selftests/pidfd: add pidfs file handle selftests

Add selftests for pidfs file handles.

Link: https://lore.kernel.org/r/20241202-imstande-einsicht-d78753e1c632@brauner
Reviewed-by: Amir Goldstein <a

selftests/pidfd: add pidfs file handle selftests

Add selftests for pidfs file handles.

Link: https://lore.kernel.org/r/20241202-imstande-einsicht-d78753e1c632@brauner
Reviewed-by: Amir Goldstein <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>

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selftests: pidfd: Fix compling warnings

Fix warnings and enable Wall.

pidfd_wait.c: In function ‘wait_nonblock’:
pidfd_wait.c:150:13: warning: unused variable ‘status’ [-Wunused-variable]
150 |

selftests: pidfd: Fix compling warnings

Fix warnings and enable Wall.

pidfd_wait.c: In function ‘wait_nonblock’:
pidfd_wait.c:150:13: warning: unused variable ‘status’ [-Wunused-variable]
150 | int pidfd, status = 0;
| ^~~~~~
...
pidfd_test.c: In function ‘child_poll_exec_test’:
pidfd_test.c:438:1: warning: no return statement in function returning non-void [-Wreturn-type]
438 | }
| ^

Signed-off-by: Li Zhijian <[email protected]>
v2: fix mistake assignment to pidfd
Signed-off-by: Shuah Khan <[email protected]>

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ksefltests: pidfd: Fix wait_states: Test terminated by timeout

0Day/LKP observed that the kselftest blocks forever since one of the
pidfd_wait doesn't terminate in 1 of 30 runs. After digging into
t

ksefltests: pidfd: Fix wait_states: Test terminated by timeout

0Day/LKP observed that the kselftest blocks forever since one of the
pidfd_wait doesn't terminate in 1 of 30 runs. After digging into
the source, we found that it blocks at:
ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WCONTINUED, NULL), 0);

wait_states has below testing flow:
CHILD PARENT
---------------+--------------
1 STOP itself
2 WAIT for CHILD STOPPED
3 SIGNAL CHILD to CONT
4 CONT
5 STOP itself
5' WAIT for CHILD CONT
6 WAIT for CHILD STOPPED

The problem is that the kernel cannot ensure the order of 5 and 5', once
5 goes first, the test will fail.

we can reproduce it by:
$ while true; do make run_tests -C pidfd; done

Introduce a blocking read in child process to make sure the parent can
check its WCONTINUED.

CC: Philip Li <[email protected]>
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Li Zhijian <[email protected]>
Reviewed-by: Christian Brauner (Microsoft) <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests: fix an unused variable warning in pidfd selftest

I fixed a few warnings like this in commit e2aa5e650b07
("selftests: fixup build warnings in pidfd / clone3 tests"), but I
missed this one

selftests: fix an unused variable warning in pidfd selftest

I fixed a few warnings like this in commit e2aa5e650b07
("selftests: fixup build warnings in pidfd / clone3 tests"), but I
missed this one by mistake. Since this variable is unused, remove it.

Signed-off-by: Axel Rasmussen <[email protected]>
Reviewed-by: Christian Brauner <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests: fixup build warnings in pidfd / clone3 tests

These are some trivial fixups, which were needed to build the tests with
clang and -Werror. The following issues are fixed:

- Remove various

selftests: fixup build warnings in pidfd / clone3 tests

These are some trivial fixups, which were needed to build the tests with
clang and -Werror. The following issues are fixed:

- Remove various unused variables.
- In child_poll_leader_exit_test, clang isn't smart enough to realize
syscall(SYS_exit, 0) won't return, so it complains we never return
from a non-void function. Add an extra exit(0) to appease it.
- In test_pidfd_poll_leader_exit, ret may be branched on despite being
uninitialized, if we have !use_waitpid. Initialize it to zero to get
the right behavior in that case.

Signed-off-by: Axel Rasmussen <[email protected]>
Acked-by: Christian Brauner <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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tests: remove O_NONBLOCK before waiting for WSTOPPED

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 mounte

tests: remove O_NONBLOCK before waiting for WSTOPPED

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 <[email protected]>
Tested-by: Naresh Kamboju <[email protected]>
Link: https://lkft.validation.linaro.org/scheduler/job/1813223
Signed-off-by: Christian Brauner <[email protected]>

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

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
# St

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

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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]

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tests: port pidfd_wait to kselftest harness

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

tests: port pidfd_wait to kselftest harness

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 <[email protected]>
Reviewed-by: Josh Triplett <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]

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pidfd: add pidfd_wait tests

Add tests for pidfd_wait() and CLONE_WAIT_PID:
- test that waitid(P_PIDFD) fails on /proc/<pid>
- test that waitid(P_PIDFD) fails on /dev/null
- test that waitid(P_PIDFD)

pidfd: add pidfd_wait tests

Add tests for pidfd_wait() and CLONE_WAIT_PID:
- test that waitid(P_PIDFD) fails on /proc/<pid>
- test that waitid(P_PIDFD) fails on /dev/null
- test that waitid(P_PIDFD) can wait on a pidfd
- test that waitid(P_PIDFD) can wait on a pidfd and return siginfo_t
- test that waitid(P_PIDFD) works with WEXITED
- test that waitid(P_PIDFD) works with WSTOPPED
- test that waitid(P_PIDFD) works with WUNTRACED
- test that waitid(P_PIDFD) works with WCONTINUED
- test that waitid(P_PIDFD) works with WNOWAIT
- test that waitid(P_PIDFD)works with WNOHANG

Signed-off-by: Christian Brauner <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: "Eric W. Biederman" <[email protected]>
Cc: Joel Fernandes (Google) <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: David Howells <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Andy Lutomirsky <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Aleksa Sarai <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Al Viro <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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