linux-kernel - Re: [RFC net-next v3 5/6] net: phy: nxp-c45-tja11xx: add MACsec statistics

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Message-ID: <50617433-2c93-839a-445c-e0d11e95496e@oss.nxp.com>
Date:   Mon, 11 Sep 2023 18:04:30 +0300
From:   "Radu Pirea (OSS)" <radu-nicolae.pirea@....nxp.com>
To:     Sabrina Dubroca <sd@...asysnail.net>
Cc:     andrew@...n.ch, hkallweit1@...il.com, linux@...linux.org.uk,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, richardcochran@...il.com,
        sebastian.tobuschat@....com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC net-next v3 5/6] net: phy: nxp-c45-tja11xx: add MACsec
 statistics



On 11.09.2023 15:00, Sabrina Dubroca wrote:
> 2023-09-06, 19:01:33 +0300, Radu Pirea (NXP OSS) wrote:
>> +
>> +	nxp_c45_macsec_read(phydev, MACSEC_OPUS, &reg);
>> +	dev_stats->OutPktsUntagged = reg;
> 
> Can you read directly into OutPktsUntagged? It would make the code a
> little bit more readable.
> 
> It's a bit unfortunate that all those stats read turn into 2 (or 4 for
> the 64b counters) reads. If the HW's value can be incremented while
> we're reading it we'll see an inconsistent value :(
> 

The 32b reads are consistent. The inconsistency may appear when the 
lower half of a 64b register overflows.

>> +
>> +	nxp_c45_macsec_read(phydev, MACSEC_OOE1HS, &reg);
>> +	stats->OutOctetsEncrypted = (u64)reg << 32;
>> +	nxp_c45_macsec_read(phydev, MACSEC_OOE2HS, &reg);
>> +	stats->OutOctetsEncrypted |= reg;
> 
> Since you have a few 64b HW counters, I'd suggest a helper:
> 
> stats->OutOctetsEncrypted = nxp_c45_macsec_read64(phydev, MACSEC_OOE1HS, MACSEC_OOE2HS);
> 
> 
> Or (more consistent with the 32b reads):
> 
> nxp_c45_macsec_read64(phydev, MACSEC_OOE1HS, MACSEC_OOE2HS, &stats->OutOctetsEncrypted);
> 
> 

I will add two helper:
- nxp_c45_macsec_read32_64	- read 32bit counter into u64
- nxp_c45_macsec_read64		- read 64bit counter into u64

-- 
Radu P.