netdev - Re: [PATCH v5 4/5] net: rnpgbe: Add basic mbx

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Message-ID: <39262c11-b14f-462f-b9c0-4e7bd1f32f0d@lunn.ch>
Date: Wed, 20 Aug 2025 22:37:01 +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,
	netdev@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 4/5] net: rnpgbe: Add basic mbx_fw support

> +static int mucse_mbx_fw_post_req(struct mucse_hw *hw,
> +				 struct mbx_fw_cmd_req *req,
> +				 struct mbx_req_cookie *cookie)
> +{
> +	int len = le16_to_cpu(req->datalen);
> +	int err;
> +
> +	cookie->errcode = 0;
> +	cookie->done = 0;
> +	init_waitqueue_head(&cookie->wait);
> +	err = mutex_lock_interruptible(&hw->mbx.lock);
> +	if (err)
> +		return err;
> +	err = mucse_write_mbx(hw, (u32 *)req, len);
> +	if (err)
> +		goto out;
> +	err = wait_event_timeout(cookie->wait,
> +				 cookie->done == 1,
> +				 cookie->timeout_jiffies);
> +
> +	if (!err)
> +		err = -ETIMEDOUT;
> +	else
> +		err = 0;
> +	if (!err && cookie->errcode)
> +		err = cookie->errcode;
> +out:
> +	mutex_unlock(&hw->mbx.lock);
> +	return err;

What is your design with respect to mutex_lock_interruptible() and
then calling wait_event_timeout() which will ignore signals?

Is your intention that you can always ^C the driver, and it will clean
up whatever it was doing and return -EINTR? Such unwinding can be
tricky and needs careful review. Before i do that, i just want to make
sure this is your intention, and you yourself have carefully reviewed
the code.

   Andrew