lkml.org 
[lkml]   [2007]   [Apr]   [5]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateThu, 05 Apr 2007 14:47:19 +0800
FromLi Yu <>
SubjectRe: [linux-usb-devel] [RFC] HID bus design overview.
Dmitry Torokhov wrote:
>>> +int hid_open(struct hid_device *hid)
>>> +{
>>> +	struct hid_transport *tl;
>>> +	int ret;
>>> +
>>> +	if (hid->driver->open)
>>> +		return hid->driver->open(hid);
>>> +	ret = 0;
>>> +	spin_lock(&hid_lock);
>>> +	tl =  hid_transports[hid->bus];
>>> +	if (tl->open)
>>> +		ret = tl->open(hid);
>>> +	spin_unlock(&hid_lock);
>>> +	return ret;
>>> +}
>>> 
>>> 
>> Spinlock is not the best choise here, I'd expect most ->open()
>> implementation wait on some IO.
>>
>> 
>> 
> Yes, I agree! Also, there have another code access hid_transports[]
> without spin it!
>
> 
I think I found out the resolve means for this: using the refcnt of
hid_transport->module,
so we can read access hid_transports[] safely without any lock protection.






-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-04-05 06:51    [from the cache]
©2003-2008