[PATCH] staging: most: do not show interface dependent attrs by default in sysfs

Christian Gromm christian.gromm at microchip.com
Wed Aug 8 14:51:26 UTC 2018


On 08.08.2018 14:10, Greg KH wrote:
> On Mon, Aug 06, 2018 at 12:03:10PM +0200, Christian Gromm wrote:
>> The channel attribute dbr_size is only relevant for the DIM2 interface. So
>> is the packets_per_xact for USB. Currently, all attrs are shown by default
>> in sysfs for any channel. To get a clean content of a channel directory,
>> this patch makes the attributes show up only on the channel they belong to.
>>
>> Signed-off-by: Christian Gromm <christian.gromm at microchip.com>
>> ---
>>   drivers/staging/most/core.c      | 12 +++++++++---
>>   drivers/staging/most/core.h      |  5 +++++
>>   drivers/staging/most/dim2/dim2.c |  1 +
>>   drivers/staging/most/usb/usb.c   |  1 +
>>   4 files changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/staging/most/core.c b/drivers/staging/most/core.c
>> index f4c4646..19694a1 100644
>> --- a/drivers/staging/most/core.c
>> +++ b/drivers/staging/most/core.c
>> @@ -25,6 +25,7 @@
>>   
>>   #define MAX_CHANNELS	64
>>   #define STRING_SIZE	80
>> +#define MAX_NUM_ATTRS	14
>>   
>>   static struct ida mdev_id;
>>   static int dummy_num_buffers;
>> @@ -459,7 +460,7 @@ static DEVICE_ATTR_RW(set_subbuffer_size);
>>   static DEVICE_ATTR_RW(set_packets_per_xact);
>>   static DEVICE_ATTR_RW(set_dbr_size);
>>   
>> -static struct attribute *channel_attrs[] = {
>> +static struct attribute *channel_attrs[MAX_NUM_ATTRS] = {
> 
> Oh, this is ripe for abuse :)
> 
>>   	DEV_ATTR(available_directions),
>>   	DEV_ATTR(available_datatypes),
>>   	DEV_ATTR(number_of_packet_buffers),
>> @@ -472,8 +473,6 @@ static struct attribute *channel_attrs[] = {
>>   	DEV_ATTR(set_direction),
>>   	DEV_ATTR(set_datatype),
>>   	DEV_ATTR(set_subbuffer_size),
>> -	DEV_ATTR(set_packets_per_xact),
>> -	DEV_ATTR(set_dbr_size),
>>   	NULL,
>>   };
>>   
>> @@ -1416,6 +1415,13 @@ int most_register_interface(struct most_interface *iface)
>>   	iface->dev.init_name = iface->p->name;
>>   	iface->dev.bus = &mc.bus;
>>   	iface->dev.parent = &mc.dev;
>> +	if (iface->extra_attrs == XACT_ATTRS) {
>> +		channel_attrs[12] = DEV_ATTR(set_packets_per_xact);
>> +		channel_attrs[13] = NULL;
>> +	} else if (iface->extra_attrs == DBR_ATTRS) {
>> +		channel_attrs[12] = DEV_ATTR(set_dbr_size);
>> +		channel_attrs[13] = NULL;
>> +	}
> 
> No, please use the proper way of doing this.  Your attribute can have a
> callback when it is being created to test if it should be created or
> not.  Use that, this is exactly what it is there for.
> 
Hmm, I don't see how to hook a custom callback to a device attribute
as its structure does not provide any pointer to do so.

I went down the rabbit hole staring at "device_register", but
I couldn't find any code that checks for such a function before
adding the attributes to sysfs.

Can you please point out some driver code that makes use of such
a callback you are talking about? That would be nice.

all the best,
Chris


More information about the devel mailing list