The patch titled
signals: send_signal: factor out SIGNAL_GROUP_EXIT checks
has been added to the -mm tree. Its filename is
signals-send_signal-factor-out-signal_group_exit-checks.patch
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*** 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
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The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: signals: send_signal: factor out SIGNAL_GROUP_EXIT checks
From: Oleg Nesterov <oleg@xxxxxxxxxx>
The signal has no effect (but can provoke the unnecessary wakeup) if the
thread group is dying. Let's make this explicit and check SIGNAL_GROUP_EXIT
only once in handle_stop_signal() renamed to prepare_signal().
>From now the actual signal-delivery path doesn't need to take the special
SIGNAL_GROUP_EXIT case into account.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/signal.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff -puN kernel/signal.c~signals-send_signal-factor-out-signal_group_exit-checks kernel/signal.c
--- a/kernel/signal.c~signals-send_signal-factor-out-signal_group_exit-checks
+++ a/kernel/signal.c
@@ -564,16 +564,16 @@ static void do_notify_parent_cldstop(str
* actual continuing for SIGCONT, but not the actual stopping for stop
* signals. The process stop is done as a signal action for SIG_DFL.
*/
-static void handle_stop_signal(int sig, struct task_struct *p)
+static int prepare_signal(int sig, struct task_struct *p)
{
struct signal_struct *signal = p->signal;
struct task_struct *t;
- if (signal->flags & SIGNAL_GROUP_EXIT)
+ if (unlikely(signal->flags & SIGNAL_GROUP_EXIT))
/*
* The process is in the middle of dying already.
*/
- return;
+ return 0;
if (sig_kernel_stop(sig)) {
/*
@@ -644,6 +644,8 @@ static void handle_stop_signal(int sig,
signal->flags &= ~SIGNAL_STOP_DEQUEUED;
}
}
+
+ return 1;
}
/*
@@ -708,8 +710,7 @@ static void complete_signal(int sig, str
* Found a killable thread. If the signal will be fatal,
* then start taking the whole group down immediately.
*/
- if (sig_fatal(p, sig) && !(signal->flags & SIGNAL_GROUP_EXIT) &&
- !sigismember(&t->real_blocked, sig) &&
+ if (sig_fatal(p, sig) && !sigismember(&t->real_blocked, sig) &&
(sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
/*
* This signal will be fatal to the whole group.
@@ -753,7 +754,8 @@ static int send_signal(int sig, struct s
struct sigqueue *q;
assert_spin_locked(&t->sighand->siglock);
- handle_stop_signal(sig, t);
+ if (!likely(prepare_signal(sig, t)))
+ return 0;
pending = group ? &t->signal->shared_pending : &t->pending;
/*
@@ -1247,9 +1249,10 @@ int send_sigqueue(struct sigqueue *q, st
if (!likely(lock_task_sighand(t, &flags)))
goto ret;
- handle_stop_signal(sig, t);
-
ret = 1;
+ if (!likely(prepare_signal(sig, t)))
+ goto out;
+
if (sig_ignored(t, sig))
goto out;
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
git-hrt.patch
kthread-call-wake_up_process-without-the-lock-being-held.patch
mmap_region-cleanup-the-final-vma_merge-related-code.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-send_signal-factor-out-signal_group_exit-checks.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
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
put_pid-make-sure-we-dont-free-the-live-pid.patch
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