[patch v4 21/27] signal: Provide ignored_posix_timers list

[Thomas Gleixner <tglx@linutronix.de>]

From: Thomas Gleixner <tglx@linutronix.de>

To prepare for handling posix timer signals on sigaction(SIG_IGN) properly,
add a list to task::signal.

This list will be used to queue posix timers so their signal can be
requeued when SIG_IGN is lifted later.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

---
 include/linux/sched/signal.h | 1 +
 init/init_task.c             | 5 +++--
 kernel/fork.c                | 1 +
 3 files changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 02972fd41931..d5d03d919df8 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -138,6 +138,7 @@ struct signal_struct {
 	/* POSIX.1b Interval Timers */
 	unsigned int		next_posix_timer_id;
 	struct hlist_head	posix_timers;
+	struct hlist_head	ignored_posix_timers;
 
 	/* ITIMER_REAL timer for the process */
 	struct hrtimer real_timer;
diff --git a/init/init_task.c b/init/init_task.c
index 5d0399bc8d2f..65af2ba93f25 100644
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -29,8 +29,9 @@ static struct signal_struct init_signals = {
 	.cred_guard_mutex = __MUTEX_INITIALIZER(init_signals.cred_guard_mutex),
 	.exec_update_lock = __RWSEM_INITIALIZER(init_signals.exec_update_lock),
 #ifdef CONFIG_POSIX_TIMERS
-	.posix_timers	= HLIST_HEAD_INIT,
-	.cputimer	= {
+	.posix_timers		= HLIST_HEAD_INIT,
+	.ignored_posix_timers	= HLIST_HEAD_INIT,
+	.cputimer		= {
 		.cputime_atomic	= INIT_CPUTIME_ATOMIC,
 	},
 #endif
diff --git a/kernel/fork.c b/kernel/fork.c
index c1b343cba560..bef4b51bd474 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1862,6 +1862,7 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
 
 #ifdef CONFIG_POSIX_TIMERS
 	INIT_HLIST_HEAD(&sig->posix_timers);
+	INIT_HLIST_HEAD(&sig->ignored_posix_timers);
 	hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	sig->real_timer.function = it_real_fn;
 #endif