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    SubjectRe: [PATCH v2 2/5] metag: ftrace: fix the comments for ftrace_modify_code
    Hi Steven,

    On Wed, Dec 23, 2015 at 12:33:46PM -0500, Steven Rostedt wrote:
    > On Sun, 6 Dec 2015 10:02:55 +0800
    > Li Bin <huawei.libin@huawei.com> wrote:
    >
    > > There is no need to worry about module and __init text disappearing
    > > case, because that ftrace has a module notifier that is called when
    > > a module is being unloaded and before the text goes away and this
    > > code grabs the ftrace_lock mutex and removes the module functions
    > > from the ftrace list, such that it will no longer do any
    > > modifications to that module's text, the update to make functions
    > > be traced or not is done under the ftrace_lock mutex as well.
    > > And by now, __init section codes should not been modified
    > > by ftrace, because it is black listed in recordmcount.c and
    > > ignored by ftrace.
    > >
    > > Cc: James Hogan <james.hogan@imgtec.com>
    > > Cc: linux-metag@vger.kernel.org
    > > Suggested-by: Steven Rostedt <rostedt@goodmis.org>
    > > Signed-off-by: Li Bin <huawei.libin@huawei.com>
    >
    > Hi, can I get a metag maintainer to ack this. Or you can take the patch
    > too.

    Yep, sorry for the delay,

    Acked-by: James Hogan <james.hogan@imgtec.com>

    Cheers
    James

    >
    > -- Steve
    >
    > > ---
    > > arch/metag/kernel/ftrace.c | 11 +++++------
    > > 1 files changed, 5 insertions(+), 6 deletions(-)
    > >
    > > diff --git a/arch/metag/kernel/ftrace.c b/arch/metag/kernel/ftrace.c
    > > index ed1d685..ac8c039 100644
    > > --- a/arch/metag/kernel/ftrace.c
    > > +++ b/arch/metag/kernel/ftrace.c
    > > @@ -54,12 +54,11 @@ static int ftrace_modify_code(unsigned long pc, unsigned char *old_code,
    > > unsigned char replaced[MCOUNT_INSN_SIZE];
    > >
    > > /*
    > > - * Note: Due to modules and __init, code can
    > > - * disappear and change, we need to protect against faulting
    > > - * as well as code changing.
    > > - *
    > > - * No real locking needed, this code is run through
    > > - * kstop_machine.
    > > + * Note:
    > > + * We are paranoid about modifying text, as if a bug was to happen, it
    > > + * could cause us to read or write to someplace that could cause harm.
    > > + * Carefully read and modify the code with probe_kernel_*(), and make
    > > + * sure what we read is what we expected it to be before modifying it.
    > > */
    > >
    > > /* read the text we want to modify */
    >
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