Re: [PATCH 1/2] trace_events_filter: use rcu_assign_pointer() whensetting ftrace_event_call->filter

From: Tejun Heo
Date: Wed Nov 23 2011 - 12:33:19 EST


Hello, Steven.

On Wed, Nov 23, 2011 at 12:06:40PM -0500, Steven Rostedt wrote:
> > So, synchronized_sched() being called after isn't relevant. We want
> > smp_wmb() between data structure initialization and assignment of the
> > new pointer.
>
> Ah, you're saying that we need to guarantee that the allocated filter is
> seen before we update the call->filter to point to it. OK, fair enough,
> this does look like a bug fix.
>
> Is it big enough to be considered for stable?

It's unlikely to happen for x86 or arm and that probably is the
biggest reason there hasn't already been a bug report. It isn't very
urgent but at the same time the change is almost trivial, so marking
it for stable is a pretty safe bet. I lean toward marking it for
stable but the leaning isn't too strong. :)

Thanks.

--
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/