);
> >> >> +	if (ret < 0)
> >> >> +		ksft_exit_fail_msg("%s - Failed to unshare mount namespace\n",
> >> >> +				   strerror(errno));
> >> >> +
> >> >> +	ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
> >> >> +	if (ret < 0)
> >> >> +		ksft_exit_fail_msg("%s - Failed to mount / as private\n",
> >> >> +				   strerror(errno));
> >> >> +
> >> >> +	ret = mkdir("/dev/binderfs", 0755);
> >> >> +	if (ret < 0 && errno != EEXIST)
> >> >> +		ksft_exit_fail_msg(
> >> >> +			"%s - Failed to create binderfs mountpoint\n",
> >> >> +			strerror(errno));
> >> >> +
> >> >> +	ret = mount(NULL, "/dev/binderfs", "binder", 0, 0);
> >> >> +	if (ret < 0)
> >> >> +		ksft_exit_fail_msg("%s - Failed to mount binderfs\n",
> >> >> +				   strerror(errno));
> >> >
> >> >Can you check first to see if the kernel under test really even has
> >> >binderfs in it?  If not, you need to just
> >> 
> >> Hm, I thought that's what the "config" file was for?
> >> E.g. a conditional compile or is this just a hint to the
> >> user what's needed to run the test?
> >
> >I do not know.  What happens if you try to run this test on a kernel
> >without that config option?  Does it not work as the framework
> >correctly
> >detects this?
> 
> I did test and it worked fine but let me check by setting up a clean vm and retry.

The compile always happens and always succeeds but the test will fail if
run on a kernel that does not have binderfs. So the mount() call should
check for ret == ENODEV and then exit with skip.

Thanks!
Christian