---

yaml
---
r: 140856
b: refs/heads/master
c: 2dc5d12
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 4f3640f8a358f2183a8c966f299eeb55ca523e06
+refs/heads/master: 2dc5d12b1f43134e9bc5037f69f4739cfdfab93e

trunk/kernel/trace/trace.c

@@ -346,16 +346,21 @@ ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
 	int len;
 	int ret;
 
+	if (!cnt)
+		return 0;
+
 	if (s->len <= s->readpos)
 		return -EBUSY;
 
 	len = s->len - s->readpos;
 	if (cnt > len)
 		cnt = len;
 	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
-	if (ret)
+	if (ret == cnt)
 		return -EFAULT;
 
+	cnt -= ret;
+
 	s->readpos += len;
 	return cnt;
 }
@@ -3049,6 +3054,9 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
 	ssize_t ret;
 	size_t size;
 
+	if (!count)
+		return 0;
+
 	/* Do we have previous read data to read? */
 	if (info->read < PAGE_SIZE)
 		goto read;
@@ -3073,8 +3081,10 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
 		size = count;
 
 	ret = copy_to_user(ubuf, info->spare + info->read, size);
-	if (ret)
+	if (ret == size)
 		return -EFAULT;
+	size -= ret;
+
 	*ppos += size;
 	info->read += size;