lkml.org 
[lkml]   [2016]   [Feb]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Date
SubjectRe: [PATCH 8/9] rfkill: Userspace control for airplane mode
On 8 February 2016 at 17:53, Julian Calaby <julian.calaby@gmail.com> wrote:

>> + if (ev.op == RFKILL_OP_AIRPLANE_MODE_RELEASE) {
>> + if (rfkill_apm_owned && !data->is_apm_owner) {
>
> Are you sure this is correct?
>
> In the case that airplane mode isn't owned, the
> rfkill_apm_led_trigger_event() call will be a noop, so we should
> arguably not be calling it.
>

Ok, I'm changing the check to be consistent with _CHANGE, so the call
only succeeds if (rfkill_apm_owned && data->is_apm_owner), and return
an error otherwise.

> Also, should we just fail silently if we're not the owner? I.e. what
> does userspace learn from this op failing and is that useful?
>

I think it is better to return an error every time userspace is trying
to call an operation that it was not supposed to call at a certain
state (without acquiring control of the airplane-mode indicator). If a
program has a logic error that makes it call _RELEASE without calling
_ACQUIRE first, it's easier for the programmer to spot the problem if
we return an error here.

>> + count = -EACCES;
>> + } else {
>> + bool state = rfkill_global_states[RFKILL_TYPE_ALL].cur;
>> +
>> + rfkill_apm_owned = false;
>> + data->is_apm_owner = false;
>> + rfkill_apm_led_trigger_event(state);
>> + }
>> + }
>> +
>> + if (ev.op == RFKILL_OP_AIRPLANE_MODE_CHANGE) {
>> + if (rfkill_apm_owned && data->is_apm_owner)
>> + rfkill_apm_led_trigger_event(ev.soft);
>> + else
>> + count = -EACCES;
>> + }
>> +
>> if (ev.op == RFKILL_OP_CHANGE_ALL)
>> rfkill_update_global_state(ev.type, ev.soft);
>>
>> @@ -1230,7 +1261,17 @@ static int rfkill_fop_release(struct inode *inode, struct file *file)
>> struct rfkill_int_event *ev, *tmp;
>>
>> mutex_lock(&rfkill_global_mutex);
>> +
>> + if (data->is_apm_owner) {
>> + bool state = rfkill_global_states[RFKILL_TYPE_ALL].cur;
>> +
>> + rfkill_apm_owned = false;
>> + data->is_apm_owner = false;
>> + rfkill_apm_led_trigger_event(state);
>
> Also, this code is duplicated from the _RELEASE op above. Would it
> make sense to factor it out into a separate function?
>

Yes, makes sense. This also made me notice I was assigning a negative
value to a size_t variable (count).

>> + }
>> +
>> list_del(&data->list);
>> +
>
> (extra line)
>

After factoring out the _RELEASE code it looks better without this
additional line.

>> mutex_unlock(&rfkill_global_mutex);
>>
>> mutex_destroy(&data->mtx);
>
> Thanks,
>

Thanks for the review, Julian. I'm sending an updated version.

--
João Paulo Rechi Vita
http://about.me/jprvita
\
 
 \ /
  Last update: 2016-02-09 23:01    [W:0.156 / U:37.896 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site