Re: [PATCH] fw_cfg: use __ATTR_RO_MODE to define rev sysfs

From: Wei Yang
Date: Wed Feb 27 2019 - 19:49:41 EST


On Wed, Feb 27, 2019 at 08:51:11AM -0500, Michael S. Tsirkin wrote:
>On Wed, Feb 27, 2019 at 01:33:19PM +0800, Wei Yang wrote:
>> On Tue, Feb 26, 2019 at 11:10:06AM -0500, Michael S. Tsirkin wrote:
>> >On Tue, Feb 26, 2019 at 03:31:59PM +0800, Wei Yang wrote:
>> >> Leverage __ATTR_RO_MODE to define rev sysfs instead of using open code
>> >> to define the attribute.
>> >>
>> >> Signed-off-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
>> >> ---
>> >> drivers/firmware/qemu_fw_cfg.c | 13 ++++---------
>> >> 1 file changed, 4 insertions(+), 9 deletions(-)
>> >>
>> >> diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
>> >> index 039e0f91dba8..a1293cbd7adb 100644
>> >> --- a/drivers/firmware/qemu_fw_cfg.c
>> >> +++ b/drivers/firmware/qemu_fw_cfg.c
>> >> @@ -296,18 +296,13 @@ static int fw_cfg_do_platform_probe(struct platform_device *pdev)
>> >> return 0;
>> >> }
>> >>
>> >> -static ssize_t fw_cfg_showrev(struct kobject *k, struct attribute *a, char *buf)
>> >> +static ssize_t fw_cfg_rev_show(struct kobject *k, struct kobj_attribute *a,
>> >> + char *buf)
>> >> {
>> >> return sprintf(buf, "%u\n", fw_cfg_rev);
>> >> }
>> >> -
>> >> -static const struct {
>> >> - struct attribute attr;
>> >> - ssize_t (*show)(struct kobject *k, struct attribute *a, char *buf);
>> >> -} fw_cfg_rev_attr = {
>> >> - .attr = { .name = "rev", .mode = S_IRUSR },
>> >> - .show = fw_cfg_showrev,
>> >> -};
>> >> +static const struct kobj_attribute fw_cfg_rev_attr =
>> >> + __ATTR_RO_MODE(fw_cfg_rev, 0400);
>> >>
>> >> /* fw_cfg_sysfs_entry type */
>> >> struct fw_cfg_sysfs_entry {
>> >
>> >
>> >Looks like this will change the name from "rev" to "fw_cfg_rev".
>> >That's a userspace visible change which we should not do lightly.
>>
>> You are right, I should keep the interface untouched.
>>
>> To keep it user un-visible, we could change like below:
>>
>> - __ATTR_RO(fw_cfg_rev);
>> + __ATTR_RO(rev);
>>
>> Is this better for you?
>
>
>Also why use 0400 and not S_IRUSR?
>

In case this is the proper way to use 0400 and after keeping the name
un-changed, would you mind I sending v2 for this?

>> >> --
>> >> 2.19.1
>>
>> --
>> Wei Yang
>> Help you, Help me

--
Wei Yang
Help you, Help me