Changes in pidfd_exec_helper.c

bbfd5594756011167b8f8de9a00e0c946afda1e6 - Merge drm/drm-next into drm-intel-gt-next

Wed, 28 May 2025 09:20:17 +0200

Merge drm/drm-next into drm-intel-gt-nextNeed to pull in a67221b5eb8d ("drm/i915/dp: Return min bpc supported by source instead of 0")in order to fix build breakage on GCC 9.4.0 (from Ubuntu 20.04).Signed-off-by: Joonas Lahtinen List of files: /linux/tools/testing/selftests/pidfd/pidfd_exec_helper.c

db5302ae571beec635c1a96e7f72926a4e65195e - Merge drm/drm-next into drm-intel-next

Fri, 16 May 2025 09:22:36 +0200

Merge drm/drm-next into drm-intel-nextBackmerge to sync with v6.15-rc, xe, and specifically async flip changesin drm-misc.Signed-off-by: Jani Nikula List of files: /linux/tools/testing/selftests/pidfd/pidfd_exec_helper.c

4f9786035f9e519db41375818e1d0b5f20da2f10 - Merge branch 'next' into for-linus

Mon, 02 Jun 2025 06:41:07 +0200

Merge branch 'next' into for-linusPrepare input updates for 6.16 merge window. List of files: /linux/tools/testing/selftests/pidfd/pidfd_exec_helper.c

d51b9d81f7883f526b26e3ab903e646274aebeb1 - Merge tag 'v6.15-rc6' into next

Fri, 16 May 2025 01:20:39 +0200

Merge tag 'v6.15-rc6' into nextSync up with mainline to bring in xpad controller changes. List of files: /linux/tools/testing/selftests/pidfd/pidfd_exec_helper.c

844e31bbaef7c8a6ff2c0fbac45c0c85b5484482 - Merge remote-tracking branch 'drm-misc/drm-misc-next' into msm-next

Tue, 29 Apr 2025 22:42:29 +0200

Merge remote-tracking branch 'drm-misc/drm-misc-next' into msm-nextMerge drm-misc-next to get commit Fixes: fec450ca15af ("drm/display:hdmi: provide central data authority for ACR params").Signed-off-by: Rob Clark List of files: /linux/tools/testing/selftests/pidfd/pidfd_exec_helper.c

3ab7ae8e07f888f223027f0ef84d33e43919ad55 - Merge drm/drm-next into drm-xe-next

Thu, 24 Apr 2025 13:34:55 +0200

Merge drm/drm-next into drm-xe-nextBackmerge to bring in linux 6.15-rc.Signed-off-by: Thomas Hellström List of files: /linux/tools/testing/selftests/pidfd/pidfd_exec_helper.c

1afba39f9305fe4061a4e70baa6ebab9d41459da - Merge drm/drm-next into drm-misc-next

Mon, 07 Apr 2025 13:47:40 +0200

Merge drm/drm-next into drm-misc-nextBackmerging to get v6.15-rc1 into drm-misc-next. Also fixes abuild issue when enabling CONFIG_DRM_SCHED_KUNIT_TEST.Signed-off-by: Thomas Zimmermann List of files: /linux/tools/testing/selftests/pidfd/pidfd_exec_helper.c

1260ed77798502de9c98020040d2995008de10cc - Merge drm/drm-fixes into drm-misc-fixes

Tue, 08 Apr 2025 10:15:47 +0200

Merge drm/drm-fixes into drm-misc-fixesBackmerging to get updates from v6.15-rc1.Signed-off-by: Thomas Zimmermann List of files: /linux/tools/testing/selftests/pidfd/pidfd_exec_helper.c

2487b6b9bf2874cfca7efb59c95650c5b1d88d43 - Merge branch 'linus' into x86/urgent, to pick up fixes and refresh the branch

Tue, 25 Mar 2025 08:17:25 +0100

Merge branch 'linus' into x86/urgent, to pick up fixes and refresh the branchSigned-off-by: Ingo Molnar List of files: /linux/tools/testing/selftests/pidfd/pidfd_exec_helper.c

df00ded23a6b4df888237333b1f86067d24113b2 - Merge tag 'vfs-6.15-rc1.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Mon, 24 Mar 2025 18:16:37 +0100

Merge tag 'vfs-6.15-rc1.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfsPull vfs pidfs updates from Christian Brauner: - Allow retrieving exit information after a process has been reaped through pidfds via the new PIDFD_INTO_EXIT extension for the PIDFD_GET_INFO ioctl. Various tools need access to information about a process/task even after it has already been reaped. Pidfd polling allows waiting on either task exit or for a task to have been reaped. The contract for PIDFD_INFO_EXIT is simply that EPOLLHUP must be observed before exit information can be retrieved, i.e., exit information is only provided once the task has been reaped and then can be retrieved as long as the pidfd is open. - Add PIDFD_SELF_{THREAD,THREAD_GROUP} sentinels allowing userspace to forgo allocating a file descriptor for their own process. This is useful in scenarios where users want to act on their own process through pidfds and is akin to AT_FDCWD. - Improve premature thread-group leader and subthread exec behavior when polling on pidfds: (1) During a multi-threaded exec by a subthread, i.e., non-thread-group leader thread, all other threads in the thread-group including the thread-group leader are killed and the struct pid of the thread-group leader will be taken over by the subthread that called exec. IOW, two tasks change their TIDs. (2) A premature thread-group leader exit means that the thread-group leader exited before all of the other subthreads in the thread-group have exited. Both cases lead to inconsistencies for pidfd polling with PIDFD_THREAD. Any caller that holds a PIDFD_THREAD pidfd to the current thread-group leader may or may not see an exit notification on the file descriptor depending on when poll is performed. If the poll is performed before the exec of the subthread has concluded an exit notification is generated for the old thread-group leader. If the poll is performed after the exec of the subthread has concluded no exit notification is generated for the old thread-group leader. The correct behavior is to simply not generate an exit notification on the struct pid of a subhthread exec because the struct pid is taken over by the subthread and thus remains alive. But this is difficult to handle because a thread-group may exit premature as mentioned in (2). In that case an exit notification is reliably generated but the subthreads may continue to run for an indeterminate amount of time and thus also may exec at some point. After this pull no exit notifications will be generated for a PIDFD_THREAD pidfd for a thread-group leader until all subthreads have been reaped. If a subthread should exec before no exit notification will be generated until that task exits or it creates subthreads and repeates the cycle. This means an exit notification indicates the ability for the father to reap the child.* tag 'vfs-6.15-rc1.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (25 commits) selftests/pidfd: third test for multi-threaded exec polling selftests/pidfd: second test for multi-threaded exec polling selftests/pidfd: first test for multi-threaded exec polling pidfs: improve multi-threaded exec and premature thread-group leader exit polling pidfs: ensure that PIDFS_INFO_EXIT is available selftests/pidfd: add seventh PIDFD_INFO_EXIT selftest selftests/pidfd: add sixth PIDFD_INFO_EXIT selftest selftests/pidfd: add fifth PIDFD_INFO_EXIT selftest selftests/pidfd: add fourth PIDFD_INFO_EXIT selftest selftests/pidfd: add third PIDFD_INFO_EXIT selftest selftests/pidfd: add second PIDFD_INFO_EXIT selftest selftests/pidfd: add first PIDFD_INFO_EXIT selftest selftests/pidfd: expand common pidfd header pidfs/selftests: ensure correct headers for ioctl handling selftests/pidfd: fix header inclusion pidfs: allow to retrieve exit information pidfs: record exit code and cgroupid at exit pidfs: use private inode slab cache pidfs: move setting flags into pidfs_alloc_file() pidfd: rely on automatic cleanup in __pidfd_prepare() ... List of files: /linux/tools/testing/selftests/pidfd/pidfd_exec_helper.c

6092c50160056dfa0f747df5e8b107124146e363 - Merge patch series "pidfs: provide information after task has been reaped"

Wed, 05 Mar 2025 13:07:51 +0100

Merge patch series "pidfs: provide information after task has been reaped"Christian Brauner says:Various tools need access to information about a process/task even afterit has already been reaped. For example, systemd's journal logs and usessuch information as the cgroup id and exit status to deal with processesthat have been sent via SCM_PIDFD or SCM_PEERPIDFD. By the time thepidfd is received the process might have already been reaped.This series aims to provide information by extending the PIDFD_GET_INFOioctl to retrieve the exit code and cgroup id. There might be otherstuff that we would want in the future.Pidfd polling allows waiting on either task exit or for a task to havebeen reaped. The contract for PIDFD_INFO_EXIT is simply that EPOLLHUPmust be observed before exit information can be retrieved, i.e., exitinformation is only provided once the task has been reaped.Note, that if a thread-group leader exits before other threads in thethread-group then exit information will only be available once thethread-group is empty. This aligns with wait() as well, where reaping ofa thread-group leader that exited before the thread-group was empty isdelayed until the thread-group is empty.With PIDFD_INFO_EXIT autoreaping might actually become usable because itmeans a parent can ignore SIGCHLD or set SA_NOCLDWAIT and simply usepidfd polling and PIDFD_INFO_EXIT to get get status information for itschildren. The kernel will autocleanup right away instead of delaying.This includes expansive selftests including for thread-group behior andmulti-threaded exec by a non-thread-group leader thread.* patches from https://lore.kernel.org/r/20250305-work-pidfs-kill_on_last_close-v3-0-c8c3d8361705@kernel.org: selftests/pidfd: add seventh PIDFD_INFO_EXIT selftest selftests/pidfd: add sixth PIDFD_INFO_EXIT selftest selftests/pidfd: add fifth PIDFD_INFO_EXIT selftest selftests/pidfd: add fourth PIDFD_INFO_EXIT selftest selftests/pidfd: add third PIDFD_INFO_EXIT selftest selftests/pidfd: add second PIDFD_INFO_EXIT selftest selftests/pidfd: add first PIDFD_INFO_EXIT selftest selftests/pidfd: expand common pidfd header pidfs/selftests: ensure correct headers for ioctl handling selftests/pidfd: fix header inclusion pidfs: allow to retrieve exit information pidfs: record exit code and cgroupid at exit pidfs: use private inode slab cache pidfs: move setting flags into pidfs_alloc_file() pidfd: rely on automatic cleanup in __pidfd_prepare() pidfs: switch to copy_struct_to_user()Link: https://lore.kernel.org/r/20250305-work-pidfs-kill_on_last_close-v3-0-c8c3d8361705@kernel.orgSigned-off-by: Christian Brauner List of files: /linux/tools/testing/selftests/pidfd/pidfd_exec_helper.c

56f235da15d02c550c0ae25da9c62ecfe7222d38 - selftests/pidfd: add seventh PIDFD_INFO_EXIT selftest

Wed, 05 Mar 2025 11:08:26 +0100

selftests/pidfd: add seventh PIDFD_INFO_EXIT selftestAdd a selftest for PIDFD_INFO_EXIT behavior.Link: https://lore.kernel.org/r/20250305-work-pidfs-kill_on_last_close-v3-16-c8c3d8361705@kernel.orgSigned-off-by: Christian Brauner List of files: /linux/tools/testing/selftests/pidfd/pidfd_exec_helper.c