linux-kernel - Re: [PATCH v2] watchdog: ziirave_wdt: Add support to upload the firmware.

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Date:	Thu, 21 Jul 2016 06:24:53 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Enric Balletbo Serra <eballetbo@...il.com>
Cc:	Enric Balletbo i Serra <enric.balletbo@...labora.com>,
	linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
	Wim Van Sebroeck <wim@...ana.be>,
	Martyn Welch <martyn.welch@...labora.com>
Subject: Re: [PATCH v2] watchdog: ziirave_wdt: Add support to upload the
 firmware.

On 07/21/2016 01:59 AM, Enric Balletbo Serra wrote:

[ ... ]

>>>
>>> +static ssize_t ziirave_wdt_sysfs_store_firm(struct device *dev,
>>> +                                           struct device_attribute *attr,
>>> +                                           const char *buf, size_t count)
>>> +{
>>> +       struct i2c_client *client = to_i2c_client(dev->parent);
>>> +       struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
>>> +       const struct firmware *fw;
>>> +       int err;
>>> +
>>
>>
>> What happens if this file is opened twice and written in parallel ?
>> What if any
>> other attribute is accessed while the firmware download is ongoing ?
>>
>
> Good point. So you think I need to protect all with mutexes or there

Yes, you have to protect any possible damaging parallel access with mutexes.

> is another way? From a quick look on other drivers i didn't see this
> kind of protection (something to look at in the future)
>

Really ? Can you point me to some examples ? This would be a bug.

You'll have to fix the to get your patch accepted. Pointing to other
examples with the same or a similar bug is not an argument.

Thanks,
Guenter