posix-timers: Add proper state tracking

Right now the state tracking is done by two struct members:

 - it_active:
     A boolean which tracks armed/disarmed state

 - it_signal_seq:
     A sequence counter which is used to invalidate settings
     and prevent rearming

Replace it_active with it_status and keep properly track about the states
in one place.

This allows to reuse it_signal_seq to track reprogramming, disarm and
delete operations in order to drop signals which are related to the state
previous of those operations.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20241001083835.670337048@linutronix.de

1 files changed, 8 insertions, 7 deletions

diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 993243b5be98..12f828d704b1 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -453,7 +453,6 @@ static void disarm_timer(struct k_itimer *timer, struct task_struct *p)
 	struct cpu_timer *ctmr = &timer->it.cpu;
 	struct posix_cputimer_base *base;
 
-	timer->it_active = 0;
 	if (!cpu_timer_dequeue(ctmr))
 		return;
 
@@ -494,11 +493,12 @@ static int posix_cpu_timer_del(struct k_itimer *timer)
 		 */
 		WARN_ON_ONCE(ctmr->head || timerqueue_node_queued(&ctmr->node));
 	} else {
-		if (timer->it.cpu.firing)
+		if (timer->it.cpu.firing) {
 			ret = TIMER_RETRY;
-		else
+		} else {
 			disarm_timer(timer, p);
-
+			timer->it_status = POSIX_TIMER_DISARMED;
+		}
 		unlock_task_sighand(p, &flags);
 	}
 
@@ -560,7 +560,7 @@ static void arm_timer(struct k_itimer *timer, struct task_struct *p)
 	struct cpu_timer *ctmr = &timer->it.cpu;
 	u64 newexp = cpu_timer_getexpires(ctmr);
 
-	timer->it_active = 1;
+	timer->it_status = POSIX_TIMER_ARMED;
 	if (!cpu_timer_enqueue(&base->tqhead, ctmr))
 		return;
 
@@ -586,7 +586,8 @@ static void cpu_timer_fire(struct k_itimer *timer)
 {
 	struct cpu_timer *ctmr = &timer->it.cpu;
 
-	timer->it_active = 0;
+	timer->it_status = POSIX_TIMER_DISARMED;
+
 	if (unlikely(timer->sigq == NULL)) {
 		/*
 		 * This a special case for clock_nanosleep,
@@ -671,7 +672,7 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
 		ret = TIMER_RETRY;
 	} else {
 		cpu_timer_dequeue(ctmr);
-		timer->it_active = 0;
+		timer->it_status = POSIX_TIMER_DISARMED;
 	}
 
 	/*