[PATCH 04/11] ftrace: comment arch ftrace code

[Steven Rostedt <rostedt@goodmis.org>]

[-- Attachment #1: ftrace-comment-mod-code.patch --]
[-- Type: text/plain, Size: 1329 bytes --]

Add comments to explain what is happening in the x86 arch ftrace code.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 arch/x86/kernel/ftrace.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Index: linux-compile.git/arch/x86/kernel/ftrace.c
===================================================================
--- linux-compile.git.orig/arch/x86/kernel/ftrace.c	2008-10-22 13:15:36.000000000 -0400
+++ linux-compile.git/arch/x86/kernel/ftrace.c	2008-10-22 13:16:35.000000000 -0400
@@ -66,18 +66,23 @@ ftrace_modify_code(unsigned long ip, uns
 	/*
 	 * Note: Due to modules and __init, code can
 	 *  disappear and change, we need to protect against faulting
-	 *  as well as code changing.
+	 *  as well as code changing. We do this by using the
+	 *  __copy_*_user functions.
 	 *
 	 * No real locking needed, this code is run through
 	 * kstop_machine, or before SMP starts.
 	 */
+
+	/* read the text we want to modify */
 	if (__copy_from_user_inatomic(replaced, (char __user *)ip,
 				      MCOUNT_INSN_SIZE))
 		return -1;
 
+	/* Make sure it is what we expect it to be */
 	if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
 		return -1;
 
+	/* replace the text with the new text */
 	if (__copy_to_user_inatomic((char __user *)ip, new_code,
 				    MCOUNT_INSN_SIZE))
 		return -1;

--