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-rw-r--r--include/linux/init_task.h2
-rw-r--r--include/linux/sched.h12
-rw-r--r--kernel/exit.c1
-rw-r--r--kernel/fork.c7
4 files changed, 22 insertions, 0 deletions
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index f0e52383a001..1516a8ff8f92 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -41,6 +41,7 @@ extern struct fs_struct init_fs;
#define INIT_SIGNALS(sig) { \
.nr_threads = 1, \
+ .thread_head = LIST_HEAD_INIT(init_task.thread_node), \
.wait_chldexit = __WAIT_QUEUE_HEAD_INITIALIZER(sig.wait_chldexit),\
.shared_pending = { \
.list = LIST_HEAD_INIT(sig.shared_pending.list), \
@@ -222,6 +223,7 @@ extern struct task_group root_task_group;
[PIDTYPE_SID] = INIT_PID_LINK(PIDTYPE_SID), \
}, \
.thread_group = LIST_HEAD_INIT(tsk.thread_group), \
+ .thread_node = LIST_HEAD_INIT(init_signals.thread_head), \
INIT_IDS \
INIT_PERF_EVENTS(tsk) \
INIT_TRACE_IRQFLAGS \
diff --git a/include/linux/sched.h b/include/linux/sched.h
index ffccdad050b5..485234d2fd42 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -549,6 +549,7 @@ struct signal_struct {
atomic_t sigcnt;
atomic_t live;
int nr_threads;
+ struct list_head thread_head;
wait_queue_head_t wait_chldexit; /* for wait4() */
@@ -1271,6 +1272,7 @@ struct task_struct {
/* PID/PID hash table linkage. */
struct pid_link pids[PIDTYPE_MAX];
struct list_head thread_group;
+ struct list_head thread_node;
struct completion *vfork_done; /* for vfork() */
int __user *set_child_tid; /* CLONE_CHILD_SETTID */
@@ -2341,6 +2343,16 @@ extern bool current_is_single_threaded(void);
#define while_each_thread(g, t) \
while ((t = next_thread(t)) != g)
+#define __for_each_thread(signal, t) \
+ list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node)
+
+#define for_each_thread(p, t) \
+ __for_each_thread((p)->signal, t)
+
+/* Careful: this is a double loop, 'break' won't work as expected. */
+#define for_each_process_thread(p, t) \
+ for_each_process(p) for_each_thread(p, t)
+
static inline int get_nr_threads(struct task_struct *tsk)
{
return tsk->signal->nr_threads;
diff --git a/kernel/exit.c b/kernel/exit.c
index a949819055d5..1e77fc645317 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -74,6 +74,7 @@ static void __unhash_process(struct task_struct *p, bool group_dead)
__this_cpu_dec(process_counts);
}
list_del_rcu(&p->thread_group);
+ list_del_rcu(&p->thread_node);
}
/*
diff --git a/kernel/fork.c b/kernel/fork.c
index 294189fc7ac8..2f11bbe376b0 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1035,6 +1035,11 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
sig->nr_threads = 1;
atomic_set(&sig->live, 1);
atomic_set(&sig->sigcnt, 1);
+
+ /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
+ sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
+ tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
+
init_waitqueue_head(&sig->wait_chldexit);
sig->curr_target = tsk;
init_sigpending(&sig->shared_pending);
@@ -1474,6 +1479,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
atomic_inc(&current->signal->sigcnt);
list_add_tail_rcu(&p->thread_group,
&p->group_leader->thread_group);
+ list_add_tail_rcu(&p->thread_node,
+ &p->signal->thread_head);
}
attach_pid(p, PIDTYPE_PID);
nr_threads++;