linux-kernel - Re: [PATCH v3 03/28] x86/sgx: Add 'struct sgx_epc_lru

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Date:   Mon, 17 Jul 2023 08:23:00 -0500
From:   "Haitao Huang" <haitao.huang@...ux.intel.com>
To:     dave.hansen@...ux.intel.com, tj@...nel.org,
        linux-kernel@...r.kernel.org, linux-sgx@...r.kernel.org,
        cgroups@...r.kernel.org, "Thomas Gleixner" <tglx@...utronix.de>,
        "Ingo Molnar" <mingo@...hat.com>, "Borislav Petkov" <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        "Jarkko Sakkinen" <jarkko@...nel.org>
Cc:     kai.huang@...el.com, reinette.chatre@...el.com,
        "Kristen Carlson Accardi" <kristen@...ux.intel.com>,
        zhiquan1.li@...el.com, seanjc@...gle.com
Subject: Re: [PATCH v3 03/28] x86/sgx: Add 'struct sgx_epc_lru_lists' to
 encapsulate lru list(s)

On Mon, 17 Jul 2023 07:45:36 -0500, Jarkko Sakkinen <jarkko@...nel.org>  
wrote:

> On Wed Jul 12, 2023 at 11:01 PM UTC, Haitao Huang wrote:
>> From: Kristen Carlson Accardi <kristen@...ux.intel.com>
>>
>> Introduce a data structure to wrap the existing reclaimable list
>> and its spinlock in a struct to minimize the code changes needed
>> to handle multiple LRUs as well as reclaimable and non-reclaimable
>> lists. The new structure will be used in a following set of patches to
>> implement SGX EPC cgroups.
>>
>> The changes to the structure needed for unreclaimable lists will be
>> added in later patches.
>>
>> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
>> Signed-off-by: Kristen Carlson Accardi <kristen@...ux.intel.com>
>> Signed-off-by: Haitao Huang <haitao.huang@...ux.intel.com>
>> Cc: Sean Christopherson <seanjc@...gle.com>
>>
>> V3:
>> Removed the helper functions and revised commit messages
>> ---
>>  arch/x86/kernel/cpu/sgx/sgx.h | 17 +++++++++++++++++
>>  1 file changed, 17 insertions(+)
>>
>> diff --git a/arch/x86/kernel/cpu/sgx/sgx.h  
>> b/arch/x86/kernel/cpu/sgx/sgx.h
>> index f6e3c5810eef..77fceba73a25 100644
>> --- a/arch/x86/kernel/cpu/sgx/sgx.h
>> +++ b/arch/x86/kernel/cpu/sgx/sgx.h
>> @@ -92,6 +92,23 @@ static inline void *sgx_get_epc_virt_addr(struct  
>> sgx_epc_page *page)
>>  	return section->virt_addr + index * PAGE_SIZE;
>>  }
>>
>> +/*
>> + * This data structure wraps a list of reclaimable EPC pages, and a  
>> list of
>> + * non-reclaimable EPC pages and is used to implement a LRU policy  
>> during
>> + * reclamation.
>> + */
>> +struct sgx_epc_lru_lists {
>> +	/* Must acquire this lock to access */
>> +	spinlock_t lock;
>
> Isn't this self-explanatory, why the inline comment?

I got a warning from the checkpatch script complaining this lock needs  
comments.

Thanks
Haitao