Re: [PATCH v2 15/15] kprobes: Free kretprobe_instance with rcu callback

Masami Hiramatsu
2020-08-27T12:14:43Z

On Thu, 27 Aug 2020 13:48:07 +0200
peterz@infradead.org wrote:

> On Thu, Aug 27, 2020 at 08:37:49PM +0900, Masami Hiramatsu wrote:
> > Free kretprobe_instance with rcu callback instead of directly
> > freeing the object in the kretprobe handler context.
> >
> > This will make kretprobe run safer in NMI context.
> >
> > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> > ---
> > include/linux/kprobes.h | 3 ++-
> > kernel/kprobes.c | 25 ++++++-------------------
> > 2 files changed, 8 insertions(+), 20 deletions(-)
> >
> > diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
> > index 46a7afcf5ec0..97557f820d9b 100644
> > --- a/include/linux/kprobes.h
> > +++ b/include/linux/kprobes.h
> > @@ -160,6 +160,7 @@ struct kretprobe_instance {
> > struct kretprobe *rp;
> > kprobe_opcode_t *ret_addr;
> > struct task_struct *task;
> > + struct rcu_head rcu;
> > void *fp;
> > char data[];
> > };
>
> You can stick the rcu_head in a union with hlist.

Indeed. OK, I'll update it.

Thank you!

--
Masami Hiramatsu <mhiramat@kernel.org>