From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from am1outboundpool.messaging.microsoft.com (am1ehsobe006.messaging.microsoft.com [213.199.154.209]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "Microsoft Secure Server Authority" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 6B895B6F62 for ; Thu, 29 Mar 2012 21:01:32 +1100 (EST) Received: from mail49-am1 (localhost [127.0.0.1]) by mail49-am1-R.bigfish.com (Postfix) with ESMTP id 3D0A32C02E5 for ; Thu, 29 Mar 2012 10:01:28 +0000 (UTC) Received: from AM1EHSMHS009.bigfish.com (unknown [10.3.201.254]) by mail49-am1.bigfish.com (Postfix) with ESMTP id C508524004C for ; Thu, 29 Mar 2012 10:01:25 +0000 (UTC) From: Huang Changming-R66093 To: "linuxppc-dev@ozlabs.org" Subject: why use 'raw_spin_lock_irqsave' inf function 'of_find_node_with_property' Date: Thu, 29 Mar 2012 10:01:22 +0000 Message-ID: <110EED8CC96DFC488B7E717A2027A27C05F5BA@039-SN1MPN1-003.039d.mgd.msft.net> Content-Type: multipart/alternative; boundary="_000_110EED8CC96DFC488B7E717A2027A27C05F5BA039SN1MPN1003039d_" MIME-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --_000_110EED8CC96DFC488B7E717A2027A27C05F5BA039SN1MPN1003039d_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Hi, all In function "of_find_node_with_property", why use "raw_spin_lock_irqsave" t= o disable preemption and disable interrupt? If enable them, what impact will be observed? This function just finds the node from the DTS file, it can't be interrupte= d or preempted? I have done one test: remove "raw_spin_lock_irqsave" and "raw_spin_unlock_i= rqrestore" from this function, It seems there is no any bad result, the Linux kernel still work well. Best Regards Jerry Huang --_000_110EED8CC96DFC488B7E717A2027A27C05F5BA039SN1MPN1003039d_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Hi, all

In function “of_find_node_with_property”= , why use “raw_spin_lock_irqsave” to disable preemption and dis= able interrupt?

If enable them, what impact will be observed?

This function just finds the node from the DTS file,= it can’t be interrupted or preempted?

I have done one test: remove “raw_spin_lock_ir= qsave” and “raw_spin_unlock_irqrestore” from this functio= n,

It seems there is no any bad result, the Linux kerne= l still work well.

Best Regards

Jerry Huang

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