linux-kernel - Re: [PATCH v4 19/19] iommu: Remove detach

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Message-ID: <d0dafb48-9c3f-834a-abc6-52cdb8f3ebf6@linux.intel.com>
Date:   Thu, 5 Jan 2023 14:41:43 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     Jason Gunthorpe <jgg@...dia.com>
Cc:     baolu.lu@...ux.intel.com, Joerg Roedel <joro@...tes.org>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        Hector Martin <marcan@...can.st>,
        Sven Peter <sven@...npeter.dev>,
        Rob Clark <robdclark@...il.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Yong Wu <yong.wu@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        Orson Zhai <orsonzhai@...il.com>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Thierry Reding <thierry.reding@...il.com>,
        iommu@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 19/19] iommu: Remove detach_dev callback

On 2023/1/4 21:22, Jason Gunthorpe wrote:
> On Wed, Jan 04, 2023 at 08:57:25PM +0800, Lu Baolu wrote:
>> The detach_dev callback of domain ops is not called in the IOMMU core.
>> Remove this callback to avoid dead code. The trace event for detaching
>> domain from device is removed accordingly.
>>
>> Signed-off-by: Lu Baolu<baolu.lu@...ux.intel.com>
>> ---
>>   include/linux/iommu.h        |  2 --
>>   include/trace/events/iommu.h |  7 -------
>>   drivers/iommu/iommu-traces.c |  1 -
>>   drivers/iommu/iommu.c        | 29 +++++------------------------
>>   4 files changed, 5 insertions(+), 34 deletions(-)
>>
>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>> index 0d10566b3cb2..a8063f26ff69 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -299,7 +299,6 @@ struct iommu_ops {
>>    * * EBUSY	- device is attached to a domain and cannot be changed
>>    * * ENODEV	- device specific errors, not able to be attached
>>    * * <others>	- treated as ENODEV by the caller. Use is discouraged
>> - * @detach_dev: detach an iommu domain from a device
>>    * @set_dev_pasid: set an iommu domain to a pasid of device
>>    * @map: map a physically contiguous memory region to an iommu domain
>>    * @map_pages: map a physically contiguous set of pages of the same size to
>> @@ -320,7 +319,6 @@ struct iommu_ops {
>>    */
>>   struct iommu_domain_ops {
>>   	int (*attach_dev)(struct iommu_domain *domain, struct device *dev);
>> -	void (*detach_dev)(struct iommu_domain *domain, struct device *dev);
>>   	int (*set_dev_pasid)(struct iommu_domain *domain, struct device *dev,
>>   			     ioasid_t pasid);
>>   
>> diff --git a/include/trace/events/iommu.h b/include/trace/events/iommu.h
>> index 29096fe12623..70743db1fb75 100644
>> --- a/include/trace/events/iommu.h
>> +++ b/include/trace/events/iommu.h
>> @@ -76,13 +76,6 @@ DEFINE_EVENT(iommu_device_event, attach_device_to_domain,
>>   	TP_ARGS(dev)
>>   );
>>   
>> -DEFINE_EVENT(iommu_device_event, detach_device_from_domain,
>> -
>> -	TP_PROTO(struct device *dev),
>> -
>> -	TP_ARGS(dev)
>> -);
>> -
> did you want to add a trace for the set_platform_dma_ops in the
> earlier patch?

If necessary, we can add such a trace event. But I do hope to further
evolve the iommu drivers that need this callback. Finally, we should
remove it totally.

--
Best regards,
baolu