On Thu, Dec 03, 2015 at 10:05:25AM -0500, Steven Rostedt wrote: > On Thu, 3 Dec 2015 09:38:21 +0000 > Will Deacon <[email protected]> wrote: > > I think you're missing the case where the instruction changes under our > > feet after we've read it but before we've replaced it (e.g. due to module > > unloading). I think that's why ftrace_modify_code has the comment about > > lack of locking thanks to stop_machine. > > Note, ftrace has a module notifier that is called when a module is > being unloaded and before the text goes away. 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 is done under the ftrace_lock > mutex as well. > > You do not need to worry about module text disappearing from > underneath you while you do your modifications.
Good. > Now, if there's comments that suggest otherwise, they need to be > updated. Yeah, I think the comments on x86 and arm64 are out of date. They also mention the freeing of __init sections -- is that still a concern? Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
