netdev - Re: [PATCH net v2] bnxt_en: update xdp_rxq

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Message-ID: <9f794505-9f9c-4d18-9b0f-c603ec0443c0@davidwei.uk>
Date: Sun, 21 Jul 2024 09:57:27 -0700
From: David Wei <dw@...idwei.uk>
To: Taehee Yoo <ap420073@...il.com>, davem@...emloft.net, kuba@...nel.org,
 pabeni@...hat.com, edumazet@...gle.com, michael.chan@...adcom.com,
 netdev@...r.kernel.org
Cc: somnath.kotur@...adcom.com, horms@...nel.org
Subject: Re: [PATCH net v2] bnxt_en: update xdp_rxq_info in queue restart
 logic

On 2024-07-20 22:35, Taehee Yoo wrote:
> When the netdev_rx_queue_restart() restarts queues, the bnxt_en driver
> updates(creates and deletes) a page_pool.
> But it doesn't update xdp_rxq_info, so the xdp_rxq_info is still
> connected to an old page_pool.
> So, bnxt_rx_ring_info->page_pool indicates a new page_pool, but
> bnxt_rx_ring_info->xdp_rxq is still connected to an old page_pool.
> 
> An old page_pool is no longer used so it is supposed to be
> deleted by page_pool_destroy() but it isn't.
> Because the xdp_rxq_info is holding the reference count for it and the
> xdp_rxq_info is not updated, an old page_pool will not be deleted in
> the queue restart logic.
> 
> Before restarting 1 queue:
> ./tools/net/ynl/samples/page-pool
> enp10s0f1np1[6] page pools: 4 (zombies: 0)
> 	refs: 8192 bytes: 33554432 (refs: 0 bytes: 0)
> 	recycling: 0.0% (alloc: 128:8048 recycle: 0:0)
> 
> After restarting 1 queue:
> ./tools/net/ynl/samples/page-pool
> enp10s0f1np1[6] page pools: 5 (zombies: 0)
> 	refs: 10240 bytes: 41943040 (refs: 0 bytes: 0)
> 	recycling: 20.0% (alloc: 160:10080 recycle: 1920:128)
> 
> Before restarting queues, an interface has 4 page_pools.
> After restarting one queue, an interface has 5 page_pools, but it
> should be 4, not 5.
> The reason is that queue restarting logic creates a new page_pool and
> an old page_pool is not deleted due to the absence of an update of
> xdp_rxq_info logic.
> 
> Fixes: 2d694c27d32e ("bnxt_en: implement netdev_queue_mgmt_ops")
> Signed-off-by: Taehee Yoo <ap420073@...il.com>
> ---
> 
> v2:
>  - Do not use memcpy in the bnxt_queue_start
>  - Call xdp_rxq_info_unreg() before page_pool_destroy() in the
>    bnxt_queue_mem_free().
> 
>  drivers/net/ethernet/broadcom/bnxt/bnxt.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> index bb3be33c1bbd..ffa74c26ee53 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> @@ -4052,6 +4052,7 @@ static void bnxt_reset_rx_ring_struct(struct bnxt *bp,
>  
>  	rxr->page_pool->p.napi = NULL;
>  	rxr->page_pool = NULL;
> +	memset(&rxr->xdp_rxq, 0, sizeof(struct xdp_rxq_info));
>  
>  	ring = &rxr->rx_ring_struct;
>  	rmem = &ring->ring_mem;
> @@ -15018,6 +15019,16 @@ static int bnxt_queue_mem_alloc(struct net_device *dev, void *qmem, int idx)
>  	if (rc)
>  		return rc;
>  
> +	rc = xdp_rxq_info_reg(&clone->xdp_rxq, bp->dev, idx, 0);
> +	if (rc < 0)
> +		goto err_page_pool_destroy;
> +
> +	rc = xdp_rxq_info_reg_mem_model(&clone->xdp_rxq,
> +					MEM_TYPE_PAGE_POOL,
> +					clone->page_pool);
> +	if (rc)
> +		goto err_rxq_info_unreg;
> +
>  	ring = &clone->rx_ring_struct;
>  	rc = bnxt_alloc_ring(bp, &ring->ring_mem);
>  	if (rc)
> @@ -15047,6 +15058,9 @@ static int bnxt_queue_mem_alloc(struct net_device *dev, void *qmem, int idx)
>  	bnxt_free_ring(bp, &clone->rx_agg_ring_struct.ring_mem);
>  err_free_rx_ring:
>  	bnxt_free_ring(bp, &clone->rx_ring_struct.ring_mem);
> +err_rxq_info_unreg:
> +	xdp_rxq_info_unreg(&clone->xdp_rxq);
> +err_page_pool_destroy:
>  	clone->page_pool->p.napi = NULL;
>  	page_pool_destroy(clone->page_pool);
>  	clone->page_pool = NULL;
> @@ -15062,6 +15076,8 @@ static void bnxt_queue_mem_free(struct net_device *dev, void *qmem)
>  	bnxt_free_one_rx_ring(bp, rxr);
>  	bnxt_free_one_rx_agg_ring(bp, rxr);
>  
> +	xdp_rxq_info_unreg(&rxr->xdp_rxq);
> +
>  	page_pool_destroy(rxr->page_pool);
>  	rxr->page_pool = NULL;
>  
> @@ -15145,6 +15161,7 @@ static int bnxt_queue_start(struct net_device *dev, void *qmem, int idx)
>  	rxr->rx_sw_agg_prod = clone->rx_sw_agg_prod;
>  	rxr->rx_next_cons = clone->rx_next_cons;
>  	rxr->page_pool = clone->page_pool;
> +	rxr->xdp_rxq = clone->xdp_rxq;
>  
>  	bnxt_copy_rx_ring(bp, rxr, clone);
>  

Thanks for addressing my comments. Checkpatch and make W=1 C=1 also
showed no errors.

Reviewed-by: David Wei <dw@...idwei.uk>