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    Subject[PATCH 04/12 v3] ftrace: comment arch ftrace code
    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 15:23:20.000000000 -0400
    +++ linux-compile.git/arch/x86/kernel/ftrace.c 2008-10-22 15:24:15.000000000 -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 -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;
    --


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