RE: Patch ' usb: gadget: cdc2: convert to new interface of f_ecm' applied to my tree

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On Wednesday, June 12, 2013 5:17 PM Felipe Balbi wrote:
> Hi,
> 
> This is a note to let you know that the patch:
> 
> 	    usb: gadget: cdc2: convert to new interface of f_ecm
> 
> has been applied to my tree and can be found at:
> 
> 	http://bit.ly/172DRHC
> 
> a snapshot of the tree can be downloaded from:
> 
> 	http://bit.ly/11zcltc
> 
> Note that it might take up to 20 minutes for kernel.org to synchronize the
> changes to its frontend servers.
> 
> If you have any concerns, please let me know by replying to this mail.
> 

Hi Felipe,

During testing the gadgets I discovered a strange behavior of the cdc.ko
gadget. It turns out that what has been applied to your tree is different
from what I have submitted.

The main difference (which I suppose causes trouble) is that
usb_get_function_instance() is called from cdc_bind()
(which is good and intended) and then again its invocation is repeated
in cdc_do_config (which is bad).

Originally Sebastian's conversion of acm to new function interface did
usb_get_function_instance() only in one place, cdc_do_config().
Later on I discovered that the code is much cleaner if the following
convention is obeyed: usb_get_function_instance() is called only from
xxx_bind(), while usb_get_function() is called only from xxx_do_config().

The patch I submitted:

http://www.spinics.net/lists/linux-usb/msg86326.html

indeed follows the said convention. However, what has been applied does not.

I reverted the patch in question and applied it again after making necessary
corrections so that it is consistent with what I have submitted. After
squashing the two a simple patch results and I'm sending it - in a separate
mail.

Please see below for what looks bad to me:


> From a38a275030086d95306555e544fc7c0e65ccd00e Mon Sep 17 00:00:00 2001
> From: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
> Date: Thu, 23 May 2013 10:32:04 +0200
> Subject: [PATCH] usb: gadget: cdc2: convert to new interface of f_ecm
> 
> f_ecm has been converted to new configfs infrastructure, fixing cdc2
> gadget driver.
> 
> [ balbi@xxxxxx : fixed a bunch of errors when adding ECM function ]
> 
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> Signed-off-by: Felipe Balbi <balbi@xxxxxx>
> ---
>  drivers/usb/gadget/Kconfig |  1 +
>  drivers/usb/gadget/cdc2.c  | 86 +++++++++++++++++++++++++++++++----------
> -----
>  2 files changed, 60 insertions(+), 27 deletions(-)
> 

<snip>

> diff --git a/drivers/usb/gadget/cdc2.c b/drivers/usb/gadget/cdc2.c index
> ceedaf7..5a5acf2 100644
> --- a/drivers/usb/gadget/cdc2.c
> +++ b/drivers/usb/gadget/cdc2.c
> @@ -15,6 +15,7 @@
> 

<snip>

>  /*
>   * We _always_ have both CDC ECM and CDC ACM functions.
>   */
> @@ -122,13 +113,27 @@ static int __init cdc_do_config(struct
> usb_configuration *c)
>  		c->bmAttributes |= USB_CONFIG_ATT_WAKEUP;
>  	}
> 
> -	status = ecm_bind_config(c, host_mac, the_dev);
> -	if (status < 0)
> -		return status;
> +	fi_ecm = usb_get_function_instance("ecm");

When control reaches this point the usb_get_function_instance("ecm")
has already been called in cdc_bind

> +	if (IS_ERR(fi_ecm)) {
> +		status = PTR_ERR(fi_ecm);
> +		goto err_func_ecm;
> +	}
> +
> +	f_ecm = usb_get_function(fi_ecm);
> +	if (IS_ERR(f_ecm)) {
> +		status = PTR_ERR(f_ecm);
> +		goto err_get_ecm;
> +	}
> +
> +	status = usb_add_function(c, f_ecm);
> +	if (status)
> +		goto err_add_ecm;
> 
>  	fi_serial = usb_get_function_instance("acm");

When control reaches this point the usb_get_function_instance("acm")
has already been called in cdc_bind

> -	if (IS_ERR(fi_serial))
> -		return PTR_ERR(fi_serial);
> +	if (IS_ERR(fi_serial)) {
> +		status = PTR_ERR(fi_serial);
> +		goto err_get_acm;
> +	}
> 
>  	f_acm = usb_get_function(fi_serial);
>  	if (IS_ERR(f_acm)) {
> @@ -138,12 +143,21 @@ static int __init cdc_do_config(struct
> usb_configuration *c)
> 
>  	status = usb_add_function(c, f_acm);
>  	if (status)
> -		goto err_conf;
> +		goto err_add_acm;
> +
>  	return 0;
> -err_conf:
> +
> +err_add_acm:
>  	usb_put_function(f_acm);
>  err_func_acm:
>  	usb_put_function_instance(fi_serial);
> +err_get_acm:
> +	usb_remove_function(c, f_ecm);
> +err_add_ecm:
> +	usb_put_function(f_ecm);
> +err_get_ecm:
> +	usb_put_function_instance(fi_ecm);
> +err_func_ecm:
>  	return status;
>  }
> 
> @@ -159,6 +173,7 @@ static struct usb_configuration cdc_config_driver =
> {  static int __init cdc_bind(struct usb_composite_dev *cdev)  {
>  	struct usb_gadget	*gadget = cdev->gadget;
> +	struct f_ecm_opts	*ecm_opts;
>  	int			status;
> 
>  	if (!can_support_ecm(cdev->gadget)) {
> @@ -167,11 +182,23 @@ static int __init cdc_bind(struct usb_composite_dev
> *cdev)
>  		return -EINVAL;
>  	}
> 
> -	/* set up network link layer */
> -	the_dev = gether_setup(cdev->gadget, dev_addr, host_addr, host_mac,
> -			       qmult);
> -	if (IS_ERR(the_dev))
> -		return PTR_ERR(the_dev);
> +	fi_ecm = usb_get_function_instance("ecm");

This is ok, we get the instance in cdc_bind and get the function in
cdc_do_config

> +	if (IS_ERR(fi_ecm))
> +		return PTR_ERR(fi_ecm);
> +
> +	ecm_opts = container_of(fi_ecm, struct f_ecm_opts, func_inst);
> +
> +	gether_set_qmult(ecm_opts->net, qmult);
> +	if (!gether_set_host_addr(ecm_opts->net, host_addr))
> +		pr_info("using host ethernet address: %s", host_addr);
> +	if (!gether_set_dev_addr(ecm_opts->net, dev_addr))
> +		pr_info("using self ethernet address: %s", dev_addr);
> +
> +	fi_serial = usb_get_function_instance("acm");

This is ok, we get the instance in cdc_bind and get the function in
cdc_do_config

<snip>

Thanks,

Andrzej

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