Date:   Fri, 10 Mar 2023 12:14:08 +0800
From:   "Ye, Xiang" <xiang.ye@...el.com>
To:     Oliver Neukum <oneukum@...e.com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Matthias Kaehlcke <mka@...omium.org>,
        Lee Jones <lee@...nel.org>, Wolfram Sang <wsa@...nel.org>,
        Tyrone Ting <kfting@...oton.com>,
        Mark Brown <broonie@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        <linux-usb@...r.kernel.org>, <linux-i2c@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-spi@...r.kernel.org>,
        <linux-gpio@...r.kernel.org>, <srinivas.pandruvada@...el.com>,
        <heikki.krogerus@...ux.intel.com>,
        <andriy.shevchenko@...ux.intel.com>,
        <sakari.ailus@...ux.intel.com>, <zhifeng.wang@...el.com>,
        <wentong.wu@...el.com>, <lixu.zhang@...el.com>
Subject: Re: [PATCH v4 1/5] mfd: Add support for Intel LJCA device

Hi Oliver,

Thanks for your review.
On Thu, Mar 09, 2023 at 01:53:28PM +0100, Oliver Neukum wrote:
> 
> 
> On 09.03.23 08:10, Ye Xiang wrote:
> 
> > +static int ljca_stub_write(struct ljca_stub *stub, u8 cmd, const void *obuf, unsigned int obuf_len,
> > +			   void *ibuf, unsigned int *ibuf_len, bool wait_ack, unsigned long timeout)
> 
> Why do you make ibuf_len a pointer?
Because ibuf_len is also used as output of this function here.
It stores the actual length of ibuf receive from LJCA device.
> 
> > +{
> > +	struct ljca_dev *dev = usb_get_intfdata(stub->intf);
> > +	u8 flags = LJCA_CMPL_FLAG;
> > +	struct ljca_msg *header;
> > +	unsigned int msg_len = sizeof(*header) + obuf_len;
> > +	int actual;
> > +	int ret;
> > +
> > +	if (msg_len > LJCA_MAX_PACKET_SIZE)
> > +		return -EINVAL;
> > +
> > +	if (wait_ack)
> > +		flags |= LJCA_ACK_FLAG;
> > +
> > +	header = kmalloc(msg_len, GFP_KERNEL);
> > +	if (!header)
> > +		return -ENOMEM;
> > +
> > +	header->type = stub->type;
> > +	header->cmd = cmd;
> > +	header->flags = flags;
> > +	header->len = obuf_len;
> > +
> > +	if (obuf)
> > +		memcpy(header->data, obuf, obuf_len);
> > +
> > +	dev_dbg(&dev->intf->dev, "send: type:%d cmd:%d flags:%d len:%d\n", header->type,
> > +		header->cmd, header->flags, header->len);
> > +
> > +	usb_autopm_get_interface(dev->intf);
> > +	if (!dev->started) {
> 
> Memory leak in error case. You must free header.
Good catch. Thanks. Will address it.
> 
> > +		ret = -ENODEV;
> > +		goto error_put;
> > +	}
> > +
> > +	mutex_lock(&dev->mutex);
> > +	stub->cur_cmd = cmd;
> > +	stub->ipacket.ibuf = ibuf;
> > +	stub->ipacket.ibuf_len = ibuf_len;
> > +	stub->acked = false;
> > +	ret = usb_bulk_msg(dev->udev, usb_sndbulkpipe(dev->udev, dev->out_ep), header, msg_len,
> > +			   &actual, LJCA_USB_WRITE_TIMEOUT_MS);
> > +	kfree(header);
> > +	if (ret) {
> > +		dev_err(&dev->intf->dev, "bridge write failed ret:%d\n", ret);
> > +		goto error_unlock;
> > +	}
> > +
> > +	if (actual != msg_len) {
> > +		dev_err(&dev->intf->dev, "bridge write length mismatch (%d vs %d)\n", msg_len,
> > +			actual);
> > +		ret = -EINVAL;
> > +		goto error_unlock;
> > +	}
> > +
> > +	if (wait_ack) {
> > +		ret = wait_event_timeout(dev->ack_wq, stub->acked, msecs_to_jiffies(timeout));
> > +		if (!ret) {
> > +			dev_err(&dev->intf->dev, "acked wait timeout\n");
> > +			ret = -ETIMEDOUT;
> 
> If that triggers, you may have a pending URB.
> You must kill it.
which URB? I guess what you mean is dev->in_urb?
But the in_urb should always be up to waiting for message from firmware,
even through this timeout happen.

> 
> > +			goto error_unlock;
> > +		}
> > +	}
> > +
> > +	stub->ipacket.ibuf = NULL;
> > +	stub->ipacket.ibuf_len = NULL;
> > +	ret = 0;
> > +error_unlock:
> > +	mutex_unlock(&dev->mutex);
> > +error_put:
> > +	usb_autopm_put_interface(dev->intf);
> > +	return ret;
> > +}
> 
> 
> > +static int ljca_i2c_stub_init(struct ljca_dev *dev, struct ljca_i2c_descriptor *desc)
> > +{
> > +	struct ljca_i2c_info *i2c_info;
> > +	struct ljca_stub *stub;
> > +	int ret;
> > +	int i;
> > +
> > +	stub = ljca_stub_alloc(dev, LJCA_I2C_STUB, size_mul(desc->num, sizeof(*i2c_info)));
> > +	if (IS_ERR(stub))
> > +		return PTR_ERR(stub);
> > +
> > +	i2c_info = ljca_priv(stub);
> > +
> > +	for (i = 0; i < desc->num; i++) {
> > +		struct mfd_cell cell = {};
> > +
> > +		i2c_info[i].ljca = &stub->ljca;
> > +		i2c_info[i].id = desc->info[i].id;
> > +		i2c_info[i].capacity = desc->info[i].capacity;
> > +		i2c_info[i].intr_pin = desc->info[i].intr_pin;
> > +
> > +		cell.name = "ljca-i2c";
> > +		cell.platform_data = &i2c_info[i];
> > +		cell.pdata_size = sizeof(i2c_info[i]);
> > +
> > +		if (i < ARRAY_SIZE(ljca_acpi_match_i2cs))
> > +			cell.acpi_match = &ljca_acpi_match_i2cs[i];
> > +
> > +		ret = ljca_add_mfd_cell(dev, &cell);
> > +		if (ret)
> > +			return ret;
> 
> What happens to stub in the error case?
ljca_add_mfd_cell only failed when krealloc_array failing. When
ljca_add_mfd_cell fails, the related stub just be left alone here.

Maybe I should free the stub here when fails? what is your advice?
> 
> > +	}
> > +
> > +	return 0;
> > +}
> 
> 
> > +
> > +static void ljca_disconnect(struct usb_interface *intf)
> > +{
> > +	struct ljca_dev *dev = usb_get_intfdata(intf);
> > +
> > +	ljca_stop(dev);
> 
> What prevents restarting the device here?
Why need to restart the device here?
The ljca_disconnect function should be called when the LJCA device is
unplugged.
> 
> > +	mfd_remove_devices(&intf->dev);
> > +	ljca_stub_cleanup(dev);
> > +	ljca_delete(dev);
> > +}
> > +
> > +static int ljca_suspend(struct usb_interface *intf, pm_message_t message)
> > +{
> > +	struct ljca_dev *dev = usb_get_intfdata(intf);
> > +
> > +	ljca_stop(dev);
> > +	return 0;
> > +}
> > +
> > +static int ljca_resume(struct usb_interface *intf)
> > +{
> > +	struct ljca_dev *dev = usb_get_intfdata(intf);
> > +
> > +	return ljca_start(dev);
> 
> So here you report errors, but at the same time you set "started"
> even if errors occur.
Thanks, Got it. Will address it on next version.

--
Thanks
Ye Xiang

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