Date: Thu, 10 Jan 2008 14:23:41 +0100
From: Cornelia Huck <cornelia.huck@de.ibm.com>
To: Dave Young <hidave.darkstar@gmail.com>
Cc: Greg KH <gregkh@suse.de>, Stefan Richter <stefanr@s5r6.in-berlin.de>,
       James.Bottomley@hansenpartnership.com, linux-scsi@vger.kernel.org,
       a.zummo@towertech.it, peterz@infradead.org, cbou@mail.ru,
       linux-kernel@vger.kernel.org, David Brownell <david-b@pacbell.net>,
       krh@redhat.com, stern@rowland.harvard.edu, rtc-linux@googlegroups.com,
       spi-devel-general@lists.sourceforge.net,
       linux1394-devel@lists.sourceforge.net, dwmw2@infradead.org,
       davem@davemloft.net, jarkao2@gmail.com
Subject: Re: [PATCH 0/7] convert semaphore to mutex in struct class
Message-ID: <20080110142341.71af4dc5@gondolin.boeblingen.de.ibm.com>
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On Thu, 10 Jan 2008 17:48:43 +0800,
Dave Young <hidave.darkstar@gmail.com> wrote:

Please add a kerneldoc comment for each of the new interfaces.

> +int class_for_each_device(struct class *class, void *data,
> +			   int (*fn)(struct device *, void *))
> +{
> +	struct device *dev;
> +	int error = 0;
> +
> +	if (!class)
> +		return -EINVAL;
> +	mutex_lock(&class->mutex);
> +	list_for_each_entry(dev, &class->devices, node) {
> +		error = fn(dev, data);

Hm, the equivalent _for_each_device() functions all elevate the
device's refcount while calling fn(). I wonder whether we want this
here as well?

> +		if (error)
> +			break;
> +	}
> +	mutex_unlock(&class->mutex);
> +
> +	return error;
> +}
> +EXPORT_SYMBOL_GPL(class_for_each_device);
> +
> +struct device *class_find_device(struct class *class, void *data,
> +				   int (*match)(struct device *, void *))
> +{
> +	struct device *dev;
> +
> +	if (!class)
> +		return NULL;
> +
> +	mutex_lock(&class->mutex);
> +	list_for_each_entry(dev, &class->devices, node)
> +		if (match(dev, data) && get_device(dev))

First get the reference and then drop it if the match function returns
0 to make this analogous to the other _find_device() functions?

> +			break;
> +	mutex_unlock(&class->mutex);
> +
> +	return dev;
> +}
> +EXPORT_SYMBOL_GPL(class_find_device);
> +
> +int class_for_each_child(struct class *class, void *data,
> +			   int (*fn)(struct class_device *, void *))

Haven't looked at the callers, but isn't it better to convert them to
use struct device instead so we don't need to introduce new
class_device api?

> +{
> +	struct class_device *dev;
> +	int error = 0;
> +
> +	if (!class)
> +		return -EINVAL;
> +	mutex_lock(&class->mutex);
> +	list_for_each_entry(dev, &class->children, node) {
> +		error = fn(dev, data);

Same comment as above concerning reference counts.

> +		if (error)
> +			break;
> +	}
> +	mutex_unlock(&class->mutex);
> +
> +	return error;
> +}
> +EXPORT_SYMBOL_GPL(class_for_each_child);
> +
> +struct class_device *class_find_child(struct class *class, void *data,
> +				   int (*match)(struct class_device *, void *))
> +{
> +	struct class_device *dev;
> +
> +	if (!class)
> +		return NULL;
> +
> +	mutex_lock(&class->mutex);
> +	list_for_each_entry(dev, &class->children, node)
> +		if (match(dev, data) && class_device_get(dev))

And here.

> +			break;
> +	mutex_unlock(&class->mutex);
> +
> +	return dev;
> +}
> +EXPORT_SYMBOL_GPL(class_find_child);
> +
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