From: Lai Jiangshan <laijs@cn.fujitsu.com>
Date: Thu, 2 Apr 2009 07:16:56 +0000 (+0800)
Subject: tracing: disable seeking for trace_pipe_raw
X-Git-Tag: v2.6.30-rc2~75^2~10
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d1e7e02f30be672c6f6ee40908be83877a0d49d1;p=pandora-kernel.git

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>
---

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