diff mbox series

[v4,4/4] selftests: pidfd: add tests for PIDFD_SELF_*

Message ID b9851fa9f87d22f352f960b847d99459ef7d74a1.1729198898.git.lorenzo.stoakes@oracle.com (mailing list archive)
State New
Headers show
Series introduce PIDFD_SELF* sentinels | expand

Commit Message

Lorenzo Stoakes Oct. 17, 2024, 9:05 p.m. UTC 
Add tests to assert that PIDFD_SELF_* correctly refers to the current
thread and process.

This is only practically meaningful to pidfd_send_signal() and
pidfd_getfd(), but also explicitly test that we disallow this feature for
setns() where it would make no sense.

We cannot reasonably wait on ourself using waitid(P_PIDFD, ...) so while in
theory PIDFD_SELF_* would work here, we'd be left blocked if we tried it.

We defer testing of mm-specific functionality which uses pidfd, namely
process_madvise() and process_mrelease() to mm testing (though note the
latter can not be sensibly tested as it would require the testing process
to be dying).

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
---
 tools/testing/selftests/pidfd/pidfd.h         |   2 +
 .../selftests/pidfd/pidfd_getfd_test.c        | 141 ++++++++++++++++++
 .../selftests/pidfd/pidfd_setns_test.c        |  11 ++
 tools/testing/selftests/pidfd/pidfd_test.c    |  76 ++++++++--
 4 files changed, 218 insertions(+), 12 deletions(-)

Comments

kernel test robot Oct. 25, 2024, 8:10 a.m. UTC | #1 
Hello,

kernel test robot noticed "kernel-selftests.cgroup.make.fail" on:

commit: 930cb1423ee2522760ffde43455b14df5c0d5487 ("[PATCH v4 4/4] selftests: pidfd: add tests for PIDFD_SELF_*")
url: https://github.com/intel-lab-lkp/linux/commits/Lorenzo-Stoakes/pidfd-extend-pidfd_get_pid-and-de-duplicate-pid-lookup/20241018-050825
base: https://git.kernel.org/cgit/linux/kernel/git/shuah/linux-kselftest.git next
patch link: https://lore.kernel.org/all/b9851fa9f87d22f352f960b847d99459ef7d74a1.1729198898.git.lorenzo.stoakes@oracle.com/
patch subject: [PATCH v4 4/4] selftests: pidfd: add tests for PIDFD_SELF_*

in testcase: kernel-selftests
version: kernel-selftests-x86_64-977d51cf-1_20240508
with following parameters:

	group: cgroup



config: x86_64-rhel-8.3-kselftests
compiler: gcc-12
test machine: 36 threads 1 sockets Intel(R) Core(TM) i9-10980XE CPU @ 3.00GHz (Cascade Lake) with 32G memory

(please refer to attached dmesg/kmsg for entire log/backtrace)




If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202410251504.707d78fc-oliver.sang@intel.com

KERNEL SELFTESTS: linux_headers_dir is /usr/src/linux-headers-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487
'/usr/sbin/iptables' -> '/usr/sbin/iptables-nft'
'/usr/sbin/iptables-restore' -> '/usr/sbin/iptables-nft-restore'
'/usr/sbin/iptables-save' -> '/usr/sbin/iptables-nft-save'
'/usr/sbin/ip6tables' -> '/usr/sbin/ip6tables-nft'
'/usr/sbin/ip6tables-restore' -> '/usr/sbin/ip6tables-nft-restore'
'/usr/sbin/ip6tables-save' -> '/usr/sbin/ip6tables-nft-save'
2024-10-23 12:53:55 sed -i s/default_timeout=45/default_timeout=300/ kselftest/runner.sh
2024-10-23 12:53:55 make -j36 -C cgroup
make: Entering directory '/usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487/tools/testing/selftests/cgroup'
  CC       test_core
  CC       test_cpu
  CC       test_cpuset
  CC       test_freezer
  CC       test_hugetlb_memcg
  CC       test_kill
  CC       test_kmem
  CC       test_memcontrol
  CC       test_pids
  CC       test_zswap
  CC       wait_inotify
In file included from /usr/x86_64-linux-gnu/include/asm/fcntl.h:1,
                 from /usr/x86_64-linux-gnu/include/linux/fcntl.h:5,
                 from /usr/x86_64-linux-gnu/include/linux/pidfd.h:7,
                 from ../pidfd/pidfd.h:19,
                 from test_kill.c:13:
/usr/x86_64-linux-gnu/include/asm-generic/fcntl.h:156:8: error: redefinition of ‘struct f_owner_ex’
  156 | struct f_owner_ex {
      |        ^~~~~~~~~~
In file included from /usr/include/x86_64-linux-gnu/bits/fcntl.h:61,
                 from /usr/include/fcntl.h:35,
                 from ../pidfd/pidfd.h:8:
/usr/include/x86_64-linux-gnu/bits/fcntl-linux.h:274:8: note: originally defined here
  274 | struct f_owner_ex
      |        ^~~~~~~~~~
/usr/x86_64-linux-gnu/include/asm-generic/fcntl.h:196:8: error: redefinition of ‘struct flock’
  196 | struct flock {
      |        ^~~~~
/usr/include/x86_64-linux-gnu/bits/fcntl.h:35:8: note: originally defined here
   35 | struct flock
      |        ^~~~~
/usr/x86_64-linux-gnu/include/asm-generic/fcntl.h:210:8: error: redefinition of ‘struct flock64’
  210 | struct flock64 {
      |        ^~~~~~~
/usr/include/x86_64-linux-gnu/bits/fcntl.h:50:8: note: originally defined here
   50 | struct flock64
      |        ^~~~~~~
make: *** [../lib.mk:221: /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487/tools/testing/selftests/cgroup/test_kill] Error 1
make: *** Waiting for unfinished jobs....
make: Leaving directory '/usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487/tools/testing/selftests/cgroup'
2024-10-23 12:53:56 make quicktest=1 run_tests -C cgroup
make: Entering directory '/usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487/tools/testing/selftests/cgroup'
  CC       test_kill
In file included from /usr/x86_64-linux-gnu/include/asm/fcntl.h:1,
                 from /usr/x86_64-linux-gnu/include/linux/fcntl.h:5,
                 from /usr/x86_64-linux-gnu/include/linux/pidfd.h:7,
                 from ../pidfd/pidfd.h:19,
                 from test_kill.c:13:
/usr/x86_64-linux-gnu/include/asm-generic/fcntl.h:156:8: error: redefinition of ‘struct f_owner_ex’
  156 | struct f_owner_ex {
      |        ^~~~~~~~~~
In file included from /usr/include/x86_64-linux-gnu/bits/fcntl.h:61,
                 from /usr/include/fcntl.h:35,
                 from ../pidfd/pidfd.h:8:
/usr/include/x86_64-linux-gnu/bits/fcntl-linux.h:274:8: note: originally defined here
  274 | struct f_owner_ex
      |        ^~~~~~~~~~
/usr/x86_64-linux-gnu/include/asm-generic/fcntl.h:196:8: error: redefinition of ‘struct flock’
  196 | struct flock {
      |        ^~~~~
/usr/include/x86_64-linux-gnu/bits/fcntl.h:35:8: note: originally defined here
   35 | struct flock
      |        ^~~~~
/usr/x86_64-linux-gnu/include/asm-generic/fcntl.h:210:8: error: redefinition of ‘struct flock64’
  210 | struct flock64 {
      |        ^~~~~~~
/usr/include/x86_64-linux-gnu/bits/fcntl.h:50:8: note: originally defined here
   50 | struct flock64
      |        ^~~~~~~
make: *** [../lib.mk:222: /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487/tools/testing/selftests/cgroup/test_kill] Error 1
make: Leaving directory '/usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487/tools/testing/selftests/cgroup'



The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20241025/202410251504.707d78fc-oliver.sang@intel.com
Lorenzo Stoakes Oct. 25, 2024, 8:48 a.m. UTC | #2 
On Fri, Oct 25, 2024 at 04:10:37PM +0800, kernel test robot wrote:
>
>
> Hello,
>
> kernel test robot noticed "kernel-selftests.cgroup.make.fail" on:
>
> commit: 930cb1423ee2522760ffde43455b14df5c0d5487 ("[PATCH v4 4/4] selftests: pidfd: add tests for PIDFD_SELF_*")
> url: https://github.com/intel-lab-lkp/linux/commits/Lorenzo-Stoakes/pidfd-extend-pidfd_get_pid-and-de-duplicate-pid-lookup/20241018-050825

Thanks.

This issue is because, incredibly, the cgroup tests import ../pidfd/pidfd.h
solely to use a helper, but in doing so inadvertently pull in linux/pidfd.h
_without_ the tools wrapper.

Adding a tools wrapper to cgroup fails too because of some other dependency.

I will separate out a header with this helper in it to work around this and
respin.

A gentle point on this - in my view, adding/updating tests shouldn't hold up a
series, rather we should do everything we can to encourage kernel developers to
add/expand tests.

So I'd say, in future, it might be best - if the tests already do something
considered 'bad' - to defer fixing that badness to a dedicated series, rather
than forcing an unrelated one to have to include commits to fixup pre-existing
problems like this.

I don't think anyone is really going to understand why a PIDFD_SELF series is
touching a cgroup test at this point.

Thanks!

> base: https://git.kernel.org/cgit/linux/kernel/git/shuah/linux-kselftest.git next
> patch link: https://lore.kernel.org/all/b9851fa9f87d22f352f960b847d99459ef7d74a1.1729198898.git.lorenzo.stoakes@oracle.com/
> patch subject: [PATCH v4 4/4] selftests: pidfd: add tests for PIDFD_SELF_*
>
> in testcase: kernel-selftests
> version: kernel-selftests-x86_64-977d51cf-1_20240508
> with following parameters:
>
> 	group: cgroup
>
>
>
> config: x86_64-rhel-8.3-kselftests
> compiler: gcc-12
> test machine: 36 threads 1 sockets Intel(R) Core(TM) i9-10980XE CPU @ 3.00GHz (Cascade Lake) with 32G memory
>
> (please refer to attached dmesg/kmsg for entire log/backtrace)
>
>
>
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <oliver.sang@intel.com>
> | Closes: https://lore.kernel.org/oe-lkp/202410251504.707d78fc-oliver.sang@intel.com
>
> KERNEL SELFTESTS: linux_headers_dir is /usr/src/linux-headers-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487
> '/usr/sbin/iptables' -> '/usr/sbin/iptables-nft'
> '/usr/sbin/iptables-restore' -> '/usr/sbin/iptables-nft-restore'
> '/usr/sbin/iptables-save' -> '/usr/sbin/iptables-nft-save'
> '/usr/sbin/ip6tables' -> '/usr/sbin/ip6tables-nft'
> '/usr/sbin/ip6tables-restore' -> '/usr/sbin/ip6tables-nft-restore'
> '/usr/sbin/ip6tables-save' -> '/usr/sbin/ip6tables-nft-save'
> 2024-10-23 12:53:55 sed -i s/default_timeout=45/default_timeout=300/ kselftest/runner.sh
> 2024-10-23 12:53:55 make -j36 -C cgroup
> make: Entering directory '/usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487/tools/testing/selftests/cgroup'
>   CC       test_core
>   CC       test_cpu
>   CC       test_cpuset
>   CC       test_freezer
>   CC       test_hugetlb_memcg
>   CC       test_kill
>   CC       test_kmem
>   CC       test_memcontrol
>   CC       test_pids
>   CC       test_zswap
>   CC       wait_inotify
> In file included from /usr/x86_64-linux-gnu/include/asm/fcntl.h:1,
>                  from /usr/x86_64-linux-gnu/include/linux/fcntl.h:5,
>                  from /usr/x86_64-linux-gnu/include/linux/pidfd.h:7,
>                  from ../pidfd/pidfd.h:19,
>                  from test_kill.c:13:
> /usr/x86_64-linux-gnu/include/asm-generic/fcntl.h:156:8: error: redefinition of ‘struct f_owner_ex’
>   156 | struct f_owner_ex {
>       |        ^~~~~~~~~~
> In file included from /usr/include/x86_64-linux-gnu/bits/fcntl.h:61,
>                  from /usr/include/fcntl.h:35,
>                  from ../pidfd/pidfd.h:8:
> /usr/include/x86_64-linux-gnu/bits/fcntl-linux.h:274:8: note: originally defined here
>   274 | struct f_owner_ex
>       |        ^~~~~~~~~~
> /usr/x86_64-linux-gnu/include/asm-generic/fcntl.h:196:8: error: redefinition of ‘struct flock’
>   196 | struct flock {
>       |        ^~~~~
> /usr/include/x86_64-linux-gnu/bits/fcntl.h:35:8: note: originally defined here
>    35 | struct flock
>       |        ^~~~~
> /usr/x86_64-linux-gnu/include/asm-generic/fcntl.h:210:8: error: redefinition of ‘struct flock64’
>   210 | struct flock64 {
>       |        ^~~~~~~
> /usr/include/x86_64-linux-gnu/bits/fcntl.h:50:8: note: originally defined here
>    50 | struct flock64
>       |        ^~~~~~~
> make: *** [../lib.mk:221: /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487/tools/testing/selftests/cgroup/test_kill] Error 1
> make: *** Waiting for unfinished jobs....
> make: Leaving directory '/usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487/tools/testing/selftests/cgroup'
> 2024-10-23 12:53:56 make quicktest=1 run_tests -C cgroup
> make: Entering directory '/usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487/tools/testing/selftests/cgroup'
>   CC       test_kill
> In file included from /usr/x86_64-linux-gnu/include/asm/fcntl.h:1,
>                  from /usr/x86_64-linux-gnu/include/linux/fcntl.h:5,
>                  from /usr/x86_64-linux-gnu/include/linux/pidfd.h:7,
>                  from ../pidfd/pidfd.h:19,
>                  from test_kill.c:13:
> /usr/x86_64-linux-gnu/include/asm-generic/fcntl.h:156:8: error: redefinition of ‘struct f_owner_ex’
>   156 | struct f_owner_ex {
>       |        ^~~~~~~~~~
> In file included from /usr/include/x86_64-linux-gnu/bits/fcntl.h:61,
>                  from /usr/include/fcntl.h:35,
>                  from ../pidfd/pidfd.h:8:
> /usr/include/x86_64-linux-gnu/bits/fcntl-linux.h:274:8: note: originally defined here
>   274 | struct f_owner_ex
>       |        ^~~~~~~~~~
> /usr/x86_64-linux-gnu/include/asm-generic/fcntl.h:196:8: error: redefinition of ‘struct flock’
>   196 | struct flock {
>       |        ^~~~~
> /usr/include/x86_64-linux-gnu/bits/fcntl.h:35:8: note: originally defined here
>    35 | struct flock
>       |        ^~~~~
> /usr/x86_64-linux-gnu/include/asm-generic/fcntl.h:210:8: error: redefinition of ‘struct flock64’
>   210 | struct flock64 {
>       |        ^~~~~~~
> /usr/include/x86_64-linux-gnu/bits/fcntl.h:50:8: note: originally defined here
>    50 | struct flock64
>       |        ^~~~~~~
> make: *** [../lib.mk:222: /usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487/tools/testing/selftests/cgroup/test_kill] Error 1
> make: Leaving directory '/usr/src/perf_selftests-x86_64-rhel-8.3-kselftests-930cb1423ee2522760ffde43455b14df5c0d5487/tools/testing/selftests/cgroup'
>
>
>
> The kernel config and materials to reproduce are available at:
> https://download.01.org/0day-ci/archive/20241025/202410251504.707d78fc-oliver.sang@intel.com
>
>
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
>
diff mbox series

Patch

diff --git a/tools/testing/selftests/pidfd/pidfd.h b/tools/testing/selftests/pidfd/pidfd.h
index 88d6830ee004..cbe1a2be3cec 100644
--- a/tools/testing/selftests/pidfd/pidfd.h
+++ b/tools/testing/selftests/pidfd/pidfd.h
@@ -16,6 +16,8 @@ 
 #include <sys/types.h>
 #include <sys/wait.h>
 
+#include <linux/pidfd.h>
+
 #include "../kselftest.h"
 
 #ifndef P_PIDFD
diff --git a/tools/testing/selftests/pidfd/pidfd_getfd_test.c b/tools/testing/selftests/pidfd/pidfd_getfd_test.c
index cd51d547b751..48d224b13c01 100644
--- a/tools/testing/selftests/pidfd/pidfd_getfd_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_getfd_test.c
@@ -6,6 +6,7 @@ 
 #include <limits.h>
 #include <linux/types.h>
 #include <poll.h>
+#include <pthread.h>
 #include <sched.h>
 #include <signal.h>
 #include <stdio.h>
@@ -15,6 +16,7 @@ 
 #include <sys/prctl.h>
 #include <sys/wait.h>
 #include <unistd.h>
+#include <sys/mman.h>
 #include <sys/socket.h>
 #include <linux/kcmp.h>
 
@@ -114,6 +116,94 @@  static int child(int sk)
 	return ret;
 }
 
+static int __pidfd_self_thread_worker(unsigned long page_size)
+{
+	int memfd;
+	int newfd;
+	char *ptr;
+	int err = 0;
+
+	/*
+	 * Unshare our FDs so we have our own set. This means
+	 * PIDFD_SELF_THREAD_GROUP will fal.
+	 */
+	if (unshare(CLONE_FILES) < 0) {
+		err = -errno;
+		goto exit;
+	}
+
+	/* Truncate, map in and write to our memfd. */
+	memfd = sys_memfd_create("test_self_child", 0);
+	if (memfd < 0) {
+		err = -errno;
+		goto exit;
+	}
+
+	if (ftruncate(memfd, page_size)) {
+		err = -errno;
+		goto exit_close_memfd;
+	}
+
+	ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
+		   MAP_SHARED, memfd, 0);
+	if (ptr == MAP_FAILED) {
+		err = -errno;
+		goto exit_close_memfd;
+	}
+	ptr[0] = 'y';
+	if (munmap(ptr, page_size)) {
+		err = -errno;
+		goto exit_close_memfd;
+	}
+
+	/* Get a thread-local duplicate of our memfd. */
+	newfd = sys_pidfd_getfd(PIDFD_SELF_THREAD, memfd, 0);
+	if (newfd < 0) {
+		err = -errno;
+		goto exit_close_memfd;
+	}
+
+	if (memfd == newfd) {
+		err = -EINVAL;
+		goto exit_close_fds;
+	}
+
+	/* Map in new fd and make sure that the data is as expected. */
+	ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
+		   MAP_SHARED, newfd, 0);
+	if (ptr == MAP_FAILED) {
+		err = -errno;
+		goto exit_close_fds;
+	}
+
+	if (ptr[0] != 'y') {
+		err = -EINVAL;
+		goto exit_close_fds;
+	}
+
+	if (munmap(ptr, page_size)) {
+		err = -errno;
+		goto exit_close_fds;
+	}
+
+exit_close_fds:
+	close(newfd);
+exit_close_memfd:
+	close(memfd);
+exit:
+	return err;
+}
+
+static void *pidfd_self_thread_worker(void *arg)
+{
+	unsigned long page_size = (unsigned long)arg;
+	int ret;
+
+	/* We forward any errors for the caller to handle. */
+	ret = __pidfd_self_thread_worker(page_size);
+	return (void *)(intptr_t)ret;
+}
+
 FIXTURE(child)
 {
 	/*
@@ -264,6 +354,57 @@  TEST_F(child, no_strange_EBADF)
 	EXPECT_EQ(errno, ESRCH);
 }
 
+TEST(pidfd_self)
+{
+	int memfd = sys_memfd_create("test_self", 0);
+	unsigned long page_size = sysconf(_SC_PAGESIZE);
+	int newfd;
+	char *ptr;
+	pthread_t thread;
+	void *res;
+	int err;
+
+	ASSERT_GE(memfd, 0);
+	ASSERT_EQ(ftruncate(memfd, page_size), 0);
+
+	/*
+	 * Map so we can assert that the duplicated fd references the same
+	 * memory.
+	 */
+	ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
+		   MAP_SHARED, memfd, 0);
+	ASSERT_NE(ptr, MAP_FAILED);
+	ptr[0] = 'x';
+	ASSERT_EQ(munmap(ptr, page_size), 0);
+
+	/* Now get a duplicate of our memfd. */
+	newfd = sys_pidfd_getfd(PIDFD_SELF_THREAD_GROUP, memfd, 0);
+	ASSERT_GE(newfd, 0);
+	ASSERT_NE(memfd, newfd);
+
+	/* Now map duplicate fd and make sure it references the same memory. */
+	ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
+		   MAP_SHARED, newfd, 0);
+	ASSERT_NE(ptr, MAP_FAILED);
+	ASSERT_EQ(ptr[0], 'x');
+	ASSERT_EQ(munmap(ptr, page_size), 0);
+
+	/* Cleanup. */
+	close(memfd);
+	close(newfd);
+
+	/*
+	 * Fire up the thread and assert that we can lookup the thread-specific
+	 * PIDFD_SELF_THREAD (also aliased by PIDFD_SELF).
+	 */
+	ASSERT_EQ(pthread_create(&thread, NULL, pidfd_self_thread_worker,
+				 (void *)page_size), 0);
+	ASSERT_EQ(pthread_join(thread, &res), 0);
+	err = (int)(intptr_t)res;
+
+	ASSERT_EQ(err, 0);
+}
+
 #if __NR_pidfd_getfd == -1
 int main(void)
 {
diff --git a/tools/testing/selftests/pidfd/pidfd_setns_test.c b/tools/testing/selftests/pidfd/pidfd_setns_test.c
index 7c2a4349170a..bbd39dc5ceb7 100644
--- a/tools/testing/selftests/pidfd/pidfd_setns_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_setns_test.c
@@ -752,4 +752,15 @@  TEST(setns_einval)
 	close(fd);
 }
 
+TEST(setns_pidfd_self_disallowed)
+{
+	ASSERT_EQ(setns(PIDFD_SELF_THREAD, 0), -1);
+	EXPECT_EQ(errno, EBADF);
+
+	errno = 0;
+
+	ASSERT_EQ(setns(PIDFD_SELF_THREAD_GROUP, 0), -1);
+	EXPECT_EQ(errno, EBADF);
+}
+
 TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/pidfd/pidfd_test.c b/tools/testing/selftests/pidfd/pidfd_test.c
index 9faa686f90e4..440447cf89ba 100644
--- a/tools/testing/selftests/pidfd/pidfd_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_test.c
@@ -42,12 +42,41 @@  static pid_t pidfd_clone(int flags, int *pidfd, int (*fn)(void *))
 #endif
 }
 
-static int signal_received;
+static pthread_t signal_received;
 
 static void set_signal_received_on_sigusr1(int sig)
 {
 	if (sig == SIGUSR1)
-		signal_received = 1;
+		signal_received = pthread_self();
+}
+
+static int send_signal(int pidfd)
+{
+	int ret = 0;
+
+	if (sys_pidfd_send_signal(pidfd, SIGUSR1, NULL, 0) < 0) {
+		ret = -EINVAL;
+		goto exit;
+	}
+
+	if (signal_received != pthread_self()) {
+		ret = -EINVAL;
+		goto exit;
+	}
+
+exit:
+	signal_received = 0;
+	return ret;
+}
+
+static void *send_signal_worker(void *arg)
+{
+	int pidfd = (int)(intptr_t)arg;
+	int ret;
+
+	/* We forward any errors for the caller to handle. */
+	ret = send_signal(pidfd);
+	return (void *)(intptr_t)ret;
 }
 
 /*
@@ -56,8 +85,11 @@  static void set_signal_received_on_sigusr1(int sig)
  */
 static int test_pidfd_send_signal_simple_success(void)
 {
-	int pidfd, ret;
+	int pidfd;
 	const char *test_name = "pidfd_send_signal send SIGUSR1";
+	pthread_t thread;
+	void *thread_res;
+	int err;
 
 	if (!have_pidfd_send_signal) {
 		ksft_test_result_skip(
@@ -66,25 +98,45 @@  static int test_pidfd_send_signal_simple_success(void)
 		return 0;
 	}
 
+	signal(SIGUSR1, set_signal_received_on_sigusr1);
+
+	/* Try sending a signal to ourselves via /proc/self. */
 	pidfd = open("/proc/self", O_DIRECTORY | O_CLOEXEC);
 	if (pidfd < 0)
 		ksft_exit_fail_msg(
 			"%s test: Failed to open process file descriptor\n",
 			test_name);
+	err = send_signal(pidfd);
+	if (err)
+		ksft_exit_fail_msg(
+			"%s test: Error %d on sending pidfd signal\n",
+			test_name, err);
+	close(pidfd);
 
-	signal(SIGUSR1, set_signal_received_on_sigusr1);
+	/* Now try the same thing only using PIDFD_SELF_THREAD_GROUP. */
+	err = send_signal(PIDFD_SELF_THREAD_GROUP);
+	if (err)
+		ksft_exit_fail_msg(
+			"%s test: Error %d on PIDFD_SELF_THREAD_GROUP signal\n",
+			test_name, err);
 
-	ret = sys_pidfd_send_signal(pidfd, SIGUSR1, NULL, 0);
-	close(pidfd);
-	if (ret < 0)
-		ksft_exit_fail_msg("%s test: Failed to send signal\n",
+	/*
+	 * Now try the same thing in a thread and assert thread ID is equal to
+	 * worker thread ID.
+	 */
+	if (pthread_create(&thread, NULL, send_signal_worker,
+			   (void *)(intptr_t)PIDFD_SELF_THREAD))
+		ksft_exit_fail_msg("%s test: Failed to create thread\n",
 				   test_name);
-
-	if (signal_received != 1)
-		ksft_exit_fail_msg("%s test: Failed to receive signal\n",
+	if (pthread_join(thread, &thread_res))
+		ksft_exit_fail_msg("%s test: Failed to join thread\n",
 				   test_name);
+	err = (int)(intptr_t)thread_res;
+	if (err)
+		ksft_exit_fail_msg(
+			"%s test: Error %d on PIDFD_SELF_THREAD signal\n",
+			test_name, err);
 
-	signal_received = 0;
 	ksft_test_result_pass("%s test: Sent signal\n", test_name);
 	return 0;
 }