linux-kernel - Re: [BUGFIX PATCH][RESEND] kexec & iosapic: kexec oops when iosapic was removed

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Message-ID: <502CCB38.1030705@huawei.com>
Date:	Thu, 16 Aug 2012 18:28:08 +0800
From:	Hanjun Guo <guohanjun@...wei.com>
To:	"Luck, Tony" <tony.luck@...el.com>
CC:	"Yu, Fenghua" <fenghua.yu@...el.com>,
	"linux-ia64@...r.kernel.org" <linux-ia64@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Jiang Liu <jiang.liu@...wei.com>,
	Eric Biederman <ebiederm@...ssion.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	Haren Myneni <hbabu@...ibm.com>,
	Toshi Kani <toshi.kani@...com>,
	Yinghai Lu <yinghai@...nel.org>,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	Taku Izumi <izumi.taku@...fujitsu.com>,
	Wen Congyang <wency@...fujitsu.com>,
	Tang Chen <tangchen@...fujitsu.com>,
	Jianguo Wu <wujianguo@...wei.com>
Subject: Re: [BUGFIX PATCH][RESEND] kexec & iosapic: kexec oops when iosapic
 was removed

On 2012/8/13 10:54, Luck, Tony wrote:
>> 		vec = irq_to_vector(irq);
>> 		list_for_each_entry(rte, &info->rtes,
>> 				rte_list) {
>> +			if (rte->refcnt == NO_REF_RTE)
>> +				continue;
>> +
>> 			iosapic_write(rte->iosapic,
>> 					IOSAPIC_RTE_LOW(rte->rte_index),
>> 					IOSAPIC_MASK|vec);
> 
> This will work - but is it papering over a problem when you removed the
> iosapic? Should we really have removed this "rte" from rte_list when the
> iosapic was removed?
> 
> -Tony
> 

Hi Tony,
    Thanks for your comments, and sorry for the late reply.

We only set rte->refcnt to NO_REF_RTE if no device attach to this RTE when
unregister a GSI, and increase the rte->refcnt if the RTE is already existing
when register a GSI, so "rte" will not removed from rte_list when the
iosapic is removed.

Actually, the rte_list will keep static when remove/add a existing iosapic
after boot up.

Should we remove the RTE from the rte_list? if yes, we will have more
to do than this patch.

Thanks
Hanjun Guo

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