The patch titled signals: de_thread: simplify the ->child_reaper switching has been added to the -mm tree. Its filename is signals-de_thread-simplify-the-child_reaper-switching.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: signals: de_thread: simplify the ->child_reaper switching From: Oleg Nesterov <oleg@xxxxxxxxxx> Now that we rely on SIGNAL_UNKILLABLE flag, de_thread() doesn't need the nasty hack to kill the old ->child_reaper during the mt-exec. This also means we can avoid taking tasklist_lock around zap_other_threads(). Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Roland McGrath <roland@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/exec.c | 15 ++------------- 1 file changed, 2 insertions(+), 13 deletions(-) diff -puN fs/exec.c~signals-de_thread-simplify-the-child_reaper-switching fs/exec.c --- a/fs/exec.c~signals-de_thread-simplify-the-child_reaper-switching +++ a/fs/exec.c @@ -765,9 +765,7 @@ static int de_thread(struct task_struct /* * Kill all other threads in the thread group. - * We must hold tasklist_lock to call zap_other_threads. */ - read_lock(&tasklist_lock); spin_lock_irq(lock); if (signal_group_exit(sig)) { /* @@ -775,21 +773,10 @@ static int de_thread(struct task_struct * return so that the signal is processed. */ spin_unlock_irq(lock); - read_unlock(&tasklist_lock); return -EAGAIN; } - - /* - * child_reaper ignores SIGKILL, change it now. - * Reparenting needs write_lock on tasklist_lock, - * so it is safe to do it under read_lock. - */ - if (unlikely(tsk->group_leader == task_child_reaper(tsk))) - task_active_pid_ns(tsk)->child_reaper = tsk; - sig->group_exit_task = tsk; zap_other_threads(tsk); - read_unlock(&tasklist_lock); /* Account for the thread group leader hanging around: */ count = thread_group_leader(tsk) ? 1 : 2; @@ -820,6 +807,8 @@ static int de_thread(struct task_struct schedule(); } + if (unlikely(task_child_reaper(tsk) == leader)) + task_active_pid_ns(tsk)->child_reaper = tsk; /* * The only record we have of the real-time age of a * process, regardless of execs it's done, is start_time. _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are origin.patch bsd_acct-plain-current-real_parent-access-is-not-always-safe.patch bsd_acct-using-task_struct-tgid-is-not-right-in-pid-namespaces.patch x86-handle_vm86_trap-cleanup.patch git-hrt.patch mmap_region-cleanup-the-final-vma_merge-related-code.patch kthread-call-wake_up_process-without-the-lock-being-held.patch remove-unused-variable-from-send_signal.patch turn-legacy_queue-macro-into-static-inline-function.patch consolidate-checking-for-ignored-legacy-signals.patch consolidate-checking-for-ignored-legacy-signals-simplify.patch signals-do_signal_stop-use-signal_group_exit.patch signals-do_group_exit-use-signal_group_exit-more-consistently.patch lock_task_sighand-add-rcu-lock-unlock.patch k_getrusage-dont-take-rcu_read_lock.patch do_task_stat-dont-take-rcu_read_lock.patch signals-consolidate-checks-for-whether-or-not-to-ignore-a-signal.patch signals-clean-dequeue_signal-from-excess-checks-and-assignments.patch signals-consolidate-send_sigqueue-and-send_group_sigqueue.patch signals-cleanup-security_task_kill-usage-implementation.patch signals-re-assign-cld_continued-notification-from-the-sender-to-reciever.patch kill_pid_info-dont-take-now-unneeded-tasklist_lock.patch handle_stop_signal-unify-partial-full-stop-handling.patch handle_stop_signal-use-the-cached-p-signal-value.patch get_signal_to_deliver-use-the-cached-signal-sighand-values.patch signals-send_sigqueue-dont-take-rcu-lock.patch signals-send_sigqueue-dont-forget-about-handle_stop_signal.patch signals-__group_complete_signal-cache-the-value-of-p-signal.patch signals-send_group_sigqueue-dont-take-tasklist_lock.patch signals-move-handle_stop_signal-into-send_signal.patch signals-do_tkill-dont-use-tasklist_lock.patch signals-do_tkill-dont-use-tasklist_lock-comment.patch signals-send_sig_info-dont-take-tasklist_lock.patch signals-microoptimize-the-usage-of-curr_target.patch signals-move-the-definition-of-__group_complete_signal-up.patch signals-change-send_signal-do_send_sigqueue-to-take-boolean-group-parameter.patch signals-use-__group_complete_signal-for-the-specific-signals-too.patch signals-fold-complete_signal-into-send_signal-do_send_sigqueue.patch signals-unify-send_sigqueue-send_group_sigqueue-completely.patch signals-join-send_sigqueue-with-send_group_sigqueue.patch signals-handle_stop_signal-dont-worry-about-sigkill.patch signals-cleanup-the-usage-of-print_fatal_signal.patch signals-fold-sig_ignored-into-handle_stop_signal.patch signals-fold-sig_ignored-into-handle_stop_signal-comment.patch signals-document-cld_continued-notification-mechanics.patch signals-document-cld_continued-notification-mechanics-more.patch signals-send_signal-be-paranoid-about-signalfd_notify.patch signals-check_kill_permission-check-session-under-tasklist_lock.patch signals-check_kill_permission-remove-tasklist_lock.patch signals-fix-sbin-init-protection-from-unwanted-signals.patch signals-de_thread-simplify-the-child_reaper-switching.patch signals-allow-the-kernel-to-actually-kill-sbin-init.patch ptrace-introduce-task_detached-helper.patch reparent_thread-use-same_thread_group.patch document-de_thread-with-exit_notify-connection.patch ptrace-introduce-ptrace_reparented-helper.patch ptrace-__ptrace_unlink-use-the-ptrace_reparented-helper.patch ptrace-ptrace_attach-use-send_sig_info-instead-force_sig_specific.patch workqueues-shrink-cpu_populated_map-when-cpu-dies.patch workqueues-shrink-cpu_populated_map-when-cpu-dies-fix.patch cleanup_workqueue_thread-remove-the-unneeded-cpu-parameter.patch simplify-cpu_hotplug_begin-put_online_cpus.patch redo-locking-of-tty-pgrp.patch resume-tty-on-susp-and-fix-crnl-order-in-n_tty-line-discipline.patch tty_io-fix-remaining-pid-struct-locking.patch tty_io-fix-remaining-pid-struct-locking-small-cleanup.patch procfs-task-exe-symlink.patch procfs-task-exe-symlink-fix.patch procfs-task-exe-symlink-fix-2.patch free_pidmap-turn-it-into-free_pidmapstruct-upid.patch pids-de_thread-dont-clear-session-pgrp-pids-for-the-old-leader.patch pids-introduce-change_pid-helper.patch pids-sys_setpgid-use-change_pid-helper.patch pids-__set_special_pids-use-change_pid-helper.patch put_pid-make-sure-we-dont-free-the-live-pid.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html