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From: Thomas Gleixner <tglx@linutronix.de>
To: Dou Liyang <douly.fnst@cn.fujitsu.com>
Cc: Kees Cook <keescook@chromium.org>,
	re.emese@gmail.com, Marc Zyngier <marc.zyngier@arm.com>,
	linux-kernel@vger.kernel.org
Subject: Re: irqdesc: Why the "__ref" is needed in __irq_alloc_descs() ?
Date: Fri, 9 Mar 2018 12:39:53 +0100 (CET)	[thread overview]
Message-ID: <alpine.DEB.2.21.1803091237320.1364@nanos.tec.linutronix.de> (raw)
In-Reply-To: <9246951e-9cf5-6a3f-5cf4-2d3aaff03026@cn.fujitsu.com>

On Fri, 9 Mar 2018, Dou Liyang wrote:
> I have a question about "__ref" in Linux kernel.
> 
> When I looked into the __irq_alloc_descs(), I found it tagged a
> "__ref" mark, but I didn't find that it referenced code or data
> from init section.

See the various

#define irq_alloc_desc* 

variants. That will give you enough use cases from init.

> And after I tested, seems "__ref" just puts the code into a different
> section that is not checked by modpost. It does not affect the
> performance whether it is tagged or not. Is it right?

Well having code in a different section can cause performance issues, but
that only matters in a hotpath. irq_alloc_desc* is not performance critical
at all, so nothing to worry about.

Thanks,

	tglx

      reply	other threads:[~2018-03-09 11:40 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-09  7:07 Dou Liyang
2018-03-09 11:39 ` Thomas Gleixner [this message]

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