From 662b54a265e5aaa83bd820090842d49629f434d6 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt@goodmis.org>
Date: Thu, 23 Oct 2008 09:33:00 -0400
Subject: [PATCH] --- yaml --- r: 117999 b: refs/heads/master c:
 76aefee57657428fb77cbd8624119c1a440bee44 h: refs/heads/master i:   117997:
 27b27c94448fb38ad42509a4e83e710ece417f20   117995:
 a0d6bfe399671b6d9f4ccb172f5d4bde6d1a10e6   117991:
 451ff5221c883ac45259adeb912fa351a95aed48   117983:
 7caff22d22276a15f7ae9fd2392df4adce4f6250 v: v3

---
 [refs]                         | 2 +-
 trunk/arch/x86/kernel/ftrace.c | 7 ++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index 242d2580e16d..e31bf7965729 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 593eb8a2d63e95772a5f22d746f18a997c5ee463
+refs/heads/master: 76aefee57657428fb77cbd8624119c1a440bee44
diff --git a/trunk/arch/x86/kernel/ftrace.c b/trunk/arch/x86/kernel/ftrace.c
index 428291581cb2..783455454d78 100644
--- a/trunk/arch/x86/kernel/ftrace.c
+++ b/trunk/arch/x86/kernel/ftrace.c
@@ -66,18 +66,23 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
 	/*
 	 * 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 -EFAULT;
 
+	/* Make sure it is what we expect it to be */
 	if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
 		return -EINVAL;
 
+	/* replace the text with the new text */
 	if (__copy_to_user_inatomic((char __user *)ip, new_code,
 				    MCOUNT_INSN_SIZE))
 		return -EPERM;