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Subject: Re: [PATCH 3/3] nvmem: core: use is_bin_visible for permissions
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org,
        nicholas.johnson-opensource@outlook.com.au
References: <20200324171600.15606-1-srinivas.kandagatla@linaro.org>
 <20200324171600.15606-4-srinivas.kandagatla@linaro.org>
 <20200324174642.GA2524667@kroah.com>
From:   Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Message-ID: <efa9f7c5-f96c-5dcd-26ea-397997b5b5c0@linaro.org>
Date:   Wed, 25 Mar 2020 09:15:39 +0000
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On 24/03/2020 17:46, Greg KH wrote:
> On Tue, Mar 24, 2020 at 05:16:00PM +0000, Srinivas Kandagatla wrote:
>> By using is_bin_visible callback to set permissions will remove a large list
>> of attribute groups. These group permissions can be dynamically derived in
>> the callback.
>>
>> Suggested-by: Greg KH <gregkh@linuxfoundation.org>
>> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
>> ---
>>   drivers/nvmem/nvmem-sysfs.c | 74 +++++++++----------------------------
>>   1 file changed, 18 insertions(+), 56 deletions(-)
>>
>> diff --git a/drivers/nvmem/nvmem-sysfs.c b/drivers/nvmem/nvmem-sysfs.c
>> index 8759c4470012..1ff1801048f6 100644
>> --- a/drivers/nvmem/nvmem-sysfs.c
>> +++ b/drivers/nvmem/nvmem-sysfs.c
>> @@ -103,6 +103,17 @@ static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
>>   
>>   	return count;
>>   }
>> +static umode_t nvmem_bin_attr_is_visible(struct kobject *kobj,
>> +					 struct bin_attribute *attr, int i)
>> +{
>> +	struct device *dev = container_of(kobj, struct device, kobj);
>> +	struct nvmem_device *nvmem = to_nvmem_device(dev);
>> +
>> +	if (nvmem->root_only)
>> +		return nvmem->read_only ? 0400 : 0600;
>> +
>> +	return nvmem->read_only ? 0444 : 0644;
>> +}
> 
> I don't know why this is so hard for me to read, but how about this
> instead:
> 
> static umode_t nvmem_bin_attr_is_visible(struct kobject *kobj,
> 					 struct bin_attribute *attr, int i)
> {
> 	struct device *dev = container_of(kobj, struct device, kobj);
> 	struct nvmem_device *nvmem = to_nvmem_device(dev);
> 	umode_t mode = 0400;
> 
> 	if (!nvmem->root_only)
> 		mode |= 0044;
> 
> 	if (!nvmem->read_only)
> 		mode |= 0200;
> 
> 	return mode;
> }
> 
> Did I get the logic corect?

That looks perfect and matches what is in upstream!
Thanks for suggesting this cleanup!

I will send v2 with this change!

--srini
> 
> thanks,
> 
> greg k-h
>