forked from luck/tmp_suning_uos_patched
virtio: Add ability to detach unused buffers from vrings
There's currently no way for a virtio driver to ask for unused buffers, so it has to keep a list itself to reclaim them at shutdown. This is redundant, since virtio_ring stores that information. So add a new hook to do this. Signed-off-by: Shirley Ma <xma@us.ibm.com> Signed-off-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -334,6 +334,30 @@ static bool vring_enable_cb(struct virtqueue *_vq)
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return true;
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}
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static void *vring_detach_unused_buf(struct virtqueue *_vq)
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{
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struct vring_virtqueue *vq = to_vvq(_vq);
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unsigned int i;
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void *buf;
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START_USE(vq);
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for (i = 0; i < vq->vring.num; i++) {
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if (!vq->data[i])
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continue;
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/* detach_buf clears data, so grab it now. */
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buf = vq->data[i];
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detach_buf(vq, i);
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END_USE(vq);
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return buf;
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}
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/* That should have freed everything. */
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BUG_ON(vq->num_free != vq->vring.num);
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END_USE(vq);
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return NULL;
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}
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irqreturn_t vring_interrupt(int irq, void *_vq)
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{
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struct vring_virtqueue *vq = to_vvq(_vq);
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@ -360,6 +384,7 @@ static struct virtqueue_ops vring_vq_ops = {
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.kick = vring_kick,
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.disable_cb = vring_disable_cb,
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.enable_cb = vring_enable_cb,
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.detach_unused_buf = vring_detach_unused_buf,
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};
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struct virtqueue *vring_new_virtqueue(unsigned int num,
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@ -51,6 +51,9 @@ struct virtqueue {
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* This re-enables callbacks; it returns "false" if there are pending
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* buffers in the queue, to detect a possible race between the driver
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* checking for more work, and enabling callbacks.
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* @detach_unused_buf: detach first unused buffer
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* vq: the struct virtqueue we're talking about.
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* Returns NULL or the "data" token handed to add_buf
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*
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* Locking rules are straightforward: the driver is responsible for
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* locking. No two operations may be invoked simultaneously, with the exception
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@ -71,6 +74,7 @@ struct virtqueue_ops {
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void (*disable_cb)(struct virtqueue *vq);
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bool (*enable_cb)(struct virtqueue *vq);
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void *(*detach_unused_buf)(struct virtqueue *vq);
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};
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/**
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