From: Hans Petter Selasky <h...@bitfrost.no>
> On 02/27/14 08:13, Kohji Okuno wrote:
>> Hi John-Mark,
>> Thank you for you comment.
>> From: John-Mark Gurney <j...@funkthat.com>
>>> Kohji Okuno wrote this message on Thu, Feb 27, 2014 at 14:26 +0900:
>>>> I tried add kqueue I/F to usb_dev.c. I attached my patch.
>>>> What do you think about my patch?
>>> A few comments...
>>> 1) You should just drop the use of flag_iskevent and just
>>> unconditionally call KNOTE... since you have the lock already held,
>>> the cost is minimal (and w/ modern branch prediction, may be cheaper)...
>> Should we set the use of flag_iskevent, when usb_filter_read() and
>> usb_filter_write() return `0'?
>>> 2) Why do you try to start read/write transfers in the _filter? You
>>> should just check to see if data is available and not do work.. This
>>> is also important since kqueue calls the filter just before delivering
>>> the knote to userland to verify that there is still data, and it will
>>> call your _event function for each knote on the fd... The work should
>>> be started through other mechanisms, like read/write syscall or
>>> interrupt or timeout/callout... If it's required to get results from
>>> USB_IF_POLL, then it's fine..
>> I copied from usb_poll().
>> Should we try to start read/write transfers in usb_kqfilter()?
>> Or should not we try to start read/write transfers in poll and kqueue?
>>> 3) I don't see any calls to knlist_destroy... These calls are needed
>>> to clean up the knlist...
>> I understood.
>>> Obviously the #if 1's will need to go...
>>> Also, I don't think your change is against HEAD.. The line numbers
>>> in my version of usb_dev.c are different...
>> I'm sorry.
> I've found two bugs:
> +#if 1
> + knlist_init_mtx(&f_tx->selinfo.si_note, f_rx->priv_mtx);
> Should be:
> +#if 1
> + knlist_init_mtx(&f_tx->selinfo.si_note, f_tx->priv_mtx);
> Event filters need to lock the FIFO's mutex.
> BTW: I'm working on getting the code into -HEAD. I'll run some test before it
> goes in.
Thank you for you comment.
1) You are right.
2) I think that priv_mtx is hold in caller function.
Would you refer to kqueue_scan() in kern/kern_event.c?
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