futex: Store time as ktime_t in restart block

The futex core uses ktime_t to represent times, use that also for the
restart block.

This allows the simplification of the accessors.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20251110-restart-block-expiration-v1-2-5d39cc93df4f@linutronix.de

Author: t-8ch

include/linux/restart_block.h

@@ -32,7 +32,7 @@ struct restart_block {
 			u32 val;
 			u32 flags;
 			u32 bitset;
-			u64 time;
+			ktime_t time;
 			u32 __user *uaddr2;
 		} futex;
 		/* For nanosleep */

kernel/futex/waitwake.c

@@ -738,12 +738,11 @@ int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time
 static long futex_wait_restart(struct restart_block *restart)
 {
 	u32 __user *uaddr = restart->futex.uaddr;
-	ktime_t t, *tp = NULL;
+	ktime_t *tp = NULL;
+
+	if (restart->futex.flags & FLAGS_HAS_TIMEOUT)
+		tp = &restart->futex.time;
 
-	if (restart->futex.flags & FLAGS_HAS_TIMEOUT) {
-		t = restart->futex.time;
-		tp = &t;
-	}
 	restart->fn = do_no_restart_syscall;
 
 	return (long)futex_wait(uaddr, restart->futex.flags,