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From: Jie Deng <jie.deng@intel.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
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 08:53:34 +0800	[thread overview]
Message-ID: <5a415dbe-8e3b-2731-cc52-19aeadda1a17@intel.com> (raw)
In-Reply-To: <20210323093839.n7cq7f5poebqdwit@vireshk-i7>


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 ?


No. It starts when wait_for_completion_timeout is called.

So it should be fine here.


>   If not, then completion may be fine where it is.
>

  reply	other threads:[~2021-03-24  0:54 UTC|newest]

Thread overview: 75+ 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  7:27 ` Viresh Kumar
2021-03-23  8:33   ` Jie Deng
2021-03-23  8:37     ` Viresh Kumar
2021-03-23  9:27     ` Arnd Bergmann
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  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  8:18                   ` Wolfram Sang
2021-04-15  8:20                     ` Jie Deng
2021-05-27  6:49                     ` 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 [this message]
2021-03-24  3:52       ` Viresh Kumar
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  6:09     ` Viresh Kumar
2021-03-24  6:41       ` Jie Deng
2021-03-24  6:44         ` Viresh Kumar
2021-04-14  2:07 ` Jie Deng
2021-04-14  3:52   ` Viresh Kumar
2021-04-15  6:25     ` Jie Deng
2021-04-15  3:51 ` Jason Wang
2021-04-15  6:17   ` Jie Deng
2021-06-28  8:39 ` Wolfram Sang
2021-06-28  9:01   ` Arnd Bergmann
2021-06-28  9:25     ` Wolfram Sang
2021-06-28  9:51       ` Arnd Bergmann
2021-06-28 10:13         ` Wolfram Sang
2021-06-28 11:50           ` Arnd Bergmann
2021-06-28 14:58             ` Wolfram Sang
2021-06-29  3:04               ` Jie Deng
2021-06-29  8:30                 ` Wolfram Sang
2021-06-29  9:13                   ` Viresh Kumar
2021-06-29  9:36                     ` Wolfram Sang
2021-06-29  4:10               ` Viresh Kumar
2021-06-29  8:27                 ` Wolfram Sang
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
2021-06-29  3:03     ` Jie Deng
2021-06-29 10:07 ` Wolfram Sang
2021-06-29 10:16   ` Viresh Kumar
2021-06-29 10:23     ` Wolfram Sang
2021-06-29 10:30       ` Viresh Kumar
2021-06-29 10:42         ` Wolfram Sang
2021-06-29 10:43           ` Wolfram Sang
2021-06-29 10:56             ` Viresh Kumar
2021-06-29 11:11               ` Wolfram Sang
2021-06-29 11:16                 ` Viresh Kumar
2021-06-29 11:48                   ` Wolfram Sang
2021-07-05 12:18             ` Viresh Kumar
2021-07-06  1:50               ` Jie Deng
2021-07-22 15:15               ` Wolfram Sang
2021-07-23  2:28                 ` Viresh Kumar
2021-07-23  5:28                   ` Viresh Kumar
2021-06-30  6:45   ` Jie Deng
2021-06-30  7:32     ` Wolfram Sang
2021-06-30  7:51       ` Jie Deng
2021-06-30  7:55         ` Arnd Bergmann
2021-06-30  8:04           ` Wolfram Sang
2021-06-30  8:07           ` Andy Shevchenko
2021-06-30  8:29             ` Arnd Bergmann

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