---

yaml
---
r: 117999
b: refs/heads/master
c: 76aefee
h: refs/heads/master
i:
  117997: 27b27c9
  117995: a0d6bfe
  117991: 451ff52
  117983: 7caff22
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 593eb8a2d63e95772a5f22d746f18a997c5ee463
+refs/heads/master: 76aefee57657428fb77cbd8624119c1a440bee44

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;