Re: [PATCH 1/5] ftrace: use module notifier for function tracer

[Masami Hiramatsu <mhiramat@redhat.com>]

Tim Abbott wrote:
> The reason that we want to export text_mutex is that it can be useful for 
> the Ksplice core (still kernel/ksplice.c) to be built as a module.  This 
> is desirable when a different version of the kernel/ksplice.c code is 
> needed in order to apply a particular update (e.g. because there was a bug 
> in Ksplice).

Ah, OK. Certainly, Ksplice can't patch itself. It might be a good reason for
exporting text_mutex.


> I agree that great care should be taken when writing code that patches the 
> kernel's text.  However, I don't think failing to export text_mutex to GPL 
> modules helps ensure that.  In particular, not exporting text_mutex 
> doesn't prevent modules from patching the kernel text.  It just prevents 
> any modules that do so from grabbing the appropriate lock.

What I'm concerned about exporting locking staffs is that may cause
a dead lock. However, we've already exported module_mutex.
I don't think that exporting text_mutex is more considerable than that. :-)

Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com