netdev - Re: [PATCH net-next v1 2/3] bnxt_en: stop packet flow during bnxt_queue

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Message-ID: <6a6b3aff-c00c-481b-9a83-7dfc324d6b02@davidwei.uk>
Date: Wed, 31 Jul 2024 12:35:11 +0100
From: David Wei <dw@...idwei.uk>
To: Wojciech Drewek <wojciech.drewek@...el.com>, netdev@...r.kernel.org
Cc: Jakub Kicinski <kuba@...nel.org>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Paolo Abeni <pabeni@...hat.com>, Michael Chan <michael.chan@...adcom.com>
Subject: Re: [PATCH net-next v1 2/3] bnxt_en: stop packet flow during
 bnxt_queue_stop/start

On 2024-07-30 11:31, Wojciech Drewek wrote:
> 
> 
> On 29.07.2024 22:54, David Wei wrote:
>> Calling napi_stop/start during bnxt_queue_stop/start isn't enough. The
>> current implementation when resetting a queue while packets are flowing
>> puts the queue into an inconsistent state.
>>
>> There needs to be some synchronisation with the FW. Add calls to
>> bnxt_hwrm_vnic_update() to set the MRU for both the default and ntuple
>> vnic during queue start/stop. When the MRU is set to 0, flow is stopped.
>> Each Rx queue belongs to either the default or the ntuple vnic.
>>
>> Co-Developed-by: Somnath Kotur <somnath.kotur@...adcom.com>
>> Signed-off-by: Somnath Kotur <somnath.kotur@...adcom.com>
>> Signed-off-by: David Wei <dw@...idwei.uk>
>> ---
>>  drivers/net/ethernet/broadcom/bnxt/bnxt.c | 22 ++++++++++++++++++----
>>  1 file changed, 18 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
>> index 8822d7a17fbf..ce60c9322fe6 100644
>> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
>> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
>> @@ -15172,7 +15172,8 @@ static int bnxt_queue_start(struct net_device *dev, void *qmem, int idx)
>>  	struct bnxt *bp = netdev_priv(dev);
>>  	struct bnxt_rx_ring_info *rxr, *clone;
>>  	struct bnxt_cp_ring_info *cpr;
>> -	int rc;
>> +	struct bnxt_vnic_info *vnic;
>> +	int i, rc;
>>  
>>  	rxr = &bp->rx_ring[idx];
>>  	clone = qmem;
>> @@ -15197,11 +15198,16 @@ static int bnxt_queue_start(struct net_device *dev, void *qmem, int idx)
>>  	if (bp->flags & BNXT_FLAG_AGG_RINGS)
>>  		bnxt_db_write(bp, &rxr->rx_agg_db, rxr->rx_agg_prod);
>>  
>> -	napi_enable(&rxr->bnapi->napi);
> 
> I get it that napi_{enable|enable} isn't enough but why removing it?
> Without it, RX will not work, the poll method won't be called or am I missing something?

>From my testing removing napi_enable/disable() is needed for reset to
work on a queue that has traffic flowing.

Let me edit the commit message to make this bit clearer. Thanks.

> 
>> -
>>  	cpr = &rxr->bnapi->cp_ring;
>>  	cpr->sw_stats->rx.rx_resets++;
>>  
>> +	for (i = 0; i <= BNXT_VNIC_NTUPLE; i++) {
>> +		vnic = &bp->vnic_info[i];
>> +		vnic->mru = bp->dev->mtu + ETH_HLEN + VLAN_HLEN;
>> +		bnxt_hwrm_vnic_update(bp, vnic,
>> +				      VNIC_UPDATE_REQ_ENABLES_MRU_VALID);
>> +	}
>> +
>>  	return 0;
>>  
>>  err_free_hwrm_rx_ring:
>> @@ -15213,9 +15219,17 @@ static int bnxt_queue_stop(struct net_device *dev, void *qmem, int idx)
>>  {
>>  	struct bnxt *bp = netdev_priv(dev);
>>  	struct bnxt_rx_ring_info *rxr;
>> +	struct bnxt_vnic_info *vnic;
>> +	int i;
>> +
>> +	for (i = 0; i <= BNXT_VNIC_NTUPLE; i++) {
>> +		vnic = &bp->vnic_info[i];
>> +		vnic->mru = 0;
>> +		bnxt_hwrm_vnic_update(bp, vnic,
>> +				      VNIC_UPDATE_REQ_ENABLES_MRU_VALID);
>> +	}
>>  
>>  	rxr = &bp->rx_ring[idx];
>> -	napi_disable(&rxr->bnapi->napi);
>>  	bnxt_hwrm_rx_ring_free(bp, rxr, false);
>>  	bnxt_hwrm_rx_agg_ring_free(bp, rxr, false);
>>  	rxr->rx_next_cons = 0;