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nvdimm: virtio_pmem: use READ_ONCE()/WRITE_ONCE() for wait flags

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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.

Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Signed-off-by: Li Chen <me@linux.beauty>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20260630092338.2094628-8-me@linux.beauty>
This commit is contained in:
Li Chen 2026-06-30 17:23:32 +08:00 committed by Michael S. Tsirkin
parent 811808761e
commit 08e72a5ba1
1 changed files with 7 additions and 7 deletions
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14
drivers/nvdimm/nd_virtio.c
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@ -24,9 +24,9 @@ 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 */
@ -40,7 +40,7 @@ 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);
@ -72,7 +72,7 @@ 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);
@ -93,12 +93,12 @@ 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);
@ -112,7 +112,7 @@ 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);
}