From c072c24975ec4f0ccfcb6f5c8a8040b6eb75ef8f Mon Sep 17 00:00:00 2001
From: walimis <walimisdev@gmail.com>
Date: Fri, 28 Nov 2008 12:21:19 +0800
Subject: [PATCH] ftrace: improve documentation

Impact: extend documentation with notice of using wild cards correctly

We know that we can use wild cards to set set_ftrace_filter, but there's
problem when using them naively such as:

   echo h* > /debug/tracing/set_ftrace_filter

If there are files named with "h" prefix in current directory,
echo "h*" will echo these filenames to set_ftrace_filter, not the
intended "h*".

For example:

  $ cat /debug/tracing/available_filter_functions |grep ^hr |wc -l
  23
  $ ls
  $ touch hraa hrdd
  $ ls
  hraa  hrdd
  $ echo hr* > /debug/tracing/set_ftrace_filter
  $ cat /debug/tracing/set_ftrace_filter

No output in /debug/tracing/set_ftrace_filter!

If we use '' to escape wild cards, it works:

  $ ls
  hraa  hrdd
  $ echo "hr*" > /debug/tracing/set_ftrace_filter
  $ cat /debug/tracing/set_ftrace_filter |wc -l
  23

This problem can lead to unexpected result if current directory has a
lot of files.

Signed-off-by: walimis <walimisdev@gmail.com>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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