signal: make wants_signal() return bool

wants_signal() already behaves like a boolean function.  Let's actually
declare it as such too.

Link: http://lkml.kernel.org/r/20180602103653.18181-15-christian@brauner.io
Signed-off-by: Christian Brauner <christian@brauner.io>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: James Morris <james.morris@microsoft.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/signal.c

@@ -879,16 +879,20 @@ static bool prepare_signal(int sig, struct task_struct *p, bool force)
  * as soon as they're available, so putting the signal on the shared queue
  * will be equivalent to sending it to one such thread.
  */
-static inline int wants_signal(int sig, struct task_struct *p)
+static inline bool wants_signal(int sig, struct task_struct *p)
 {
 	if (sigismember(&p->blocked, sig))
-		return 0;
+		return false;
+
 	if (p->flags & PF_EXITING)
-		return 0;
+		return false;
+
 	if (sig == SIGKILL)
-		return 1;
+		return true;
+
 	if (task_is_stopped_or_traced(p))
-		return 0;
+		return false;
+
 	return task_curr(p) || !signal_pending(p);
 }