Hi Luigi,
I attached a minimal change containing two fixes:
- change IFNET_WLOCK into IFNET_RLOCK, to fix the cxgbe issue related
to this thread
- use the proper locking functions for the "worker_lock", unrelated
but needed to avoid the O.S. to trap because of a mismatch between
MTX_SPIN and MTX_DEF.
Cheers,
Vincenzo
2016-12-21 20:30 GMT+01:00 Luigi Rizzo <ri...@iet.unipi.it>:
> On Wed, Dec 21, 2016 at 11:15 AM, Vincenzo Maffione
> <v.maffi...@gmail.com> wrote:
>> Hi,
>> There is no commit related to that in the FreeBSD svn or git.
>>
>> The fix has been published to the github netmap repository here
>> (branch master): https://github.com/luigirizzo/netmap
>>
>> What we should do is to import all the recent updates from the github
>> into HEAD. I can prepare a patch for HEAD, if you wish. Just let me
>> know.
>
> I just checked and the diff between FreeBSD head and netmap head
> in github is almost 3k lines due to a lot of recent refactoring.
> So, if there is an easy way to extract just the locking change that would
> be preferable as an interim solution.
>
> cheers
> luigi
>
>>
>> Cheers,
>> Vincenzo
>>
>>
>> 2016-12-20 21:45 GMT+01:00 Adrian Chadd <adrian.ch...@gmail.com>:
>>> hi,
>>>
>>> What's the commit? We should get it into -HEAD asap.
>>>
>>>
>>> -adrian
>>>
>>>
>>> On 20 December 2016 at 01:25, Vincenzo Maffione <v.maffi...@gmail.com>
>>> wrote:
>>>> Ok, applied to the netmap github repo.
>>>> This fix will be published when Luigi does the next commit on FreeBSD.
>>>>
>>>> Cheers,
>>>> Vincenzo
>>>>
>>>> 2016-12-19 20:05 GMT+01:00 Navdeep Parhar <n...@freebsd.org>:
>>>>> IFNET_RLOCK will work, thanks.
>>>>>
>>>>> Navdeep
>>>>>
>>>>> On Mon, Dec 19, 2016 at 3:21 AM, Vincenzo Maffione <v.maffi...@gmail.com>
>>>>> wrote:
>>>>>> Hi Navdeep,
>>>>>>
>>>>>> Indeed, we have reviewed the code, and we think it is ok to
>>>>>> implement nm_os_ifnet_lock() with IFNET_RLOCK(), instead of using
>>>>>> IFNET_WLOCK().
>>>>>> Since IFNET_RLOCK() results into sx_slock(), this should fix the issue.
>>>>>>
>>>>>> On FreeBSD, this locking is needed to protect a flag read by
>>>>>> nm_iszombie().
>>>>>> However, on Linux the same lock is also needed to protect the call to
>>>>>> the nm_hw_register() callback, so we prefer to have an "unified"
>>>>>> locking scheme, i.e. always calling nm_hw_register under the lock.
>>>>>>
>>>>>> Does this make sense to you? Would it be easy for you to make a quick
>>>>>> test by replacing IFNET_WLOCK with IFNET_RLOCK?
>>>>>>
>>>>>> Thanks,
>>>>>> Vincenzo
>>>>>>
>>>>>> 2016-12-17 23:28 GMT+01:00 Navdeep Parhar <n...@freebsd.org>:
>>>>>>> Luigi, Vincenzo,
>>>>>>>
>>>>>>> The last major update to netmap (r307394 and followups) broke cxgbe's
>>>>>>> native netmap support. The problem is that netmap_hw_reg now holds an
>>>>>>> rw_lock around the driver's netmap_on/off routines. It has always been
>>>>>>> safe for the driver to sleep during these operations but now it panics
>>>>>>> instead.
>>>>>>>
>>>>>>> Why is IFNET_WLOCK needed here? It seems like a regression to disallow
>>>>>>> sleep on the control path.
>>>>>>>
>>>>>>> Regards,
>>>>>>> Navdeep
>>>>>>>
>>>>>>> begin_synchronized_op with the following non-sleepable locks held:
>>>>>>> exclusive rw ifnet_rw (ifnet_rw) r = 0 (0xffffffff8271d680) locked @
>>>>>>> /root/ws/head/sys/dev/netmap/netmap_freebsd.c:95
>>>>>>> stack backtrace:
>>>>>>> #0 0xffffffff810837a5 at witness_debugger+0xe5
>>>>>>> #1 0xffffffff81084d88 at witness_warn+0x3b8
>>>>>>> #2 0xffffffff83ef2bcc at begin_synchronized_op+0x6c
>>>>>>> #3 0xffffffff83f14beb at cxgbe_netmap_reg+0x5b
>>>>>>> #4 0xffffffff809846f1 at netmap_hw_reg+0x81
>>>>>>> #5 0xffffffff809806de at netmap_do_regif+0x19e
>>>>>>> #6 0xffffffff8098121d at netmap_ioctl+0x7ad
>>>>>>> #7 0xffffffff8098682f at freebsd_netmap_ioctl+0x5f
>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Vincenzo Maffione
>>>>>> _______________________________________________
>>>>>> freebsd-net@freebsd.org mailing list
>>>>>> https://lists.freebsd.org/mailman/listinfo/freebsd-net
>>>>>> To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
>>>>
>>>>
>>>>
>>>> --
>>>> Vincenzo Maffione
>>>> _______________________________________________
>>>> freebsd-net@freebsd.org mailing list
>>>> https://lists.freebsd.org/mailman/listinfo/freebsd-net
>>>> To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
>>
>>
>>
>> --
>> Vincenzo Maffione
>
>
>
> --
> -----------------------------------------+-------------------------------
> Prof. Luigi RIZZO, ri...@iet.unipi.it . Dip. di Ing. dell'Informazione
> http://www.iet.unipi.it/~luigi/ . Universita` di Pisa
> TEL +39-050-2217533 . via Diotisalvi 2
> Mobile +39-338-6809875 . 56122 PISA (Italy)
> -----------------------------------------+-------------------------------
--
Vincenzo Maffione
diff --git a/sys/dev/netmap/netmap_freebsd.c b/sys/dev/netmap/netmap_freebsd.c
index fd4592b7b5a..515be6648ea 100644
--- a/sys/dev/netmap/netmap_freebsd.c
+++ b/sys/dev/netmap/netmap_freebsd.c
@@ -92,7 +92,7 @@ nm_os_selinfo_uninit(NM_SELINFO_T *si)
void
nm_os_ifnet_lock(void)
{
- IFNET_WLOCK();
+ IFNET_RLOCK();
}
void
@@ -1021,12 +1021,12 @@ nm_os_kthread_wakeup_worker(struct nm_kthread *nmk)
* but simply that it has changed since the last
* time the kthread saw it.
*/
- mtx_lock(&nmk->worker_lock);
+ mtx_lock_spin(&nmk->worker_lock);
nmk->scheduled++;
if (nmk->worker_ctx.cfg.wchan) {
wakeup((void *)(uintptr_t)nmk->worker_ctx.cfg.wchan);
}
- mtx_unlock(&nmk->worker_lock);
+ mtx_unlock_spin(&nmk->worker_lock);
}
void inline
@@ -1080,10 +1080,10 @@ nm_kthread_worker(void *data)
ctx->worker_fn(ctx->worker_private); /* worker body */
} else {
/* checks if there is a pending notification */
- mtx_lock(&nmk->worker_lock);
+ mtx_lock_spin(&nmk->worker_lock);
if (likely(nmk->scheduled != old_scheduled)) {
old_scheduled = nmk->scheduled;
- mtx_unlock(&nmk->worker_lock);
+ mtx_unlock_spin(&nmk->worker_lock);
ctx->worker_fn(ctx->worker_private); /* worker body */
@@ -1094,7 +1094,7 @@ nm_kthread_worker(void *data)
&nmk->worker_lock, "nmk_ev", hz);
nmk->scheduled++;
}
- mtx_unlock(&nmk->worker_lock);
+ mtx_unlock_spin(&nmk->worker_lock);
}
}
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