Messages in this thread | | | Subject | Re: [PATCH v10] i2c: virtio: add a virtio i2c frontend driver | From | Jie Deng <> | Date | Wed, 24 Mar 2021 08:53:34 +0800 |
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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. >
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