Re: [PATCH] tools/perf, rbtree: Add RCU wrappers to make rbtree.h usable in user-space

[Jon Christopherson <jon@jons.org>]

On 07/03/2015 02:14 AM, Peter Zijlstra wrote:
> On Fri, Jul 03, 2015 at 06:21:12AM +0930, Rusty Russell wrote:
>> Looks like Peter Zijlstra is the one to take this fix...
>
> acme is the steward of tools/perf/

This is the full context of the patch mentioned:

https://lkml.org/lkml/2015/6/17/129

>
>>>> diff --git a/tools/perf/util/include/linux/rcupdate.h
>>>> b/tools/perf/util/include/linux/rcupdate.h
>>>> new file mode 100644
>>>> index 0000000..51c0f45
>>>> --- /dev/null
>>>> +++ b/tools/perf/util/include/linux/rcupdate.h
>>>> @@ -0,0 +1,9 @@
>>>> +#ifndef PERF_LINUX_RCUPDATE_H_
>>>> +#define PERF_LINUX_RCUPDATE_H_
>>>> +
>>>> +/* Simple trivial wrappers for now, we don't use RCU in perf user-space
>>>> (yet): */
>>>> +#define WRITE_ONCE(var, val) ((var) = (val))
>
> It looks like perf includes linux/compiler.h so it should already have this.
>
>>>> +#define rcu_assign_pointer(ptr, val) WRITE_ONCE(ptr, val)
>
> That's plain wrong, WRITE_ONCE(*(ptr), (val))
>

The original author of the patch appears to be Ingo. Syntax aside .. it 
solves the issue mentioned. Perhaps a corrected version could be 
included instead.

-Jon