linux.git/tools/testing/selftests/pidfd, branch v5.10-rc2

Merge tag 'threads-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

2020-10-14T21:39:20+00:00

Pull pidfd updates from Christian Brauner:
 "This introduces a new extension to the pidfd_open() syscall. Users can
  now raise the new PIDFD_NONBLOCK flag to support non-blocking pidfd
  file descriptors. This has been requested for uses in async process
  management libraries such as async-pidfd in Rust.

  Ever since the introduction of pidfds and more advanced async io
  various programming languages such as Rust have grown support for
  async event libraries. These libraries are created to help build
  epoll-based event loops around file descriptors. A common pattern is
  to automatically make all file descriptors they manage to O_NONBLOCK.

  For such libraries the EAGAIN error code is treated specially. When a
  function is called that returns EAGAIN the function isn't called again
  until the event loop indicates the the file descriptor is ready.
  Supporting EAGAIN when waiting on pidfds makes such libraries just
  work with little effort.

  This introduces a new flag PIDFD_NONBLOCK that is equivalent to
  O_NONBLOCK. This follows the same patterns we have for other (anon
  inode) file descriptors such as EFD_NONBLOCK, IN_NONBLOCK,
  SFD_NONBLOCK, TFD_NONBLOCK and the same for close-on-exec flags.

  Passing a non-blocking pidfd to waitid() currently has no effect, i.e.
  is not supported. There are users which would like to use waitid() on
  pidfds that are O_NONBLOCK and mix it with pidfds that are blocking
  and both pass them to waitid().

  The expected behavior is to have waitid() return -EAGAIN for
  non-blocking pidfds and to block for blocking pidfds without needing
  to perform any additional checks for flags set on the pidfd before
  passing it to waitid(). Non-blocking pidfds will return EAGAIN from
  waitid() when no child process is ready yet. Returning -EAGAIN for
  non-blocking pidfds makes it easier for event loops that handle EAGAIN
  specially.

  It also makes the API more consistent and uniform. In essence,
  waitid() is treated like a read on a non-blocking pidfd or a recvmsg()
  on a non-blocking socket.

  With the addition of support for non-blocking pidfds we support the
  same functionality that sockets do. For sockets() recvmsg() supports
  MSG_DONTWAIT for pidfds waitid() supports WNOHANG. Both flags are
  per-call options. In contrast non-blocking pidfds and non-blocking
  sockets are a setting on an open file description affecting all
  threads in the calling process as well as other processes that hold
  file descriptors referring to the same open file description. Both
  behaviors, per call and per open file description, have genuine
  use-cases.

  The interaction with the WNOHANG flag is documented as follows:

   - If a non-blocking pidfd is passed and WNOHANG is not raised we
     simply raise the WNOHANG flag internally. When do_wait() returns
     indicating that there are eligible child processes but none have
     exited yet we set EAGAIN. If no child process exists we continue
     returning ECHILD.

   - If a non-blocking pidfd is passed and WNOHANG is raised waitid()
     will continue returning 0, i.e. it will not set EAGAIN. This ensure
     backwards compatibility with applications passing WNOHANG
     explicitly with pidfds"

* tag 'threads-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  tests: remove O_NONBLOCK before waiting for WSTOPPED
  tests: add waitid() tests for non-blocking pidfds
  tests: port pidfd_wait to kselftest harness
  pidfd: support PIDFD_NONBLOCK in pidfd_open()
  exit: support non-blocking pidfds

tests: remove O_NONBLOCK before waiting for WSTOPPED

2020-10-09T09:56:51+00:00

Naresh reported that selftests: pidfd: pidfd_wait hangs on linux next kernel on
x86_64, i386 and arm64 Juno-r2
These devices are using NFS mounted rootfs.
I have tested pidfd testcases independently and all test PASS.

The Hang or exit from test run noticed when run by run_kselftest.sh

pidfd_wait.c:208:wait_nonblock:Expected sys_waitid(P_PIDFD, pidfd,
&info, WSTOPPED, NULL) (-1) == 0 (0)
wait_nonblock: Test terminated by assertion

metadata:
  git branch: master
  git repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
  git commit: e64997027d5f171148687e58b78c8b3c869a6158
  git describe: next-20200922
  make_kernelversion: 5.9.0-rc6
  kernel-config:
http://snapshots.linaro.org/openembedded/lkft/lkft/sumo/intel-core2-32/lkft/linux-next/865/config

The reason for this is a simple race in the selftests, that I overlooked and
which is more likely to hit when there's a lot of processes running on the
system. Basically the child process hasn't SIGSTOPed itself yet but the parent
is already calling waitid() on a O_NONBLOCK pidfd. Since it doesn't find a
WSTOPPED process it returns -EAGAIN correctly.

The fix for this is to move the line where we're removing the O_NONBLOCK
property from the fd before the waitid() WSTOPPED call so we hang until the
child becomes stopped.

Fixes: cd89597bbe5a ("tests: add waitid() tests for non-blocking pidfds")
Reported-by: Naresh Kamboju 
Tested-by: Naresh Kamboju 
Link: https://lkft.validation.linaro.org/scheduler/job/1813223
Signed-off-by: Christian Brauner

selftests/clone3: Avoid OS-defined clone_args

2020-10-08T20:17:25+00:00

As the UAPI headers start to appear in distros, we need to avoid
outdated versions of struct clone_args to be able to test modern
features, named "struct __clone_args". Additionally update the struct
size macro names to match UAPI names.

Acked-by: Christian Brauner 
Link: https://lore.kernel.org/lkml/20200921075432.u4gis3s2o5qrsb5g@wittgenstein/
Signed-off-by: Kees Cook

tests: add waitid() tests for non-blocking pidfds

2020-09-04T11:48:57+00:00

Verify that the PIDFD_NONBLOCK flag works with pidfd_open() and that
waitid() with a non-blocking pidfd returns EAGAIN:

	TAP version 13
	1..3
	# Starting 3 tests from 1 test cases.
	#  RUN           global.wait_simple ...
	#            OK  global.wait_simple
	ok 1 global.wait_simple
	#  RUN           global.wait_states ...
	#            OK  global.wait_states
	ok 2 global.wait_states
	#  RUN           global.wait_nonblock ...
	#            OK  global.wait_nonblock
	ok 3 global.wait_nonblock
	# PASSED: 3 / 3 tests passed.
	# Totals: pass:3 fail:0 xfail:0 xpass:0 skip:0 error:0

Signed-off-by: Christian Brauner 
Reviewed-by: Josh Triplett 
Cc: Shuah Khan 
Cc: linux-kselftest@vger.kernel.org
Link: https://lore.kernel.org/r/20200902102130.147672-5-christian.brauner@ubuntu.com

tests: port pidfd_wait to kselftest harness

2020-09-04T10:34:50+00:00

All of the new pidfd selftests already use the new kselftest harness
infrastructure. It makes for clearer output, makes the code easier to
understand, and makes adding new tests way simpler.

Signed-off-by: Christian Brauner 
Reviewed-by: Josh Triplett 
Cc: Shuah Khan 
Cc: linux-kselftest@vger.kernel.org
Link: https://lore.kernel.org/r/20200902102130.147672-4-christian.brauner@ubuntu.com

Merge tag 'linux-kselftest-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

2020-08-05T17:28:25+00:00

Pull kselftest updates form Shuah Khan:

 - TAP output reporting related fixes from Paolo Bonzini and Kees Cook.

   These fixes make it skip reporting consistent with TAP format.

 - Cleanup fixes to framework run_tests from Yauheni Kaliuta

* tag 'linux-kselftest-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (23 commits)
  selftests/harness: Limit step counter reporting
  selftests/seccomp: Check ENOSYS under tracing
  selftests/seccomp: Refactor to use fixture variants
  selftests/harness: Clean up kern-doc for fixtures
  selftests: kmod: Add module address visibility test
  Replace HTTP links with HTTPS ones: KMOD KERNEL MODULE LOADER - USERMODE HELPER
  selftests: fix condition in run_tests
  selftests: do not use .ONESHELL
  selftests: pidfd: skip test if unshare fails with EPERM
  selftests: pidfd: do not use ksft_exit_skip after ksft_set_plan
  selftests/harness: Report skip reason
  selftests/harness: Display signed values correctly
  selftests/harness: Refactor XFAIL into SKIP
  selftests/harness: Switch to TAP output
  selftests: Add header documentation and helpers
  selftests/binderfs: Fix harness API usage
  selftests: Remove unneeded selftest API headers
  selftests/clone3: Reorder reporting output
  selftests: sync_test: do not use ksft_exit_skip after ksft_set_plan
  selftests: sigaltstack: do not use ksft_exit_skip after ksft_set_plan
  ...

tests: add CLONE_NEWTIME setns tests

2020-07-08T09:14:22+00:00

Now that pidfds support CLONE_NEWTIME as well enable testing them in the
setns() testuite.

Signed-off-by: Christian Brauner 
Cc: Serge Hallyn 
Cc: Michael Kerrisk 
Cc: Dmitry Safonov 
Cc: Andrei Vagin 
Link: https://lore.kernel.org/r/20200706154912.3248030-5-christian.brauner@ubuntu.com

selftests: pidfd: skip test if unshare fails with EPERM

2020-07-07T19:28:58+00:00

Similar to how ENOSYS causes a skip if pidfd_send_signal is not present,
we can do the same for unshare if it fails with EPERM.  This way, running
the test without privileges causes four tests to skip but no early bail out.

Acked-by: Christian Brauner 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Shuah Khan

selftests: pidfd: do not use ksft_exit_skip after ksft_set_plan

2020-07-07T19:28:44+00:00

Calling ksft_exit_skip after ksft_set_plan results in executing fewer tests
than planned.  Use ksft_test_result_skip instead.

The plan passed to ksft_set_plan was wrong, too, so fix it while at it.

Acked-by: Christian Brauner 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Shuah Khan

selftests: Remove unneeded selftest API headers

2020-07-06T21:59:07+00:00

Remove unused includes of the kselftest.h header.

Acked-by: Christian Brauner 
Signed-off-by: Kees Cook 
Signed-off-by: Shuah Khan