Re: [PATCH net-next v2 2/2] net: xilinx: axienet: Add statistics support

From: Sean Anderson
Date: Mon Aug 12 2024 - 16:25:34 EST


On 8/12/24 16:22, Andrew Lunn wrote:
>> static int __axienet_device_reset(struct axienet_local *lp)
>> {
>> u32 value;
>> int ret;
>>
>> + /* Save statistics counters in case they will be reset */
>> + guard(mutex)(&lp->stats_lock);
>> + if (lp->features & XAE_FEATURE_STATS)
>> + axienet_stats_update(lp, true);
>
> My understanding of guard() is that the mutex is held until the
> function completes. That is much longer than you need. A
> scoped_guard() would be better here, and it makes it clear when the
> mutex will be released.

We have to hold it until...

>> +
>> /* Reset Axi DMA. This would reset Axi Ethernet core as well. The reset
>> * process of Axi DMA takes a while to complete as all pending
>> * commands/transfers will be flushed or completed during this
>> @@ -551,6 +595,23 @@ static int __axienet_device_reset(struct axienet_local *lp)
>> return ret;
>> }
>>
>> + /* Update statistics counters with new values */
>> + if (lp->features & XAE_FEATURE_STATS) {
>> + enum temac_stat stat;
>> +
>> + write_seqcount_begin(&lp->hw_stats_seqcount);
>> + lp->reset_in_progress = false;
>> + for (stat = 0; stat < STAT_COUNT; stat++) {
>> + u32 counter =
>> + axienet_ior(lp, XAE_STATS_OFFSET + stat * 8);
>> +
>> + lp->hw_stat_base[stat] +=
>> + lp->hw_last_counter[stat] - counter;
>> + lp->hw_last_counter[stat] = counter;
>> + }
>> + write_seqcount_end(&lp->hw_stats_seqcount);

...here

Which is effectively the whole function. The main reason why I used guard() was to
simplify the error return cases.

--Sean

>> + }
>> +
>> return 0;
>> }
>>
>
> Andrew