signal: sys_rt_sigtimedwait: simplify the timeout logic

No functional changes, cleanup compat_sys_rt_sigtimedwait() and
sys_rt_sigtimedwait().

Calculate the timeout before we take ->siglock, this simplifies and
lessens the code. Use timespec_valid() to check the timespec.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Matt Fleming <matt.fleming@linux.intel.com>

kernel/compat.c

@@ -893,7 +893,7 @@ compat_sys_rt_sigtimedwait (compat_sigset_t __user *uthese,
 	int sig;
 	struct timespec t;
 	siginfo_t info;
-	long ret, timeout = 0;
+	long ret, timeout;
 
 	if (sigsetsize != sizeof(sigset_t))
 		return -EINVAL;
@@ -904,36 +904,30 @@ compat_sys_rt_sigtimedwait (compat_sigset_t __user *uthese,
 	sigdelsetmask(&s,sigmask(SIGKILL)|sigmask(SIGSTOP));
 	signotset(&s);
 
+	timeout = MAX_SCHEDULE_TIMEOUT;
 	if (uts) {
 		if (get_compat_timespec (&t, uts))
 			return -EFAULT;
-		if (t.tv_nsec >= 1000000000L || t.tv_nsec < 0
-				|| t.tv_sec < 0)
+		if (!timespec_valid(&t))
 			return -EINVAL;
+		timeout = timespec_to_jiffies(&t) + (t.tv_sec || t.tv_nsec);
 	}
 
 	spin_lock_irq(&current->sighand->siglock);
 	sig = dequeue_signal(current, &s, &info);
-	if (!sig) {
-		timeout = MAX_SCHEDULE_TIMEOUT;
-		if (uts)
-			timeout = timespec_to_jiffies(&t)
-				+(t.tv_sec || t.tv_nsec);
-		if (timeout) {
-			current->real_blocked = current->blocked;
-			sigandsets(&current->blocked, &current->blocked, &s);
-
-			recalc_sigpending();
-			spin_unlock_irq(&current->sighand->siglock);
-
-			timeout = schedule_timeout_interruptible(timeout);
-
-			spin_lock_irq(&current->sighand->siglock);
-			sig = dequeue_signal(current, &s, &info);
-			current->blocked = current->real_blocked;
-			siginitset(&current->real_blocked, 0);
-			recalc_sigpending();
-		}
+	if (!sig && timeout) {
+		current->real_blocked = current->blocked;
+		sigandsets(&current->blocked, &current->blocked, &s);
+		recalc_sigpending();
+		spin_unlock_irq(&current->sighand->siglock);
+
+		timeout = schedule_timeout_interruptible(timeout);
+
+		spin_lock_irq(&current->sighand->siglock);
+		sig = dequeue_signal(current, &s, &info);
+		current->blocked = current->real_blocked;
+		siginitset(&current->real_blocked, 0);
+		recalc_sigpending();
 	}
 	spin_unlock_irq(&current->sighand->siglock);
 
@@ -943,7 +937,7 @@ compat_sys_rt_sigtimedwait (compat_sigset_t __user *uthese,
 			if (copy_siginfo_to_user32(uinfo, &info))
 				ret = -EFAULT;
 		}
-	}else {
+	} else {
 		ret = timeout?-EINTR:-EAGAIN;
 	}
 	return ret;

kernel/signal.c

@@ -2519,7 +2519,7 @@ SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
 	sigset_t these;
 	struct timespec ts;
 	siginfo_t info;
-	long timeout = 0;
+	long timeout;
 
 	/* XXX: Don't preclude handling different sized sigset_t's.  */
 	if (sigsetsize != sizeof(sigset_t))
@@ -2535,41 +2535,35 @@ SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
 	sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
 	signotset(&these);
 
+	timeout = MAX_SCHEDULE_TIMEOUT;
 	if (uts) {
 		if (copy_from_user(&ts, uts, sizeof(ts)))
 			return -EFAULT;
-		if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
-		    || ts.tv_sec < 0)
+		if (!timespec_valid(&ts))
 			return -EINVAL;
+		timeout = timespec_to_jiffies(&ts) + (ts.tv_sec || ts.tv_nsec);
 	}
 
 	spin_lock_irq(&current->sighand->siglock);
 	sig = dequeue_signal(current, &these, &info);
-	if (!sig) {
-		timeout = MAX_SCHEDULE_TIMEOUT;
-		if (uts)
-			timeout = (timespec_to_jiffies(&ts)
-				   + (ts.tv_sec || ts.tv_nsec));
+	if (!sig && timeout) {
+		/*
+		 * None ready -- temporarily unblock those we're
+		 * interested while we are sleeping in so that we'll
+		 * be awakened when they arrive.
+		 */
+		current->real_blocked = current->blocked;
+		sigandsets(&current->blocked, &current->blocked, &these);
+		recalc_sigpending();
+		spin_unlock_irq(&current->sighand->siglock);
 
-		if (timeout) {
-			/*
-			 * None ready -- temporarily unblock those we're
-			 * interested while we are sleeping in so that we'll
-			 * be awakened when they arrive.
-			 */
-			current->real_blocked = current->blocked;
-			sigandsets(&current->blocked, &current->blocked, &these);
-			recalc_sigpending();
-			spin_unlock_irq(&current->sighand->siglock);
-
-			timeout = schedule_timeout_interruptible(timeout);
-
-			spin_lock_irq(&current->sighand->siglock);
-			sig = dequeue_signal(current, &these, &info);
-			current->blocked = current->real_blocked;
-			siginitset(&current->real_blocked, 0);
-			recalc_sigpending();
-		}
+		timeout = schedule_timeout_interruptible(timeout);
+
+		spin_lock_irq(&current->sighand->siglock);
+		sig = dequeue_signal(current, &these, &info);
+		current->blocked = current->real_blocked;
+		siginitset(&current->real_blocked, 0);
+		recalc_sigpending();
 	}
 	spin_unlock_irq(&current->sighand->siglock);