Static error value checking

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fio.c b/fio.c
index 1c2748e..95e06dd 100644
--- a/fio.c
+++ b/fio.c
@@ -149,7 +149,9 @@
 	/*
 	 * get immediately available events, if any
 	 */
-	io_u_queued_complete(td, 0, NULL);
+	r = io_u_queued_complete(td, 0, NULL);
+	if (r < 0)
+		return;
 
 	/*
 	 * now cancel remaining active events
@@ -165,7 +167,7 @@
 	}
 
 	if (td->cur_depth)
-		io_u_queued_complete(td, td->cur_depth, NULL);
+		r = io_u_queued_complete(td, td->cur_depth, NULL);
 }
 
 /*
@@ -203,7 +205,8 @@
 			return 1;
 		}
 
-		io_u_sync_complete(td, io_u, NULL);
+		if (io_u_sync_complete(td, io_u, NULL) < 0)
+			return 1;
 	} else if (ret == FIO_Q_BUSY) {
 		if (td_io_commit(td))
 			return 1;
@@ -228,10 +231,15 @@
 	 * read from disk.
 	 */
 	for_each_file(td, f, i) {
-		fio_io_sync(td, f);
-		file_invalidate_cache(td, f);
+		if (fio_io_sync(td, f))
+			break;
+		if (file_invalidate_cache(td, f))
+			break;
 	}
 
+	if (td->error)
+		return;
+
 	td_set_runstate(td, TD_VERIFYING);
 
 	io_u = NULL;
diff --git a/fio.h b/fio.h
index 282ccf0..e693161 100644
--- a/fio.h
+++ b/fio.h
@@ -566,9 +566,9 @@
  * File setup/shutdown
  */
 extern void close_files(struct thread_data *);
-extern int setup_files(struct thread_data *);
-extern int open_files(struct thread_data *);
-extern int file_invalidate_cache(struct thread_data *, struct fio_file *);
+extern int __must_check setup_files(struct thread_data *);
+extern int __must_check open_files(struct thread_data *);
+extern int __must_check file_invalidate_cache(struct thread_data *, struct fio_file *);
 
 /*
  * ETA/status stuff
@@ -597,15 +597,15 @@
  * Verify helpers
  */
 extern void populate_verify_io_u(struct thread_data *, struct io_u *);
-extern int get_next_verify(struct thread_data *td, struct io_u *);
-extern int verify_io_u(struct io_u *);
+extern int __must_check get_next_verify(struct thread_data *td, struct io_u *);
+extern int __must_check verify_io_u(struct io_u *);
 
 /*
  * Memory helpers
  */
-extern int fio_pin_memory(void);
+extern int __must_check fio_pin_memory(void);
 extern void fio_unpin_memory(void);
-extern int allocate_io_mem(struct thread_data *);
+extern int __must_check allocate_io_mem(struct thread_data *);
 extern void free_io_mem(struct thread_data *);
 
 /*
@@ -616,19 +616,19 @@
 extern struct io_u *get_io_u(struct thread_data *);
 extern void put_io_u(struct thread_data *, struct io_u *);
 extern void requeue_io_u(struct thread_data *, struct io_u **);
-extern long io_u_sync_complete(struct thread_data *, struct io_u *, endio_handler *);
-extern long io_u_queued_complete(struct thread_data *, int, endio_handler *);
+extern long __must_check io_u_sync_complete(struct thread_data *, struct io_u *, endio_handler *);
+extern long __must_check io_u_queued_complete(struct thread_data *, int, endio_handler *);
 extern void io_u_queued(struct thread_data *, struct io_u *);
 
 /*
  * io engine entry points
  */
-extern int td_io_init(struct thread_data *);
-extern int td_io_prep(struct thread_data *, struct io_u *);
-extern int td_io_queue(struct thread_data *, struct io_u *);
-extern int td_io_sync(struct thread_data *, struct fio_file *);
-extern int td_io_getevents(struct thread_data *, int, int, struct timespec *);
-extern int td_io_commit(struct thread_data *);
+extern int __must_check td_io_init(struct thread_data *);
+extern int __must_check td_io_prep(struct thread_data *, struct io_u *);
+extern int __must_check td_io_queue(struct thread_data *, struct io_u *);
+extern int __must_check td_io_sync(struct thread_data *, struct fio_file *);
+extern int __must_check td_io_getevents(struct thread_data *, int, int, struct timespec *);
+extern int __must_check td_io_commit(struct thread_data *);
 
 /*
  * This is a pretty crappy semaphore implementation, but with the use that fio
@@ -685,7 +685,7 @@
 #define FIO_IOOPS_VERSION	5
 
 extern struct ioengine_ops *load_ioengine(struct thread_data *, const char *);
-extern int register_ioengine(struct ioengine_ops *);
+extern void register_ioengine(struct ioengine_ops *);
 extern void unregister_ioengine(struct ioengine_ops *);
 extern void close_ioengine(struct thread_data *);
 
diff --git a/ioengines.c b/ioengines.c
index db33379..ab5b224 100644
--- a/ioengines.c
+++ b/ioengines.c
@@ -66,11 +66,10 @@
 	INIT_LIST_HEAD(&ops->list);
 }
 
-int register_ioengine(struct ioengine_ops *ops)
+void register_ioengine(struct ioengine_ops *ops)
 {
 	INIT_LIST_HEAD(&ops->list);
 	list_add_tail(&ops->list, &engine_list);
-	return 0;
 }
 
 static struct ioengine_ops *find_ioengine(const char *name)
diff --git a/os.h b/os.h
index a2699dd..da80fbd 100644
--- a/os.h
+++ b/os.h
@@ -54,4 +54,10 @@
 #define FIO_HUGE_PAGE			(4096 * 1024)
 #endif
 
+#if __GNUC__ < 3
+#define __must_check
+#else
+#define __must_check			__attribute__((warn_unused_result))
+#endif
+
 #endif