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virtio: document virtio_reset_device

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Looks like most callers get driver/device removal wrong.
Document what's expected of callers.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2022-01-14 15:54:01 -05:00
parent 4fa59ede95
commit c46eccdaad
1 changed files with 16 additions and 0 deletions
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16
drivers/virtio/virtio.c
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@ -202,6 +202,22 @@ static int virtio_features_ok(struct virtio_device *dev)
return 0;
}
/**
* virtio_reset_device - quiesce device for removal
* @dev: the device to reset
*
* Prevents device from sending interrupts and accessing memory.
*
* Generally used for cleanup during driver / device removal.
*
* Once this has been invoked, caller must ensure that
* virtqueue_notify / virtqueue_kick are not in progress.
*
* Note: this guarantees that vq callbacks are not in progress, however caller
* is responsible for preventing access from other contexts, such as a system
* call/workqueue/bh. Invoking virtio_break_device then flushing any such
* contexts is one way to handle that.
* */
void virtio_reset_device(struct virtio_device *dev)
{
dev->config->reset(dev);