tracing: disable seeking for trace_pipe_raw

Impact: disable pread()

We set tracing_buffers_fops.llseek to no_llseek,
but we can still perform pread() to read this file.

That is not expected.

This fix uses nonseekable_open() to disable it.

tracing_buffers_fops.llseek is still set to no_llseek,
it mark this file is a "non-seekable device" and is used by
sys_splice(). See also do_splice() or manual of splice(2):

ERRORS
       EINVAL Target file system doesn't support  splicing;
              neither  of the descriptors refers to a pipe;
              or offset given for non-seekable device.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49D46668.8030806@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9d28476..24b0168 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3285,7 +3285,7 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp)
 
        filp->private_data = info;
 
-       return 0;
+       return nonseekable_open(inode, filp);
 
  out:
        kfree(info);