Subject: Re: [PATCH v6 3/4] bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter

From: Alexei Starovoitov <[email-masked]>
Date: Wed, 5 Aug 2015 09:00:43 -0700

On 8/5/15 3:15 AM, Peter Zijlstra wrote:
> On Wed, Aug 05, 2015 at 12:04:25PM +0200, Peter Zijlstra wrote:
>> On Tue, Aug 04, 2015 at 08:58:15AM +0000, Kaixu Xia wrote:
>
>>> +	    event->ctx->task != current)
>
> Strictly speaking we should hold rcu_read_lock around dereferencing
> event->ctx (or have IRQs disabled -- although I know Paul doesn't like
> us relying on that).

programs are always executing under rcu_read_lock, so we should be good
here too.