linux-kernel - Re: [PATCH v9 4/7] nfc: pn533: Split pn533 init & nfc

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Date:   Wed, 9 Oct 2019 17:40:23 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Lars Poeschel <poeschel@...onage.de>
Cc:     Jilayne Lovejoy <opensource@...ayne.com>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Allison Randal <allison@...utok.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Steve Winslow <swinslow@...il.com>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Johan Hovold <johan@...nel.org>,
        netdev@...r.kernel.org (open list:NFC SUBSYSTEM),
        linux-kernel@...r.kernel.org (open list),
        Claudiu Beznea <Claudiu.Beznea@...rochip.com>
Subject: Re: [PATCH v9 4/7] nfc: pn533: Split pn533 init & nfc_register

On Tue,  8 Oct 2019 16:05:41 +0200, Lars Poeschel wrote:
> There is a problem in the initialisation and setup of the pn533: It
> registers with nfc too early. It could happen, that it finished
> registering with nfc and someone starts using it. But setup of the pn533
> is not yet finished. Bad or at least unintended things could happen.
> So I split out nfc registering (and unregistering) to seperate functions
> that have to be called late in probe then.
> 
> Cc: Johan Hovold <johan@...nel.org>
> Cc: Claudiu Beznea <Claudiu.Beznea@...rochip.com>
> Signed-off-by: Lars Poeschel <poeschel@...onage.de>

> diff --git a/drivers/nfc/pn533/i2c.c b/drivers/nfc/pn533/i2c.c
> index 1abd40398a5a..e9e5a1ec8857 100644
> --- a/drivers/nfc/pn533/i2c.c
> +++ b/drivers/nfc/pn533/i2c.c
> @@ -193,12 +193,10 @@ static int pn533_i2c_probe(struct i2c_client *client,
>  	phy->i2c_dev = client;
>  	i2c_set_clientdata(client, phy);
>  
> -	priv = pn533_register_device(PN533_DEVICE_PN532,
> -				     PN533_NO_TYPE_B_PROTOCOLS,
> +	priv = pn53x_common_init(PN533_DEVICE_PN532,
>  				     PN533_PROTO_REQ_ACK_RESP,
>  				     phy, &i2c_phy_ops, NULL,
> -				     &phy->i2c_dev->dev,
> -				     &client->dev);
> +				     &phy->i2c_dev->dev);

nit: start of continuation lines should match the opening parenthesis,
     please run checkpatch and fix the style issue

>  	if (IS_ERR(priv)) {
>  		r = PTR_ERR(priv);
> @@ -220,13 +218,17 @@ static int pn533_i2c_probe(struct i2c_client *client,
>  	if (r)
>  		goto fn_setup_err;
>  
> -	return 0;
> +	r = pn53x_register_nfc(priv, PN533_NO_TYPE_B_PROTOCOLS, &client->dev);
> +	if (r)
> +		goto fn_setup_err;
> +
> +	return r;
>  
>  fn_setup_err:
>  	free_irq(client->irq, phy);
>  
>  irq_rqst_err:
> -	pn533_unregister_device(phy->priv);
> +	pn53x_common_clean(phy->priv);
>  
>  	return r;
>  }
> @@ -239,7 +241,8 @@ static int pn533_i2c_remove(struct i2c_client *client)
>  
>  	free_irq(client->irq, phy);
>  
> -	pn533_unregister_device(phy->priv);
> +	pn53x_unregister_nfc(phy->priv);
> +	pn53x_common_clean(phy->priv);
>  
>  	return 0;
>  }
> diff --git a/drivers/nfc/pn533/pn533.c b/drivers/nfc/pn533/pn533.c
> index 64836c727aee..e5d5e4c83a04 100644
> --- a/drivers/nfc/pn533/pn533.c
> +++ b/drivers/nfc/pn533/pn533.c
> @@ -2590,14 +2590,12 @@ int pn533_finalize_setup(struct pn533 *dev)
>  }
>  EXPORT_SYMBOL_GPL(pn533_finalize_setup);
>  
> -struct pn533 *pn533_register_device(u32 device_type,
> -				u32 protocols,
> +struct pn533 *pn53x_common_init(u32 device_type,
>  				enum pn533_protocol_type protocol_type,
>  				void *phy,
>  				struct pn533_phy_ops *phy_ops,
>  				struct pn533_frame_ops *fops,
> -				struct device *dev,
> -				struct device *parent)
> +				struct device *dev)
>  {
>  	struct pn533 *priv;
>  	int rc = -ENOMEM;
> @@ -2638,43 +2636,18 @@ struct pn533 *pn533_register_device(u32 device_type,
>  	skb_queue_head_init(&priv->fragment_skb);
>  
>  	INIT_LIST_HEAD(&priv->cmd_queue);
> -
> -	priv->nfc_dev = nfc_allocate_device(&pn533_nfc_ops, protocols,
> -					   priv->ops->tx_header_len +
> -					   PN533_CMD_DATAEXCH_HEAD_LEN,
> -					   priv->ops->tx_tail_len);
> -	if (!priv->nfc_dev) {
> -		rc = -ENOMEM;
> -		goto destroy_wq;
> -	}
> -
> -	nfc_set_parent_dev(priv->nfc_dev, parent);
> -	nfc_set_drvdata(priv->nfc_dev, priv);
> -
> -	rc = nfc_register_device(priv->nfc_dev);
> -	if (rc)
> -		goto free_nfc_dev;

Aren't you moving too much out of here? Looking at commit 32ecc75ded72
("NFC: pn533: change order operations in dev registation") it seems like
IRQ handler may want to access the data structures, do this change not
reintroduce the problem?

>  	return priv;
>  
> -free_nfc_dev:
> -	nfc_free_device(priv->nfc_dev);
> -
> -destroy_wq:
> -	destroy_workqueue(priv->wq);
>  error:
>  	kfree(priv);
>  	return ERR_PTR(rc);
>  }
> -EXPORT_SYMBOL_GPL(pn533_register_device);
> +EXPORT_SYMBOL_GPL(pn53x_common_init);
>  
> -void pn533_unregister_device(struct pn533 *priv)
> +void pn53x_common_clean(struct pn533 *priv)
>  {
>  	struct pn533_cmd *cmd, *n;
>  
> -	nfc_unregister_device(priv->nfc_dev);
> -	nfc_free_device(priv->nfc_dev);
> -
>  	flush_delayed_work(&priv->poll_work);
>  	destroy_workqueue(priv->wq);
>