perf: Make rb_alloc_aux() return an error immediately if nr_pages <= 0

rb_alloc_aux() should not be called with nr_pages <= 0. Make it more robust
and readable by returning an error immediately in that case.

Signed-off-by: Adrian Hunter <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: ahunter6

kernel/events/ring_buffer.c

@@ -682,6 +682,9 @@ int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event,
 	if (!has_aux(event))
 		return -EOPNOTSUPP;
 
+	if (nr_pages <= 0)
+		return -EINVAL;
+
 	if (!overwrite) {
 		/*
 		 * Watermark defaults to half the buffer, and so does the