netdev - Re: [PATCH net-next v1 3/3] bnxt_en: implement netdev_queue_mgmt

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Date: Mon, 17 Jun 2024 21:36:49 -0700
From: David Wei <dw@...idwei.uk>
To: Simon Horman <horms@...nel.org>
Cc: Michael Chan <michael.chan@...adcom.com>,
 Andy Gospodarek <andrew.gospodarek@...adcom.com>,
 Adrian Alvarado <adrian.alvarado@...adcom.com>,
 Somnath Kotur <somnath.kotur@...adcom.com>, netdev@...r.kernel.org,
 Pavel Begunkov <asml.silence@...il.com>, Jakub Kicinski <kuba@...nel.org>,
 David Ahern <dsahern@...nel.org>, "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH net-next v1 3/3] bnxt_en: implement netdev_queue_mgmt_ops

On 2024-06-14 13:07, Simon Horman wrote:
> On Mon, Jun 10, 2024 at 07:33:24PM -0700, David Wei wrote:
>> Implement netdev_queue_mgmt_ops for bnxt added in [1].
>>
>> Two bnxt_rx_ring_info structs are allocated to hold the new/old queue
>> memory. Queue memory is copied from/to the main bp->rx_ring[idx]
>> bnxt_rx_ring_info.
>>
>> Queue memory is pre-allocated in bnxt_queue_mem_alloc() into a clone,
>> and then copied into bp->rx_ring[idx] in bnxt_queue_mem_start().
>>
>> Similarly, when bp->rx_ring[idx] is stopped its queue memory is copied
>> into a clone, and then freed later in bnxt_queue_mem_free().
>>
>> I tested this patchset with netdev_rx_queue_restart(), including
>> inducing errors in all places that returns an error code. In all cases,
>> the queue is left in a good working state.
>>
>> Rx queues are stopped/started using bnxt_hwrm_vnic_update(), which only
>> affects queues that are not in the default RSS context. This is
>> different to the GVE that also implemented the queue API recently where
>> arbitrary Rx queues can be stopped. Due to this limitation, all ndos
>> returns EOPNOTSUPP if the queue is in the default RSS context.
>>
>> Thanks to Somnath for helping me with using bnxt_hwrm_vnic_update() to
>> stop/start an Rx queue. With their permission I've added them as
>> Acked-by.
>>
>> [1]: https://lore.kernel.org/netdev/20240501232549.1327174-2-shailend@google.com/
>>
>> Acked-by: Somnath Kotur <somnath.kotur@...adcom.com>
>> Signed-off-by: David Wei <dw@...idwei.uk>
>> ---
>>  drivers/net/ethernet/broadcom/bnxt/bnxt.c | 307 ++++++++++++++++++++++
>>  1 file changed, 307 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> 
> ...
> 
>> +static void bnxt_queue_mem_free(struct net_device *dev, void *qmem)
>> +{
>> +	struct bnxt_rx_ring_info *rxr = qmem;
>> +	struct bnxt *bp = netdev_priv(dev);
>> +	struct bnxt_ring_struct *ring;
>> +
>> +	if (bnxt_get_max_rss_ring(bp) >= idx)
>> +		return -EOPNOTSUPP;
> 
> Hi David,
> 
> I guess there was some last minute refactoring and these sloped through the
> cracks. The two lines above seem a bit out of place here.
> 
> * idx doesn't exist in this context
> * The return type of this function is void

Hi Simon, thanks, you were absolutely right and these slipped through at
the end. Will be fixed in the next version.

> 
>> +
>> +	bnxt_free_one_rx_ring(bp, rxr);
>> +	bnxt_free_one_rx_agg_ring(bp, rxr);
>> +
>> +	/* At this point, this NAPI instance has another page pool associated
>> +	 * with it. Disconnect here before freeing the old page pool to avoid
>> +	 * warnings.
>> +	 */
>> +	rxr->page_pool->p.napi = NULL;
>> +	page_pool_destroy(rxr->page_pool);
>> +	rxr->page_pool = NULL;
>> +
>> +	ring = &rxr->rx_ring_struct;
>> +	bnxt_free_ring(bp, &ring->ring_mem);
>> +
>> +	ring = &rxr->rx_agg_ring_struct;
>> +	bnxt_free_ring(bp, &ring->ring_mem);
>> +
>> +	kfree(rxr->rx_agg_bmap);
>> +	rxr->rx_agg_bmap = NULL;
>> +}
> 
> ...