> Use READ_ONCE()/WRITE_ONCE() for the wait_event() flags (done and > wq_buf_avail). They are observed by waiters without pmem_lock, so make > the accesses explicit single loads/stores and avoid compiler > reordering/caching across the wait/wake paths. > > Signed-off-by: Li Chen <[email protected]>
Acked-by: Pankaj Gupta <[email protected] > --- > v2->v3: > - Split out READ_ONCE()/WRITE_ONCE() updates from patch 3/7 (no functional > change intended). > v3->v4: > - Rebased onto v7.1-rc7 and renumbered after the flush error patches. > > drivers/nvdimm/nd_virtio.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c > index 8ed4d6b3a9284..da829e9f4bdff 100644 > --- a/drivers/nvdimm/nd_virtio.c > +++ b/drivers/nvdimm/nd_virtio.c > @@ -18,9 +18,9 @@ static void virtio_pmem_wake_one_waiter(struct virtio_pmem > *vpmem) > > req_buf = list_first_entry(&vpmem->req_list, > struct virtio_pmem_request, list); > - req_buf->wq_buf_avail = true; > + list_del_init(&req_buf->list); > + WRITE_ONCE(req_buf->wq_buf_avail, true); > wake_up(&req_buf->wq_buf); > - list_del(&req_buf->list); > } > > /* The interrupt handler */ > @@ -34,7 +34,7 @@ void virtio_pmem_host_ack(struct virtqueue *vq) > spin_lock_irqsave(&vpmem->pmem_lock, flags); > while ((req_data = virtqueue_get_buf(vq, &len)) != NULL) { > virtio_pmem_wake_one_waiter(vpmem); > - req_data->done = true; > + WRITE_ONCE(req_data->done, true); > wake_up(&req_data->host_acked); > } > spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > @@ -66,7 +66,7 @@ static int virtio_pmem_flush(struct nd_region *nd_region) > if (!req_data) > return -ENOMEM; > > - req_data->done = false; > + WRITE_ONCE(req_data->done, false); > init_waitqueue_head(&req_data->host_acked); > init_waitqueue_head(&req_data->wq_buf); > INIT_LIST_HEAD(&req_data->list); > @@ -87,12 +87,12 @@ static int virtio_pmem_flush(struct nd_region *nd_region) > GFP_ATOMIC)) == -ENOSPC) { > > dev_info(&vdev->dev, "failed to send command to virtio pmem > device, no free slots in the virtqueue\n"); > - req_data->wq_buf_avail = false; > + WRITE_ONCE(req_data->wq_buf_avail, false); > list_add_tail(&req_data->list, &vpmem->req_list); > spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > > /* A host response results in "host_ack" getting called */ > - wait_event(req_data->wq_buf, req_data->wq_buf_avail); > + wait_event(req_data->wq_buf, > READ_ONCE(req_data->wq_buf_avail)); > spin_lock_irqsave(&vpmem->pmem_lock, flags); > } > err1 = virtqueue_kick(vpmem->req_vq); > @@ -106,7 +106,7 @@ static int virtio_pmem_flush(struct nd_region *nd_region) > err = -EIO; > } else { > /* A host response results in "host_ack" getting called */ > - wait_event(req_data->host_acked, req_data->done); > + wait_event(req_data->host_acked, READ_ONCE(req_data->done)); > err = le32_to_cpu(req_data->resp.ret); > } > > -- > 2.52.0
