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Message-ID: <28a58a21-a866-b49c-9977-c8d05b320fbd@linux.intel.com>
Date:   Thu, 7 Jul 2022 08:20:32 +0800
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Cc:     baolu.lu@linux.intel.com, will@kernel.org, iommu@lists.linux.dev,
        linux-arm-kernel@lists.infradead.org,
        suravee.suthikulpanit@amd.com, vasant.hegde@amd.com,
        mjrosato@linux.ibm.com, gerald.schaefer@linux.ibm.com,
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        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 03/15] iommu: Always register bus notifiers
Content-Language: en-US
To:     Robin Murphy <robin.murphy@arm.com>, joro@8bytes.org
References: <cover.1657034827.git.robin.murphy@arm.com>
 <8c380309f264cd0dfc73ba2ec060adc9515af2f2.1657034828.git.robin.murphy@arm.com>
 <1fab4c8a-7bc5-9a50-d48a-0dc590cac7a6@linux.intel.com>
 <3d613192-f673-852e-9c52-b8a913d25616@arm.com>
From:   Baolu Lu <baolu.lu@linux.intel.com>
In-Reply-To: <3d613192-f673-852e-9c52-b8a913d25616@arm.com>
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On 2022/7/6 21:43, Robin Murphy wrote:
> On 2022-07-06 02:53, Baolu Lu wrote:
>> On 2022/7/6 01:08, Robin Murphy wrote:
>>>   /*
>>>    * Use a function instead of an array here because the domain-type 
>>> is a
>>>    * bit-field, so an array would waste memory.
>>> @@ -152,6 +172,10 @@ static int __init iommu_subsys_init(void)
>>>               (iommu_cmd_line & IOMMU_CMD_LINE_STRICT) ?
>>>                   "(set via kernel command line)" : "");
>>> +    /* If the system is so broken that this fails, it will WARN 
>>> anyway */
>>
>> Can you please elaborate a bit on this? iommu_bus_init() still return
>> errors.
> 
> Indeed, it's commenting on the fact that we don't try to clean up or 
> propagate an error value further even if it did ever manage to return 
> one. I feared that if I strip the error handling out of iommu_bus_init() 
> itself on the same reasoning, we'll just get constant patches from the 
> static checker brigade trying to add it back, so it seemed like the 
> neatest compromise to keep that decision where it's obviously in an 
> early initcall, rather than in the helper function which can be viewed 
> out of context. However, I'm happy to either expand this comment or go 
> the whole way and make iommu_bus_init() return void if you think it's 
> worthwhile.

Thanks for the explanation. It would be helpful if the comment could be
expanded. In this case, after a long time, people will not consider it
an oversight. :-)

Best regards,
baolu

> 
> Cheers,
> Robin.
> 
>>
>>> +    for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++)
>>> +        iommu_bus_init(iommu_buses[i]);
>>> +
>>>       return 0;
>>
>> Best regards,
>> baolu
>