netdev - Re: [PATCH net-next] eea: Add basic driver framework for Alibaba Elastic Ethernet Adaptor

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Message-ID: <dc023486-5491-4795-8b07-4808e44c8ebb@linux.dev>
Date: Fri, 11 Jul 2025 12:45:41 +0100
From: Vadim Fedorenko <vadim.fedorenko@...ux.dev>
To: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, netdev@...r.kernel.org
Cc: Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Wen Gu <guwen@...ux.alibaba.com>, Philo Lu <lulie@...ux.alibaba.com>,
 Lorenzo Bianconi <lorenzo@...nel.org>,
 Lukas Bulwahn <lukas.bulwahn@...hat.com>,
 Parthiban Veerasooran <Parthiban.Veerasooran@...rochip.com>,
 Geert Uytterhoeven <geert+renesas@...der.be>,
 Alexander Duyck <alexanderduyck@...com>, Dust Li <dust.li@...ux.alibaba.com>
Subject: Re: [PATCH net-next] eea: Add basic driver framework for Alibaba
 Elastic Ethernet Adaptor

On 10/07/2025 12:28, Xuan Zhuo wrote:
> +/* notify */
> +bool ering_kick(struct ering *ering)
> +{
> +	union {
> +		u64 data;
> +		struct db db;
> +	} val;
> +
> +	val.db.kick_flags = EEA_IDX_PRESENT;
> +	val.db.idx = cpu_to_le16(ering->sq.hw_idx);
> +
> +	writeq(val.data, (void __iomem *)ering->db);
> +
> +	return true;
> +}
> +

[...]

> +static inline bool ering_irq_unactive(struct ering *ering)
> +{
> +	union {
> +		u64 data;
> +		struct db db;
> +	} val;
> +
> +	if (ering->mask == EEA_IRQ_MASK)
> +		return true;
> +
> +	ering->mask = EEA_IRQ_MASK;
> +
> +	val.db.kick_flags = EEA_IRQ_MASK;
> +
> +	writeq(val.data, (void __iomem *)ering->db);
> +
> +	return true;
> +}
> +
> +static inline bool ering_irq_active(struct ering *ering, struct ering *tx_ering)
> +{
> +	union {
> +		u64 data;
> +		struct db db;
> +	} val;
> +
> +	if (ering->mask == EEA_IRQ_UNMASK)
> +		return true;
> +
> +	ering->mask = EEA_IRQ_UNMASK;
> +
> +	val.db.kick_flags = EEA_IRQ_UNMASK;
> +
> +	val.db.tx_cq_head = cpu_to_le16(tx_ering->cq.hw_idx);
> +	val.db.rx_cq_head = cpu_to_le16(ering->cq.hw_idx);
> +
> +	writeq(val.data, (void __iomem *)ering->db);
> +
> +	return true;
> +}

in addition to Andrew's comments, these union { ... } val will have
partial garbage values, which will later be directly sent to FW. I
believe it may cause some troubles and it's better to initialize val
before actually use it.