1 files changed, 21 insertions, 15 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9d28476a9851..1ce5dc6372b8 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;