staging: sync: Dump sync state to console on timeout

If we hit a timeout, dump sync state to console

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: Add commit message, whitespace fixups]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/android/sync.c

@@ -31,6 +31,7 @@
 static void sync_fence_signal_pt(struct sync_pt *pt);
 static int _sync_pt_has_signaled(struct sync_pt *pt);
 static void sync_fence_free(struct kref *kref);
+static void sync_dump(void);
 
 static LIST_HEAD(sync_timeline_list_head);
 static DEFINE_SPINLOCK(sync_timeline_list_lock);
@@ -574,8 +575,10 @@ int sync_fence_wait(struct sync_fence *fence, long timeout)
 	if (fence->status < 0)
 		return fence->status;
 
-	if (fence->status == 0)
+	if (fence->status == 0) {
+		sync_dump();
 		return -ETIME;
+	}
 
 	return 0;
 }
@@ -914,7 +917,34 @@ static __init int sync_debugfs_init(void)
 	debugfs_create_file("sync", S_IRUGO, NULL, NULL, &sync_debugfs_fops);
 	return 0;
 }
-
 late_initcall(sync_debugfs_init);
 
+#define DUMP_CHUNK 256
+static char sync_dump_buf[64 * 1024];
+void sync_dump(void)
+{
+	struct seq_file s = {
+		.buf = sync_dump_buf,
+		.size = sizeof(sync_dump_buf) - 1,
+	};
+	int i;
+
+	sync_debugfs_show(&s, NULL);
+
+	for (i = 0; i < s.count; i += DUMP_CHUNK) {
+		if ((s.count - i) > DUMP_CHUNK) {
+			char c = s.buf[i + DUMP_CHUNK];
+			s.buf[i + DUMP_CHUNK] = 0;
+			pr_cont("%s", s.buf + i);
+			s.buf[i + DUMP_CHUNK] = c;
+		} else {
+			s.buf[s.count] = 0;
+			pr_cont("%s", s.buf + i);
+		}
+	}
+}
+#else
+static void sync_dump(void)
+{
+}
 #endif