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Date: Thu, 9 Jan 2025 16:14:00 +0000
From: Simon Horman <horms@kernel.org>
To: Suman Ghosh <sumang@marvell.com>
Cc: sgoutham@marvell.com, gakula@marvell.com, sbhatta@marvell.com,
	hkelam@marvell.com, davem@davemloft.net, edumazet@google.com,
	kuba@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, lcherian@marvell.com,
	jerinj@marvell.com, john.fastabend@gmail.com, bbhushan2@marvell.com,
	hawk@kernel.org, andrew+netdev@lunn.ch, ast@kernel.org,
	daniel@iogearbox.net, bpf@vger.kernel.org
Subject: Re: [net-next PATCH v2 3/6] octeontx2-pf: Add AF_XDP zero copy
 support for rx side
Message-ID: <20250109161400.GK7706@kernel.org>
References: <20250108183329.2207738-1-sumang@marvell.com>
 <20250108183329.2207738-4-sumang@marvell.com>
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In-Reply-To: <20250108183329.2207738-4-sumang@marvell.com>

On Thu, Jan 09, 2025 at 12:03:26AM +0530, Suman Ghosh wrote:
> This patch adds support to AF_XDP zero copy for CN10K.
> This patch specifically adds receive side support. In this approach once
> a xdp program with zero copy support on a specific rx queue is enabled,
> then that receive quse is disabled/detached from the existing kernel
> queue and re-assigned to the umem memory.
> 
> Signed-off-by: Suman Ghosh <sumang@marvell.com>

...

> diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c

...

> @@ -572,20 +575,31 @@ int otx2_napi_handler(struct napi_struct *napi, int budget)
>  		if (pfvf->flags & OTX2_FLAG_ADPTV_INT_COAL_ENABLED)
>  			otx2_adjust_adaptive_coalese(pfvf, cq_poll);
>  
> +		if (likely(cq))
> +			pool = &pfvf->qset.pool[cq->cq_idx];
> +

Hi Suman,

FWIIW, Smatch is still concerned that cq may be used uninitialised here.

...

> @@ -1429,13 +1447,24 @@ static bool otx2_xdp_rcv_pkt_handler(struct otx2_nic *pfvf,
>  	unsigned char *hard_start;
>  	struct otx2_pool *pool;
>  	int qidx = cq->cq_idx;
> -	struct xdp_buff xdp;
> +	struct xdp_buff xdp, *xsk_buff = NULL;
>  	struct page *page;
>  	u64 iova, pa;
>  	u32 act;
>  	int err;

Please consider preserving reverse xmas tree order - longest line to
shortest - for local variable declarations.

...