netdev - Re: [PATCH net] net/smc: Remove validation of reserved bits in CLC Decline message

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Message-ID: <aLZtraICmwOQAtsO@linux.alibaba.com>
Date: Tue, 2 Sep 2025 12:08:13 +0800
From: Dust Li <dust.li@...ux.alibaba.com>
To: Mahanta Jambigi <mjambigi@...ux.ibm.com>, andrew+netdev@...n.ch,
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, alibuda@...ux.alibaba.com, sidraya@...ux.ibm.com,
	wenjia@...ux.ibm.com
Cc: pasic@...ux.ibm.com, horms@...nel.org, tonylu@...ux.alibaba.com,
	guwen@...ux.alibaba.com, netdev@...r.kernel.org,
	linux-s390@...r.kernel.org, linux-rdma@...r.kernel.org,
	Alexandra Winter <wintera@...ux.ibm.com>
Subject: Re: [PATCH net] net/smc: Remove validation of reserved bits in CLC
 Decline message

On 2025-09-01 11:42:38, Mahanta Jambigi wrote:
>
>
>On 29/08/25 8:28 pm, Dust Li wrote:
>> > 
>> > Fixes: 8ade200(net/smc: add v2 format of CLC decline message)
>> > 
>> > Signed-off-by: Mahanta Jambigi <mjambigi@...ux.ibm.com>
>> > Reference-ID: LTC214332
>> 
>> I think this is your internal ID ? It's better not to leave that
>> in the upstream patches.
>
>Oops, I missed to remove it. Sure, I'll remove it.
>
>> 
>> > Reviewed-by: Sidraya Jayagond <sidraya@...ux.ibm.com>
>> > Reviewed-by: Alexandra Winter <wintera@...ux.ibm.com>
>> > 
>> > ---
>> > net/smc/smc_clc.c | 2 --
>> > 1 file changed, 2 deletions(-)
>> > 
>> > diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c
>> > index 5a4db151fe95..08be56dfb3f2 100644
>> > --- a/net/smc/smc_clc.c
>> > +++ b/net/smc/smc_clc.c
>> > @@ -426,8 +426,6 @@ smc_clc_msg_decl_valid(struct smc_clc_msg_decline *dclc)
>> > {
>> > 	struct smc_clc_msg_hdr *hdr = &dclc->hdr;
>> > 
>> > -	if (hdr->typev1 != SMC_TYPE_R && hdr->typev1 != SMC_TYPE_D)
>> > -		return false;
>> 
>> Here it's checking the typev1 in smc_clc_msg_hdr, but your commit message
>> says it's validating the reserved bits:
>> 
>>    Currently SMC code is validating the reserved bits while parsing the incoming
>>    CLC decline message & when this validation fails, its treated as a protocol
>>    error.
>> 
>> Did I miss something ?
>
>If you refer to struct *smc_clc_msg_hdr* in smc_clc.h file, typev1 member
>represents bits 4 & 5 at offset 7. If we compare it with the CLC Decline
>message header, it represents one of the reserved(5-7 bits) at offset 7. You
>can refer to below link for reserved bits.
>
>https://datatracker.ietf.org/doc/html/rfc7609#page-105

Oh, I see, thanks! The patch looks good to me.


BTW, I checked the rfc7609 and SMCv2.1 spec:
https://www.ibm.com/support/pages/system/files/inline-files/IBM%20Shared%20Memory%20Communications%20Version%202.1_0.pdf

I think the name type1/type2 in smc_clc_msg_hdr is confusing, as it doesn't sync
with the spec for decline message.

Best regards,
Dust