POSIX CPU timer nanosleep creates a k_itimer on stack and uses the sigq
pointer to detect the nanosleep case in the expiry function.

Prepare for embedding sigqueue into struct k_itimer by using a dedicated
flag for nanosleep.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 include/linux/posix-timers.h   |    4 +++-
 kernel/time/posix-cpu-timers.c |    3 ++-
 2 files changed, 5 insertions(+), 2 deletions(-)

--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -42,6 +42,7 @@ static inline int clockid_to_fd(const cl
  * @pid:	Pointer to target task PID
  * @elist:	List head for the expiry list
  * @firing:	Timer is currently firing
+ * @nanosleep:	Timer is used for nanosleep and is not a regular posix-timer
  * @handling:	Pointer to the task which handles expiry
  */
 struct cpu_timer {
@@ -49,7 +50,8 @@ struct cpu_timer {
 	struct timerqueue_head		*head;
 	struct pid			*pid;
 	struct list_head		elist;
-	int				firing;
+	bool				firing;
+	bool				nanosleep;
 	struct task_struct __rcu	*handling;
 };
 
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -588,7 +588,7 @@ static void cpu_timer_fire(struct k_itim
 
 	timer->it_status = POSIX_TIMER_DISARMED;
 
-	if (unlikely(timer->sigq == NULL)) {
+	if (unlikely(ctmr->nanosleep)) {
 		/*
 		 * This a special case for clock_nanosleep,
 		 * not a normal timer from sys_timer_create.
@@ -1479,6 +1479,7 @@ static int do_cpu_nanosleep(const clocki
 	timer.it_overrun = -1;
 	error = posix_cpu_timer_create(&timer);
 	timer.it_process = current;
+	timer.it.cpu.nanosleep = true;
 
 	if (!error) {
 		static struct itimerspec64 zero_it;