linux-kernel - Re: [PATCH] ACPI: Add GPIO-signaled event emulator.

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Message-ID: <53F60A92.4040702@linaro.org>
Date:	Thu, 21 Aug 2014 17:04:50 +0200
From:	Tomasz Nowicki <tomasz.nowicki@...aro.org>
To:	Mika Westerberg <mika.westerberg@...ux.intel.com>
CC:	rjw@...ysocki.net, linus.walleij@...aro.org, gnurou@...il.com,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linaro-acpi@...ts.linaro.org
Subject: Re: [PATCH] ACPI: Add GPIO-signaled event emulator.

On 21.08.2014 16:54, Mika Westerberg wrote:
> On Thu, Aug 21, 2014 at 04:39:46PM +0200, Tomasz Nowicki wrote:
>>>> +{
>>>> +	struct gpio_pin_data *pin_data, *temp;
>>>> +
>>>> +	list_for_each_entry_safe(pin_data, temp, &pin_data_list, list)
>>>> +		kfree(pin_data);
>>>
>>> I suppose you want to first remove the directory entries and then the
>>> pin data. Otherwise if you get pre-empted at this point and someone
>>> tries to use your debugfs files, bad things might happen.
>> Good catch!
>>
>>>
>>>> +
>>>> +	debugfs_remove_recursive(acpi_evt_debugfs_dir);
>>>
>>> Since this already removes everything below this dentry, why do you need
>>> to store the pointer in gpio_pin_parent_data?
>> Not sure I got the question.
>>
>> GPIO device instance (debugfs dir) is parent for all its pins (debugfs
>> nodes). I am using gpio_pin_parent_data as container to pass info for all
>> children so I can create debugfs node inside of parent related debugfs dir.
>>
>> pin_data_list, however, is used to keep pointers to allocated memory (one
>> for each pins). debugfs_remove_recursive won't free it.
>
> Yes but it removes the debugfs entries below so you don't need to store
> the children debugfs dentries.
>
I don't, gpio_pin_parent_data (local variable) keeps pointer to *parent 
debugfs dentries* only. gpio_pin_parent_data name might be misleading, I 
will rename it to gpio_parent_data in next version.

Regards,
Tomasz
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