signal: make sig_ignored() return bool

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

Link: http://lkml.kernel.org/r/20180602103653.18181-10-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

@@ -85,7 +85,7 @@ static bool sig_task_ignored(struct task_struct *t, int sig, bool force)
 	return sig_handler_ignored(handler, sig);
 }
 
-static int sig_ignored(struct task_struct *t, int sig, bool force)
+static bool sig_ignored(struct task_struct *t, int sig, bool force)
 {
 	/*
 	 * Blocked signals are never ignored, since the
@@ -93,7 +93,7 @@ static int sig_ignored(struct task_struct *t, int sig, bool force)
 	 * unblocked.
 	 */
 	if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
-		return 0;
+		return false;
 
 	/*
 	 * Tracers may want to know about even ignored signal unless it
@@ -101,7 +101,7 @@ static int sig_ignored(struct task_struct *t, int sig, bool force)
 	 * by SIGNAL_UNKILLABLE task.
 	 */
 	if (t->ptrace && sig != SIGKILL)
-		return 0;
+		return false;
 
 	return sig_task_ignored(t, sig, force);
 }