staging: sync: Change wait timeout to mirror poll semantics

Change wait timeout to act like poll

Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: Erik Gilling <konkers@android.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Rob Clark <robclark@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: dri-devel@lists.freedesktop.org
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Erik Gilling <konkers@android.com>
[jstultz: Added commit message, squished typo-fix]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/android/sync.c

@@ -557,14 +557,14 @@ EXPORT_SYMBOL(sync_fence_cancel_async);
 
 int sync_fence_wait(struct sync_fence *fence, long timeout)
 {
-	int err;
+	int err = 0;
 
-	if (timeout) {
+	if (timeout > 0) {
 		timeout = msecs_to_jiffies(timeout);
 		err = wait_event_interruptible_timeout(fence->wq,
 						       fence->status != 0,
 						       timeout);
-	} else {
+	} else if (timeout < 0) {
 		err = wait_event_interruptible(fence->wq, fence->status != 0);
 	}
 

drivers/staging/android/sync.h

@@ -329,8 +329,8 @@ int sync_fence_cancel_async(struct sync_fence *fence,
  * @fence:	fence to wait on
  * @tiemout:	timeout in ms
  *
- * Wait for @fence to be signaled or have an error.  Waits indefintly
- * if @timeout = 0
+ * Wait for @fence to be signaled or have an error.  Waits indefinitely
+ * if @timeout < 0
  */
 int sync_fence_wait(struct sync_fence *fence, long timeout);
 
@@ -389,9 +389,9 @@ struct sync_fence_info_data {
 /**
  * DOC: SYNC_IOC_WAIT - wait for a fence to signal
  *
- * pass timeout in milliseconds.
+ * pass timeout in milliseconds.  Waits indefinitely timeout < 0.
  */
-#define SYNC_IOC_WAIT		_IOW(SYNC_IOC_MAGIC, 0, __u32)
+#define SYNC_IOC_WAIT		_IOW(SYNC_IOC_MAGIC, 0, __s32)
 
 /**
  * DOC: SYNC_IOC_MERGE - merge two fences