hrtimer_nanosleep(): Pass rmtp in restart_block

Store the pointer to the timespec which gets updated with the remaining
time in the restart block and remove the function argument.

[ tglx: Added changelog ]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170607084241.28657-3-viro@ZenIV.linux.org.uk

include/linux/hrtimer.h

@@ -453,7 +453,6 @@ static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 
 /* Precise sleep: */
 extern long hrtimer_nanosleep(struct timespec64 *rqtp,
-			      struct timespec __user *rmtp,
 			      const enum hrtimer_mode mode,
 			      const clockid_t clockid);
 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);

kernel/compat.c

@@ -253,9 +253,9 @@ COMPAT_SYSCALL_DEFINE2(nanosleep, struct compat_timespec __user *, rqtp,
 
 	oldfs = get_fs();
 	set_fs(KERNEL_DS);
-	ret = hrtimer_nanosleep(&tu64,
-				rmtp ? (struct timespec __user *)&rmt : NULL,
-				HRTIMER_MODE_REL, CLOCK_MONOTONIC);
+	current->restart_block.nanosleep.rmtp =
+				rmtp ? (struct timespec __user *)&rmt : NULL;
+	ret = hrtimer_nanosleep(&tu64, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
 	set_fs(oldfs);
 
 	/*

kernel/time/hrtimer.c

@@ -1503,10 +1503,11 @@ long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
 	return ret;
 }
 
-long hrtimer_nanosleep(struct timespec64 *rqtp, struct timespec __user *rmtp,
+long hrtimer_nanosleep(struct timespec64 *rqtp,
 		       const enum hrtimer_mode mode, const clockid_t clockid)
 {
-	struct restart_block *restart;
+	struct restart_block *restart = &current->restart_block;
+	struct timespec __user *rmtp;
 	struct hrtimer_sleeper t;
 	int ret = 0;
 	u64 slack;
@@ -1526,16 +1527,15 @@ long hrtimer_nanosleep(struct timespec64 *rqtp, struct timespec __user *rmtp,
 		goto out;
 	}
 
+	rmtp = restart->nanosleep.rmtp;
 	if (rmtp) {
 		ret = update_rmtp(&t.timer, rmtp);
 		if (ret <= 0)
 			goto out;
 	}
 
-	restart = &current->restart_block;
 	restart->fn = hrtimer_nanosleep_restart;
 	restart->nanosleep.clockid = t.timer.base->clockid;
-	restart->nanosleep.rmtp = rmtp;
 	restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
 
 	ret = -ERESTART_RESTARTBLOCK;
@@ -1557,7 +1557,8 @@ SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
 	if (!timespec64_valid(&tu64))
 		return -EINVAL;
 
-	return hrtimer_nanosleep(&tu64, rmtp, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
+	current->restart_block.nanosleep.rmtp = rmtp;
+	return hrtimer_nanosleep(&tu64, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
 }
 
 /*

kernel/time/posix-stubs.c

@@ -115,7 +115,10 @@ SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
 		t64 = timespec_to_timespec64(t);
 		if (!timespec64_valid(&t64))
 			return -EINVAL;
-		return hrtimer_nanosleep(&t64, rmtp, flags & TIMER_ABSTIME ?
+		if (flags & TIMER_ABSTIME)
+			rmtp = NULL;
+		current->restart_block.nanosleep.rmtp = rmtp;
+		return hrtimer_nanosleep(&t64, flags & TIMER_ABSTIME ?
 					 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
 					 which_clock);
 	default:

kernel/time/posix-timers.c

@@ -1043,7 +1043,10 @@ SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
 static int common_nsleep(const clockid_t which_clock, int flags,
 			 struct timespec64 *tsave, struct timespec __user *rmtp)
 {
-	return hrtimer_nanosleep(tsave, rmtp, flags & TIMER_ABSTIME ?
+	if (flags & TIMER_ABSTIME)
+		rmtp = NULL;
+	current->restart_block.nanosleep.rmtp = rmtp;
+	return hrtimer_nanosleep(tsave, flags & TIMER_ABSTIME ?
 				 HRTIMER_MODE_ABS : HRTIMER_MODE_REL,
 				 which_clock);
 }