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

From	Jon Christopherson <jon@jons.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] tools/perf, rbtree: Add RCU wrappers to make rbtree.h usable in user-space
Date	2015-07-03 12:10 +0200
Message-ID	<pI64V-7ct-9@gated-at.bofh.it> (permalink)
References	(2 earlier) <pHD2V-5G5-11@gated-at.bofh.it> <pHMIX-3df-33@gated-at.bofh.it> <pHMIX-3df-31@gated-at.bofh.it> <pHXbj-1sI-7@gated-at.bofh.it> <pI3qp-5w3-7@gated-at.bofh.it>
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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
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Thread

[PATCH 2/2 block/for-linus] writeback: don't drain  bdi_writeback_congested on bdi destruction Tejun Heo <tj@kernel.org> - 2015-07-02 03:00 +0200
  Re: [PATCH] tools/perf, rbtree: Add RCU wrappers to make rbtree.h  usable in user-space Tejun Heo <tj@kernel.org> - 2015-07-02 15:30 +0200
    Re: [PATCH] tools/perf, rbtree: Add RCU wrappers to make rbtree.h usable in user-space Rusty Russell <rusty@rustcorp.com.au> - 2015-07-03 02:40 +0200
      Re: [PATCH] tools/perf, rbtree: Add RCU wrappers to make rbtree.h  usable in user-space Jon Christopherson <jon@jons.org> - 2015-07-03 12:10 +0200
      Re: [PATCH] tools/perf, rbtree: Add RCU wrappers to make rbtree.h  usable in user-space Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-07-05 10:50 +0200
  Re: [PATCH 2/2 block/for-linus] writeback: don't drain bdi_writeback_congested  on bdi destruction Jens Axboe <axboe@kernel.dk> - 2015-07-02 16:10 +0200

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