On 2021/3/24 11:52, Viresh Kumar wrote:
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 ?"
It can't start until the virtqueue_kick() is called. Call virtqueue_kick
then wait.
