Re: [PATCH] perf core: Get rid of 'uses dynamic stack allocation' warning

Path	csiph.com!aioe.org!bofh.it!news.nic.it!robomod
From	"Wangnan (F)" <wangnan0@huawei.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] perf core: Get rid of 'uses dynamic stack allocation' warning
Date	Fri, 22 Jan 2016 09:10:02 +0100
Message-ID	<qTEX8-1ic-17@gated-at.bofh.it> (permalink)
References	<qTDRo-hX-13@gated-at.bofh.it> <qTEX8-1ic-7@gated-at.bofh.it>
User-Agent	Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0
MIME-Version	1.0
Content-Type	text/plain; charset="utf-8"; format=flowed
Content-Transfer-Encoding	7bit
X-Originating-IP	[10.111.66.109]
X-Cfilter-Loop	Reflected
X-Mirapoint-Virus-Rapid-Raw	score=unknown(0), refid=str=0001.0A020204.56A1E306.0147,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32
X-Mirapoint-Loop-ID	1634a19e9994317dfd874b1f6c62cf07
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	26
Organization	linux.* mail to news gateway
X-Original-Cc	<linux-kernel@vger.kernel.org>, <pi3orama@163.com>
X-Original-Date	Fri, 22 Jan 2016 16:06:25 +0800
X-Original-Message-ID	<56A1E301.2080409@huawei.com>
X-Original-References	<1453445521-230804-1-git-send-email-wangnan0@huawei.com> <20160122080004.GN6357@twins.programming.kicks-ass.net>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1314820

Show key headers only | View raw

On 2016/1/22 16:00, Peter Zijlstra wrote:
> On Fri, Jan 22, 2016 at 06:52:01AM +0000, Wang Nan wrote:
>> On s390 with CONFIG_WARN_DYNAMIC_STACK set, 'uses dynamic stack
>> allocation' warning is issued when defining 'struct perf_sample_data'
>> local variable.
>>
>> This patch suppress this warning by allocating extra 255 bytes and
>> compute aligned pointer manually.
> I've seen the warning and always wondered wtf it was about. This
> Changelog doesn't actually explain what the problem is, so I cannot
> judge the solution.
>
> That said, 255 extra bytes does sound excessive just to avoid a warn.

OK. Then I happly ignore it.

I also don't know the exact reason.  I guess it related
to the ____cacheline_aligned decorator after 'struct
perf_sample_data'. When allocating that structure on the
stack, kernel has to dynamically compute the stack size it
need to satisify the alignment constrain. My patch does
this work manually.

Thank you.

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH] perf core: Get rid of 'uses dynamic stack allocation' warning Wang Nan <wangnan0@huawei.com> - 2016-01-22 08:00 +0100
  Re: [PATCH] perf core: Get rid of 'uses dynamic stack allocation'  warning kbuild test robot <lkp@intel.com> - 2016-01-22 08:10 +0100
  Re: [PATCH] perf core: Get rid of 'uses dynamic stack allocation'  warning Peter Zijlstra <peterz@infradead.org> - 2016-01-22 09:10 +0100
    Re: [PATCH] perf core: Get rid of 'uses dynamic stack allocation'  warning "Wangnan (F)" <wangnan0@huawei.com> - 2016-01-22 09:10 +0100

csiph-web