linux-kernel - Re: [PATCH 1/1] iommu/vt-d: Fix possible recursive locking in intel_iommu

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Message-ID: <8e970367-746e-0e74-ba39-e941fdbfdab7@linux.intel.com>
Date:   Sun, 24 Jul 2022 10:59:34 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     "Tian, Kevin" <kevin.tian@...el.com>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>
Cc:     baolu.lu@...ux.intel.com, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] iommu/vt-d: Fix possible recursive locking in
 intel_iommu_init()

Hi Kevin,

On 2022/7/21 15:39, Tian, Kevin wrote:
>> From: Lu Baolu <baolu.lu@...ux.intel.com>
>> Sent: Tuesday, July 19, 2022 7:53 AM
>>
>> @@ -88,7 +89,8 @@ extern struct list_head dmar_drhd_units;
>>   static inline bool dmar_rcu_check(void)
>>   {
>>   	return rwsem_is_locked(&dmar_global_lock) ||
>> -	       system_state == SYSTEM_BOOTING;
>> +	       system_state == SYSTEM_BOOTING ||
>> +	       (IS_ENABLED(CONFIG_INTEL_IOMMU)
>> && !intel_iommu_enabled);
>>   }
> 
> intel_iommu_enabled is 0 if CONFIG_INTEL_IOMMU is not set.
> 
> same for other similar checks.

Sorry that I didn't get your point. If CONFIG_INTEL_IOMMU is not set,
IS_ENABLED(CONFIG_INTEL_IOMMU) is 0. The adding check has no effect. Did
I miss anything?

Best regards,
baolu