Re: [PATCH] perf: Fix RCU dereference check in perf_event_comm

[Peter Zijlstra]

On Thu, 2012-03-22 at 01:43 +0200, Ari Savolainen wrote:
> The warning below is printed when executing a command like
> sudo perf record su - user -c "echo hello"
> 
> It's fixed by moving the call of perf_event_comm to be protected
> by the task lock.

That seems like a rather poor solution since it increases the lock hold
time for no explained reason.

> include/linux/cgroup.h:567 suspicious rcu_dereference_check() usage!

>  [<ffffffff8109be55>] lockdep_rcu_suspicious+0xe5/0x100
>  [<ffffffff811131fa>] perf_event_comm+0x37a/0x4d0

So where exactly is this, perf_event_comm_event() takes rcu_read_lock()
so I presume its before that.
--
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/