kernel/pipe: fix poll support

Two issues:

- is_condition_met() was missing proper code for The
  K_POLL_TYPE_PIPE_DATA_AVAILABLE case

- z_handle_obj_poll_events() was misplaced in z_impl_k_pipe_write()

Note: I added support for the deprecated pipe implementation to
      is_condition_met() but that is untested.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>

kernel/pipe.c

@@ -186,11 +186,12 @@ int z_impl_k_pipe_write(struct k_pipe *pipe, const uint8_t *data, size_t len, k_
 					break;
 				}
 			}
+		}
+
 #ifdef CONFIG_POLL
-			z_handle_obj_poll_events(&pipe->poll_events,
-						 K_POLL_STATE_PIPE_DATA_AVAILABLE);
+		need_resched |= z_handle_obj_poll_events(&pipe->poll_events,
+							 K_POLL_STATE_PIPE_DATA_AVAILABLE);
 #endif /* CONFIG_POLL */
-		}
 
 		written += ring_buf_put(&pipe->buf, &data[written], len - written);
 		if (likely(written == len)) {

kernel/poll.c

@@ -88,8 +88,15 @@ static inline bool is_condition_met(struct k_poll_event *event, uint32_t *state)
 		}
 		break;
 	case K_POLL_TYPE_PIPE_DATA_AVAILABLE:
-		*state = K_POLL_STATE_PIPE_DATA_AVAILABLE;
-		return true;
+#ifdef CONFIG_PIPES
+		if (event->pipe->bytes_used != 0) {
+#else
+		if (!ring_buf_is_empty(&event->pipe->buf)) {
+#endif
+			*state = K_POLL_STATE_PIPE_DATA_AVAILABLE;
+			return true;
+		}
+		break;
 	case K_POLL_TYPE_IGNORE:
 		break;
 	default: