linux-kernel - Re: [PATCH net-next v10 3/5] net: rnpgbe: Add basic mbx ops support

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Message-ID: <659df824-7509-4ffe-949b-187d7d44f69f@lunn.ch>
Date: Thu, 4 Sep 2025 00:24:17 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Dong Yibo <dong100@...se.com>
Cc: andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
	kuba@...nel.org, pabeni@...hat.com, horms@...nel.org,
	corbet@....net, gur.stavi@...wei.com, maddy@...ux.ibm.com,
	mpe@...erman.id.au, danishanwar@...com, lee@...ger.us,
	gongfan1@...wei.com, lorenzo@...nel.org, geert+renesas@...der.be,
	Parthiban.Veerasooran@...rochip.com, lukas.bulwahn@...hat.com,
	alexanderduyck@...com, richardcochran@...il.com, kees@...nel.org,
	gustavoars@...nel.org, rdunlap@...radead.org,
	vadim.fedorenko@...ux.dev, netdev@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: Re: [PATCH net-next v10 3/5] net: rnpgbe: Add basic mbx ops support

>  struct mucse_mbx_info {
> +	struct mucse_mbx_stats stats;
> +	u32 timeout;
> +	u32 usec_delay;
> +	u16 size;
> +	u16 fw_req;
> +	u16 fw_ack;
> +	/* lock for only one use mbx */
> +	struct mutex lock;
>  	/* fw <--> pf mbx */
>  	u32 fw_pf_shm_base;
>  	u32 pf2fw_mbox_ctrl;

> +/**
> + * mucse_obtain_mbx_lock_pf - Obtain mailbox lock
> + * @hw: pointer to the HW structure
> + *
> + * This function maybe used in an irq handler.
> + *
> + * Return: 0 if we obtained the mailbox lock or else -EIO
> + **/
> +static int mucse_obtain_mbx_lock_pf(struct mucse_hw *hw)
> +{
> +	struct mucse_mbx_info *mbx = &hw->mbx;
> +	int try_cnt = 5000;
> +	u32 reg;
> +
> +	reg = PF2FW_MBOX_CTRL(mbx);
> +	while (try_cnt-- > 0) {
> +		mbx_ctrl_wr32(mbx, reg, MBOX_PF_HOLD);
> +		/* force write back before check */
> +		wmb();
> +		if (mbx_ctrl_rd32(mbx, reg) & MBOX_PF_HOLD)
> +			return 0;
> +		udelay(100);
> +	}
> +	return -EIO;
> +}

If there is a function which obtains a lock, there is normally a
function which releases a lock. But i don't see it.

> +void mucse_init_mbx_params_pf(struct mucse_hw *hw)
> +{
> +	struct mucse_mbx_info *mbx = &hw->mbx;
> +
> +	mbx->usec_delay = 100;
> +	mbx->timeout = (4 * USEC_PER_SEC) / mbx->usec_delay;
> +	mbx->stats.msgs_tx = 0;
> +	mbx->stats.msgs_rx = 0;
> +	mbx->stats.reqs = 0;
> +	mbx->stats.acks = 0;
> +	mbx->size = MUCSE_MAILBOX_BYTES;
> +	mutex_init(&mbx->lock);

And this mutex never seems to be used anywhere. What is it supposed to
be protecting?

    Andrew

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pw-bot: cr