From: Oliver Neukum <oliver@neukum•org>
To: Dan Williams <dcbw@redhat•com>
Cc: Ming Lei <tom.leiming@gmail•com>,
Elina Pasheva <epasheva@sierrawireless•com>,
Network Development <netdev@vger•kernel.org>,
linux-usb <linux-usb@vger•kernel.org>,
Rory Filer <rfiler@sierrawireless•com>, Phil Sutter <phil@nwl•cc>
Subject: Re: [PATCH 1/2 v4] usbnet: allow status interrupt URB to always be active
Date: Wed, 10 Apr 2013 15:29:24 +0200 [thread overview]
Message-ID: <1542762.9EJvNHlBNo@linux-5eaq.site> (raw)
In-Reply-To: <1365599937.28888.33.camel@dcbw.foobar.com>
On Wednesday 10 April 2013 08:18:57 Dan Williams wrote:
> On Wed, 2013-04-10 at 15:06 +0200, Oliver Neukum wrote:
> > On Wednesday 10 April 2013 07:49:11 Dan Williams wrote:
> > > On Wed, 2013-04-10 at 09:23 +0200, Oliver Neukum wrote:
> > > > On Tuesday 09 April 2013 18:02:27 Dan Williams wrote:
> >
> > > > > +/* Submit the interrupt URB if it hasn't been submitted yet */
> > > > > +static int __usbnet_status_start(struct usbnet *dev, gfp_t mem_flags,
> > > > > + bool force)
> > > > > +{
> > > > > + int ret = 0;
> > > > > + bool submit = false;
> > > > > +
> > > > > + if (!dev->interrupt)
> > > > > + return 0;
> > > > > +
> > > > > + mutex_lock(&dev->interrupt_mutex);
> > > > > +
> > > > > + if (force) {
> > > >
> > > > That design means that interrupt_count isn't accurate if force is used.
> > > > That is extremely ugly.
> > >
> > > True; the problem here is that the URB isn't always submitted when
> > > suspend is used. For example, in a normal driver that doesn't need the
> > > URB submitted all the time, interrupt_count will be 0 while !IFF_UP.
> > > Then if the system suspends, we can't decrement interrupt_count because
> > > it's zero.
> >
> > We don't need to. You ought to understand interrupt_count as
> > valid only while the device is not suspended.
>
> Ok, so at suspend we just drop the count to zero, force-kill the URB,
No, at suspend() ignore interrupt_count. Just kill.
> and then on resume it's not re-submitted again? That seems odd, since
On resume() evaluate interrupt_count.
> the usbnet driver handles submit/resubmit internally if the interface is
> IFF_UP, but when the interface is !IFF_UP then sub-drivers would have to
> track whether they submitted the urb or not, and then clear that on
> suspend? Having separate behavior for when the sub-driver starts the
> URB and when usbnet does seems inconsistent and error-prone.
>
> What approach would you suggest here?
Religiously use interrupt_count. With one exception.
The start/stop helpers are good. Just don't use them at suspend().
[..]
> See my questions above. Then we'd have to have the sub-drivers
> implement suspend/resume hooks so they'd be able to resubmit the
> interrupt URB on resume, and the whole point of this patch was to handle
> all that in usbnet. The sub-drivers don't know what the core driver's
> suspend/resume count is, because dev->suspend_count isn't exposed to
> subdrivers, and thus they don't know whether the device is actually
> suspended or not.
>
> The core problem is this... the sub-driver submits the URB before
> IFF_UP, and then at IFF_UP time usbnet wants to submit the driver.
> Let's say later the sub-driver doesn't need its private interrupt URB
> submission anymore, but it can't kill the URB because usbnet has
> submitted it too. Hence the refcounting.
The refcounting is very good. Just don't mess around with "force"
Regards
Oliver
next prev parent reply other threads:[~2013-04-10 13:28 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-27 14:12 strange behaviour of MC7700 with sierra_net Phil Sutter
[not found] ` <20110727141246.GC29616-2COwY06ShZsYt6otZODPyA@public.gmane.org>
2011-07-27 19:40 ` Dan Williams
[not found] ` <1311795643.17655.13.camel-wKZy7rqYPVb5EHUCmHmTqw@public.gmane.org>
2011-07-28 16:32 ` Phil Sutter
[not found] ` <8F90F944E50427428C60E12A34A309D23424BB0F25@carmd-exchmb01.sierrawireless.local>
[not found] ` <8F90F944E50427428C60E12A34A309D23424BB0F25-3qf8vkpM5jTbmvMHnzRVpW3Pdy6AhKVLXbPIYa3/oNjDOqzlkpFKJg@public.gmane.org>
2011-08-04 16:38 ` Phil Sutter
2013-01-04 16:48 ` [PATCH 1/2] usbnet: allow status interrupt URB to always be active Dan Williams
2013-01-04 16:51 ` [PATCH 2/2] sierra_net: keep status interrupt URB active over netdev open/close Dan Williams
[not found] ` <1357318289.5370.19.camel-wKZy7rqYPVb5EHUCmHmTqw@public.gmane.org>
2013-02-06 18:42 ` [PATCH 2/2 v2] sierra_net: fix issues with SYNC/RESTART messages and interrupt pipe setup Dan Williams
[not found] ` <1360176176.11742.16.camel-wKZy7rqYPVb5EHUCmHmTqw@public.gmane.org>
2013-02-06 20:17 ` Oliver Neukum
2013-02-07 21:09 ` Dan Williams
2013-02-06 21:11 ` Bjørn Mork
2013-02-07 17:06 ` Dan Williams
2013-02-13 11:44 ` Bjørn Mork
2013-02-13 16:34 ` Dan Williams
2013-01-04 22:16 ` [PATCH 1/2] usbnet: allow status interrupt URB to always be active Oliver Neukum
2013-01-05 1:26 ` Dan Williams
2013-01-05 11:01 ` Oliver Neukum
2013-01-05 11:44 ` Bjørn Mork
2013-01-07 15:25 ` Dan Williams
2013-01-14 17:52 ` Dan Williams
[not found] ` <1357349193.19684.3.camel-wKZy7rqYPVb5EHUCmHmTqw@public.gmane.org>
2013-01-05 10:59 ` Bjørn Mork
[not found] ` <87y5g7nbej.fsf-lbf33ChDnrE/G1V5fR+Y7Q@public.gmane.org>
2013-01-07 7:40 ` Oliver Neukum
2013-01-07 15:21 ` Dan Williams
2013-01-11 3:06 ` Ming Lei
2013-01-14 17:23 ` Dan Williams
2013-01-15 1:13 ` Ming Lei
2013-02-06 18:36 ` [PATCH 1/2 v2] " Dan Williams
2013-02-06 20:19 ` Oliver Neukum
2013-03-28 16:30 ` [PATCH 1/2 v3] " Dan Williams
[not found] ` <1364488207.1877.20.camel-wKZy7rqYPVb5EHUCmHmTqw@public.gmane.org>
2013-03-28 16:32 ` [PATCH 2/2 v3] sierra_net: keep status interrupt URB active Dan Williams
[not found] ` <1364488327.1877.22.camel-wKZy7rqYPVb5EHUCmHmTqw@public.gmane.org>
2013-03-29 19:21 ` David Miller
2013-03-29 19:20 ` [PATCH 1/2 v3] usbnet: allow status interrupt URB to always be active David Miller
[not found] ` <CACVXFVMBAzTYZKiE_uSTqr_yB4f7c5_PSnK=LBP6=oWdWwYHfg@mail.gmail.com>
[not found] ` <CACVXFVMBAzTYZKiE_uSTqr_yB4f7c5_PSnK=LBP6=oWdWwYHfg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-04-01 16:04 ` Dan Williams
2013-04-09 23:02 ` [PATCH 1/2 v4] " Dan Williams
2013-04-09 23:05 ` [PATCH 2/2 v4] sierra_net: keep status interrupt URB active Dan Williams
2013-04-10 7:15 ` Oliver Neukum
2013-04-10 14:57 ` Dan Williams
2013-04-10 15:01 ` Oliver Neukum
2013-04-10 7:23 ` [PATCH 1/2 v4] usbnet: allow status interrupt URB to always be active Oliver Neukum
[not found] ` <2328167.HJRXSHNhKT-7ztolUikljGernLeA6q8OA@public.gmane.org>
2013-04-10 12:49 ` Dan Williams
2013-04-10 13:06 ` Oliver Neukum
2013-04-10 13:18 ` Dan Williams
2013-04-10 13:29 ` Oliver Neukum [this message]
[not found] ` <1542762.9EJvNHlBNo-7ztolUikljGernLeA6q8OA@public.gmane.org>
2013-04-10 13:54 ` Dan Williams
[not found] ` <1365602083.28888.40.camel-wKZy7rqYPVb5EHUCmHmTqw@public.gmane.org>
2013-04-10 13:58 ` Oliver Neukum
2013-04-10 15:01 ` Dan Williams
2013-04-10 18:10 ` Oliver Neukum
2013-04-10 20:30 ` [PATCH 1/2 v5] " Dan Williams
2013-04-10 21:35 ` Oliver Neukum
[not found] ` <1365625850.22411.1.camel-wKZy7rqYPVb5EHUCmHmTqw@public.gmane.org>
2013-04-10 20:33 ` [PATCH 2/2 v5] sierra_net: keep status interrupt URB active Dan Williams
2013-04-11 2:31 ` [PATCH 1/2 v5] usbnet: allow status interrupt URB to always be active Ming Lei
2013-04-11 6:50 ` Oliver Neukum
2013-04-11 8:06 ` Bjørn Mork
2013-04-11 8:37 ` Ming Lei
2013-04-11 9:59 ` Oliver Neukum
2013-04-11 10:04 ` Bjørn Mork
2013-04-11 10:09 ` Ming Lei
2013-04-11 10:19 ` Ming Lei
[not found] ` <CACVXFVNn9MQr6JLdin=u642Jb-2ZPfVk8YaBmNdhU0_2e7WJqQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-04-11 10:26 ` Bjørn Mork
2013-04-11 10:30 ` Ming Lei
2013-04-11 11:08 ` Bjørn Mork
[not found] ` <87d2u1wci6.fsf-lbf33ChDnrE/G1V5fR+Y7Q@public.gmane.org>
2013-04-11 11:42 ` Ming Lei
[not found] ` <CACVXFVO13tG606nDHth5rEA9jexj1iFHnry5ktrMpm_aGGTSvw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-04-11 11:54 ` Oliver Neukum
2013-04-11 12:16 ` Ming Lei
2013-04-11 8:09 ` Ming Lei
2013-04-11 9:53 ` Oliver Neukum
2013-04-11 10:03 ` Ming Lei
2013-04-11 11:14 ` Oliver Neukum
2013-04-11 12:11 ` Ming Lei
2013-04-11 12:28 ` Oliver Neukum
2013-04-11 12:59 ` Ming Lei
[not found] ` <CACVXFVPPzva+EwjNdxWsg4FufCc0zzzzvhGH_nLv479vT8VcxQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-04-12 6:37 ` Oliver Neukum
2013-04-12 9:42 ` Ming Lei
2013-04-12 10:02 ` Oliver Neukum
2013-04-12 10:08 ` Ming Lei
2013-04-12 10:13 ` Bjørn Mork
2013-04-11 15:28 ` Dan Williams
2013-04-12 7:28 ` Oliver Neukum
2013-04-15 15:59 ` Dan Williams
2013-04-16 1:15 ` Ming Lei
2013-04-16 7:57 ` Oliver Neukum
[not found] ` <1637650.tuYfvStuVJ-7ztolUikljGernLeA6q8OA@public.gmane.org>
2013-04-17 1:56 ` Ming Lei
2013-04-17 6:55 ` Oliver Neukum
[not found] ` <5581442.KzM2iaDSQ0-7ztolUikljGernLeA6q8OA@public.gmane.org>
2013-04-18 3:51 ` Ming Lei
2013-04-19 8:25 ` Oliver Neukum
2013-04-24 12:31 ` Dan Williams
2013-04-25 13:00 ` Oliver Neukum
[not found] ` <1365548547.23372.2.camel-wKZy7rqYPVb5EHUCmHmTqw@public.gmane.org>
2013-04-10 13:25 ` [PATCH 1/2 v4] " Bjørn Mork
2013-04-10 13:31 ` Oliver Neukum
[not found] ` <1365604263.28888.56.camel@dcbw.foobar.com>
2013-04-10 15:21 ` Bjørn Mork
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1542762.9EJvNHlBNo@linux-5eaq.site \
--to=oliver@neukum$(echo .)org \
--cc=dcbw@redhat$(echo .)com \
--cc=epasheva@sierrawireless$(echo .)com \
--cc=linux-usb@vger$(echo .)kernel.org \
--cc=netdev@vger$(echo .)kernel.org \
--cc=phil@nwl$(echo .)cc \
--cc=rfiler@sierrawireless$(echo .)com \
--cc=tom.leiming@gmail$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox