From: Viresh Kumar <viresh.kumar@linaro.org>
To: Jie Deng <jie.deng@intel.com>
Cc: linux-i2c@vger.kernel.org,
virtualization@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, mst@redhat.com, wsa@kernel.org,
jasowang@redhat.com, wsa+renesas@sang-engineering.com,
andriy.shevchenko@linux.intel.com, conghui.chen@intel.com,
arnd@arndb.de, kblaiech@mellanox.com,
jarkko.nikula@linux.intel.com, Sergey.Semin@baikalelectronics.ru,
rppt@kernel.org, loic.poulain@linaro.org, tali.perry1@gmail.com,
u.kleine-koenig@pengutronix.de, bjorn.andersson@linaro.org,
yu1.wang@intel.com, shuo.a.liu@intel.com, stefanha@redhat.com,
pbonzini@redhat.com
Subject: Re: [PATCH v10] i2c: virtio: add a virtio i2c frontend driver
Date: Wed, 24 Mar 2021 09:22:25 +0530 [thread overview]
Message-ID: <20210324035225.skkllxexjl65gs6x@vireshk-i7> (raw)
In-Reply-To: <5a415dbe-8e3b-2731-cc52-19aeadda1a17@intel.com>
On 24-03-21, 08:53, Jie Deng wrote:
>
> On 2021/3/23 17:38, Viresh Kumar wrote:
> > On 23-03-21, 14:31, Viresh Kumar wrote:
> > > On 23-03-21, 22:19, Jie Deng wrote:
> > > > +static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
> > > > +{
> > > > + struct virtio_i2c *vi = i2c_get_adapdata(adap);
> > > > + struct virtqueue *vq = vi->vq;
> > > > + struct virtio_i2c_req *reqs;
> > > > + unsigned long time_left;
> > > > + int ret, nr;
> > > > +
> > > > + reqs = kcalloc(num, sizeof(*reqs), GFP_KERNEL);
> > > > + if (!reqs)
> > > > + return -ENOMEM;
> > > > +
> > > > + mutex_lock(&vi->lock);
> > > > +
> > > > + ret = virtio_i2c_send_reqs(vq, reqs, msgs, num);
> > > > + if (ret == 0)
> > > > + goto err_unlock_free;
> > > > +
> > > > + nr = ret;
> > > > + reinit_completion(&vi->completion);
> > > I think I may have found a possible bug here. This reinit_completion() must
> > > happen before we call virtio_i2c_send_reqs(). It is certainly possible (surely
> > > in corner cases) that virtio_i2c_msg_done() may get called right after
> > > virtio_i2c_send_reqs() and before we were able to call reinit_completion(). And
> > > in that case we will never see the completion happen at all.
> > >
> > > > + virtqueue_kick(vq);
> > I may have misread this. Can the actually start before virtqueue_kick() is
> > called ?
I didn't write it properly here. I wanted to say,
"Can the _transfer_ actually start before virtqueue_kick() is called ?"
> No. It starts when wait_for_completion_timeout is called.
No, the transfer doesn't have anything to do with wait_for_completion_timeout().
And if complete() gets called before wait_for_completion_timeout() is called,
then wait_for_completion_timeout() will simply return back.
> So it should be fine here.
>
>
> > If not, then completion may be fine where it is.
> >
--
viresh
next prev parent reply other threads:[~2021-03-24 3:53 UTC|newest]
Thread overview: 114+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-23 14:19 [PATCH v10] i2c: virtio: add a virtio i2c frontend driver Jie Deng
2021-03-23 14:19 ` Jie Deng
2021-03-23 7:27 ` Viresh Kumar
2021-03-23 8:33 ` Jie Deng
2021-03-23 8:33 ` Jie Deng
2021-03-23 8:37 ` Viresh Kumar
2021-03-23 9:27 ` Arnd Bergmann
2021-03-23 9:27 ` Arnd Bergmann
2021-03-24 1:17 ` Jie Deng
2021-03-24 1:17 ` Jie Deng
2021-03-24 4:00 ` Viresh Kumar
2021-04-15 6:45 ` Viresh Kumar
2021-04-15 6:56 ` Jie Deng
2021-04-15 6:56 ` Jie Deng
2021-04-15 7:15 ` Viresh Kumar
2021-04-15 7:21 ` Wolfram Sang
2021-04-15 7:24 ` Viresh Kumar
2021-04-15 7:28 ` Wolfram Sang
2021-04-15 7:37 ` Viresh Kumar
2021-04-15 8:15 ` Jie Deng
2021-04-15 8:15 ` Jie Deng
2021-04-15 8:18 ` Wolfram Sang
2021-04-15 8:20 ` Jie Deng
2021-04-15 8:20 ` Jie Deng
2021-05-27 6:49 ` Jie Deng
2021-05-27 6:49 ` Jie Deng
2021-05-12 1:37 ` Jie Deng
2021-05-12 1:37 ` Jie Deng
2021-03-23 9:01 ` Viresh Kumar
2021-03-23 9:38 ` Viresh Kumar
2021-03-24 0:53 ` Jie Deng
2021-03-24 0:53 ` Jie Deng
2021-03-24 3:52 ` Viresh Kumar [this message]
2021-03-24 4:00 ` Jie Deng
2021-03-24 4:00 ` Jie Deng
2021-03-24 4:02 ` Viresh Kumar
2021-03-24 4:20 ` Viresh Kumar
2021-03-24 6:05 ` Jie Deng
2021-03-24 6:05 ` Jie Deng
2021-03-24 6:09 ` Viresh Kumar
2021-03-24 6:41 ` Jie Deng
2021-03-24 6:41 ` Jie Deng
2021-03-24 6:44 ` Viresh Kumar
2021-04-14 2:07 ` Jie Deng
2021-04-14 2:07 ` Jie Deng
2021-04-14 3:52 ` Viresh Kumar
2021-04-15 6:25 ` Jie Deng
2021-04-15 6:25 ` Jie Deng
2021-04-15 3:51 ` Jason Wang
2021-04-15 3:51 ` Jason Wang
2021-04-15 6:17 ` Jie Deng
2021-04-15 6:17 ` Jie Deng
2021-06-28 8:39 ` Wolfram Sang
2021-06-28 9:01 ` Arnd Bergmann
2021-06-28 9:01 ` Arnd Bergmann
2021-06-28 9:25 ` Wolfram Sang
2021-06-28 9:51 ` Arnd Bergmann
2021-06-28 9:51 ` Arnd Bergmann
2021-06-28 10:13 ` Wolfram Sang
2021-06-28 11:50 ` Arnd Bergmann
2021-06-28 11:50 ` Arnd Bergmann
2021-06-28 14:58 ` Wolfram Sang
2021-06-29 3:04 ` Jie Deng
2021-06-29 3:04 ` Jie Deng
2021-06-29 8:30 ` Wolfram Sang
2021-06-29 9:13 ` Viresh Kumar
2021-06-29 9:13 ` Viresh Kumar
2021-06-29 9:36 ` Wolfram Sang
2021-06-29 4:10 ` Viresh Kumar
2021-06-29 4:10 ` Viresh Kumar
2021-06-29 8:27 ` Wolfram Sang
2021-06-29 8:52 ` Viresh Kumar
2021-06-29 8:52 ` Viresh Kumar
2021-06-29 9:07 ` Wolfram Sang
2021-06-30 14:38 ` Wolfram Sang
2021-06-30 15:09 ` Viresh Kumar
2021-06-30 15:09 ` Viresh Kumar
2021-06-29 3:03 ` Jie Deng
2021-06-29 3:03 ` Jie Deng
2021-06-29 10:07 ` Wolfram Sang
2021-06-29 10:16 ` Viresh Kumar
2021-06-29 10:16 ` Viresh Kumar
2021-06-29 10:23 ` Wolfram Sang
2021-06-29 10:30 ` Viresh Kumar
2021-06-29 10:30 ` Viresh Kumar
2021-06-29 10:42 ` Wolfram Sang
2021-06-29 10:43 ` Wolfram Sang
2021-06-29 10:56 ` Viresh Kumar
2021-06-29 10:56 ` Viresh Kumar
2021-06-29 11:11 ` Wolfram Sang
2021-06-29 11:16 ` Viresh Kumar
2021-06-29 11:16 ` Viresh Kumar
2021-06-29 11:48 ` Wolfram Sang
2021-07-05 12:18 ` Viresh Kumar
2021-07-05 12:18 ` Viresh Kumar
2021-07-06 1:50 ` Jie Deng
2021-07-06 1:50 ` Jie Deng
2021-07-22 15:15 ` Wolfram Sang
2021-07-23 2:28 ` Viresh Kumar
2021-07-23 2:28 ` Viresh Kumar
2021-07-23 5:28 ` Viresh Kumar
2021-07-23 5:28 ` Viresh Kumar
2021-06-30 6:45 ` Jie Deng
2021-06-30 6:45 ` Jie Deng
2021-06-30 7:32 ` Wolfram Sang
2021-06-30 7:51 ` Jie Deng
2021-06-30 7:51 ` Jie Deng
2021-06-30 7:55 ` Arnd Bergmann
2021-06-30 7:55 ` Arnd Bergmann
2021-06-30 8:04 ` Wolfram Sang
2021-06-30 8:07 ` Andy Shevchenko
2021-06-30 8:07 ` Andy Shevchenko
2021-06-30 8:29 ` Arnd Bergmann
2021-06-30 8:29 ` Arnd Bergmann
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