The patch titled
kill_pid_info: don't take now unneeded tasklist_lock
has been added to the -mm tree. Its filename is
kill_pid_info-dont-take-now-unneeded-tasklist_lock.patch
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The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: kill_pid_info: don't take now unneeded tasklist_lock
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Previously handle_stop_signal(SIGCONT) could drop ->siglock. That is why
kill_pid_info(SIGCONT) takes tasklist_lock to make sure the target task can't
go away after unlock. Not needed now.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: Jiri Kosina <jkosina@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/signal.h | 2 --
kernel/signal.c | 7 +------
2 files changed, 1 insertion(+), 8 deletions(-)
diff -puN include/linux/signal.h~kill_pid_info-dont-take-now-unneeded-tasklist_lock include/linux/signal.h
--- a/include/linux/signal.h~kill_pid_info-dont-take-now-unneeded-tasklist_lock
+++ a/include/linux/signal.h
@@ -362,8 +362,6 @@ int unhandled_signal(struct task_struct
#define sig_kernel_stop(sig) \
(((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_STOP_MASK))
-#define sig_needs_tasklist(sig) ((sig) == SIGCONT)
-
#define sig_user_defined(t, signr) \
(((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))
diff -puN kernel/signal.c~kill_pid_info-dont-take-now-unneeded-tasklist_lock kernel/signal.c
--- a/kernel/signal.c~kill_pid_info-dont-take-now-unneeded-tasklist_lock
+++ a/kernel/signal.c
@@ -1039,9 +1039,6 @@ int kill_pid_info(int sig, struct siginf
struct task_struct *p;
rcu_read_lock();
- if (unlikely(sig_needs_tasklist(sig)))
- read_lock(&tasklist_lock);
-
retry:
p = pid_task(pid, PIDTYPE_PID);
if (p) {
@@ -1055,10 +1052,8 @@ retry:
*/
goto retry;
}
-
- if (unlikely(sig_needs_tasklist(sig)))
- read_unlock(&tasklist_lock);
rcu_read_unlock();
+
return error;
}
_
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
ptrace-introduce-task_detached-helper.patch
ptrace-introduce-ptrace_reparented-helper.patch
reparent_thread-use-same_thread_group.patch
document-de_thread-with-exit_notify-connection.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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