ring-buffer: Move zeroing out excess in page to ring buffer code

Currently the trace splice code zeros out the excess bytes in the page before
sending it off to userspace.

This is to make sure userspace is not getting anything it should not be
when reading the pages, because the excess data was never initialized
to zero before writing (for perfomance reasons).

But the splice code has no business in doing this work, it should be
done by the ring buffer. With the latest changes for recording lost
events, the splice code gets it wrong anyway.

Move the zeroing out of excess bytes into the ring buffer code.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 0 insertions, 6 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ba0ec81158b2..95d0b1a28f93 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3661,7 +3661,6 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
                      size_t count, loff_t *ppos)
 {
         struct ftrace_buffer_info *info = filp->private_data;
-        unsigned int pos;
         ssize_t ret;
         size_t size;
 
@@ -3688,11 +3687,6 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
         if (ret < 0)
                 return 0;
 
-        pos = ring_buffer_page_len(info->spare);
-
-        if (pos < PAGE_SIZE)
-                memset(info->spare + pos, 0, PAGE_SIZE - pos);
-
 read:
         size = PAGE_SIZE - info->read;
         if (size > count)