1 files changed, 21 insertions, 15 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9d28476..1ce5dc6 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3277,19 +3277,13 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp)
 
 	info->tr	= &global_trace;
 	info->cpu	= cpu;
-	info->spare	= ring_buffer_alloc_read_page(info->tr->buffer);
+	info->spare	= NULL;
 	/* Force reading ring buffer for first read */
 	info->read	= (unsigned int)-1;
-	if (!info->spare)
-		goto out;
 
 	filp->private_data = info;
 
-	return 0;
-
- out:
-	kfree(info);
-	return -ENOMEM;
+	return nonseekable_open(inode, filp);
 }
 
 static ssize_t
@@ -3304,6 +3298,11 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
 	if (!count)
 		return 0;
 
+	if (!info->spare)
+		info->spare = ring_buffer_alloc_read_page(info->tr->buffer);
+	if (!info->spare)
+		return -ENOMEM;
+
 	/* Do we have previous read data to read? */
 	if (info->read < PAGE_SIZE)
 		goto read;
@@ -3342,7 +3341,8 @@ static int tracing_buffers_release(struct inode *inode, struct file *file)
 {
 	struct ftrace_buffer_info *info = file->private_data;
 
-	ring_buffer_free_read_page(info->tr->buffer, info->spare);
+	if (info->spare)
+		ring_buffer_free_read_page(info->tr->buffer, info->spare);
 	kfree(info);
 
 	return 0;
@@ -3428,14 +3428,19 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 	int size, i;
 	size_t ret;
 
-	/*
-	 * We can't seek on a buffer input
-	 */
-	if (unlikely(*ppos))
-		return -ESPIPE;
+	if (*ppos & (PAGE_SIZE - 1)) {
+		WARN_ONCE(1, "Ftrace: previous read must page-align\n");
+		return -EINVAL;
+	}
 
+	if (len & (PAGE_SIZE - 1)) {
+		WARN_ONCE(1, "Ftrace: splice_read should page-align\n");
+		if (len < PAGE_SIZE)
+			return -EINVAL;
+		len &= PAGE_MASK;
+	}
 
-	for (i = 0; i < PIPE_BUFFERS && len; i++, len -= size) {
+	for (i = 0; i < PIPE_BUFFERS && len; i++, len -= PAGE_SIZE) {
 		struct page *page;
 		int r;
 
@@ -3474,6 +3479,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 		spd.partial[i].offset = 0;
 		spd.partial[i].private = (unsigned long)ref;
 		spd.nr_pages++;
+		*ppos += PAGE_SIZE;
 	}
 
 	spd.nr_pages = i;