virtio_ring: put split ring functions together

Put the xxx_split() functions together to make the
code more readable and avoid misuse after introducing
the packed ring. There is no functional change.

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 271 insertions, 254 deletions

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 29fab2fb39cb..7cd40a2a0d21 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -113,6 +113,11 @@ struct vring_virtqueue {
 	struct vring_desc_state desc_state[];
 };
 
+
+/*
+ * Helpers.
+ */
+
 #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
 
 /*
@@ -200,6 +205,20 @@ static dma_addr_t vring_map_single(const struct vring_virtqueue *vq,
 			      cpu_addr, size, direction);
 }
 
+static int vring_mapping_error(const struct vring_virtqueue *vq,
+			       dma_addr_t addr)
+{
+	if (!vring_use_dma_api(vq->vq.vdev))
+		return 0;
+
+	return dma_mapping_error(vring_dma_dev(vq), addr);
+}
+
+
+/*
+ * Split ring specific functions - *_split().
+ */
+
 static void vring_unmap_one_split(const struct vring_virtqueue *vq,
 				  struct vring_desc *desc)
 {
@@ -225,15 +244,6 @@ static void vring_unmap_one_split(const struct vring_virtqueue *vq,
 	}
 }
 
-static int vring_mapping_error(const struct vring_virtqueue *vq,
-			       dma_addr_t addr)
-{
-	if (!vring_use_dma_api(vq->vq.vdev))
-		return 0;
-
-	return dma_mapping_error(vring_dma_dev(vq), addr);
-}
-
 static struct vring_desc *alloc_indirect_split(struct virtqueue *_vq,
 					       unsigned int total_sg,
 					       gfp_t gfp)
@@ -435,6 +445,256 @@ unmap_release:
 	return -EIO;
 }
 
+static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	u16 new, old;
+	bool needs_kick;
+
+	START_USE(vq);
+	/* We need to expose available array entries before checking avail
+	 * event. */
+	virtio_mb(vq->weak_barriers);
+
+	old = vq->avail_idx_shadow - vq->num_added;
+	new = vq->avail_idx_shadow;
+	vq->num_added = 0;
+
+#ifdef DEBUG
+	if (vq->last_add_time_valid) {
+		WARN_ON(ktime_to_ms(ktime_sub(ktime_get(),
+					      vq->last_add_time)) > 100);
+	}
+	vq->last_add_time_valid = false;
+#endif
+
+	if (vq->event) {
+		needs_kick = vring_need_event(virtio16_to_cpu(_vq->vdev, vring_avail_event(&vq->vring)),
+					      new, old);
+	} else {
+		needs_kick = !(vq->vring.used->flags & cpu_to_virtio16(_vq->vdev, VRING_USED_F_NO_NOTIFY));
+	}
+	END_USE(vq);
+	return needs_kick;
+}
+
+static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
+			     void **ctx)
+{
+	unsigned int i, j;
+	__virtio16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
+
+	/* Clear data ptr. */
+	vq->desc_state[head].data = NULL;
+
+	/* Put back on free list: unmap first-level descriptors and find end */
+	i = head;
+
+	while (vq->vring.desc[i].flags & nextflag) {
+		vring_unmap_one_split(vq, &vq->vring.desc[i]);
+		i = virtio16_to_cpu(vq->vq.vdev, vq->vring.desc[i].next);
+		vq->vq.num_free++;
+	}
+
+	vring_unmap_one_split(vq, &vq->vring.desc[i]);
+	vq->vring.desc[i].next = cpu_to_virtio16(vq->vq.vdev, vq->free_head);
+	vq->free_head = head;
+
+	/* Plus final descriptor */
+	vq->vq.num_free++;
+
+	if (vq->indirect) {
+		struct vring_desc *indir_desc = vq->desc_state[head].indir_desc;
+		u32 len;
+
+		/* Free the indirect table, if any, now that it's unmapped. */
+		if (!indir_desc)
+			return;
+
+		len = virtio32_to_cpu(vq->vq.vdev, vq->vring.desc[head].len);
+
+		BUG_ON(!(vq->vring.desc[head].flags &
+			 cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT)));
+		BUG_ON(len == 0 || len % sizeof(struct vring_desc));
+
+		for (j = 0; j < len / sizeof(struct vring_desc); j++)
+			vring_unmap_one_split(vq, &indir_desc[j]);
+
+		kfree(indir_desc);
+		vq->desc_state[head].indir_desc = NULL;
+	} else if (ctx) {
+		*ctx = vq->desc_state[head].indir_desc;
+	}
+}
+
+static inline bool more_used_split(const struct vring_virtqueue *vq)
+{
+	return vq->last_used_idx != virtio16_to_cpu(vq->vq.vdev, vq->vring.used->idx);
+}
+
+static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
+					 unsigned int *len,
+					 void **ctx)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	void *ret;
+	unsigned int i;
+	u16 last_used;
+
+	START_USE(vq);
+
+	if (unlikely(vq->broken)) {
+		END_USE(vq);
+		return NULL;
+	}
+
+	if (!more_used_split(vq)) {
+		pr_debug("No more buffers in queue\n");
+		END_USE(vq);
+		return NULL;
+	}
+
+	/* Only get used array entries after they have been exposed by host. */
+	virtio_rmb(vq->weak_barriers);
+
+	last_used = (vq->last_used_idx & (vq->vring.num - 1));
+	i = virtio32_to_cpu(_vq->vdev, vq->vring.used->ring[last_used].id);
+	*len = virtio32_to_cpu(_vq->vdev, vq->vring.used->ring[last_used].len);
+
+	if (unlikely(i >= vq->vring.num)) {
+		BAD_RING(vq, "id %u out of range\n", i);
+		return NULL;
+	}
+	if (unlikely(!vq->desc_state[i].data)) {
+		BAD_RING(vq, "id %u is not a head!\n", i);
+		return NULL;
+	}
+
+	/* detach_buf_split clears data, so grab it now. */
+	ret = vq->desc_state[i].data;
+	detach_buf_split(vq, i, ctx);
+	vq->last_used_idx++;
+	/* If we expect an interrupt for the next entry, tell host
+	 * by writing event index and flush out the write before
+	 * the read in the next get_buf call. */
+	if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
+		virtio_store_mb(vq->weak_barriers,
+				&vring_used_event(&vq->vring),
+				cpu_to_virtio16(_vq->vdev, vq->last_used_idx));
+
+#ifdef DEBUG
+	vq->last_add_time_valid = false;
+#endif
+
+	END_USE(vq);
+	return ret;
+}
+
+static void virtqueue_disable_cb_split(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
+		vq->avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
+		if (!vq->event)
+			vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow);
+	}
+}
+
+static unsigned virtqueue_enable_cb_prepare_split(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	u16 last_used_idx;
+
+	START_USE(vq);
+
+	/* We optimistically turn back on interrupts, then check if there was
+	 * more to do. */
+	/* Depending on the VIRTIO_RING_F_EVENT_IDX feature, we need to
+	 * either clear the flags bit or point the event index at the next
+	 * entry. Always do both to keep code simple. */
+	if (vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
+		vq->avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
+		if (!vq->event)
+			vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow);
+	}
+	vring_used_event(&vq->vring) = cpu_to_virtio16(_vq->vdev, last_used_idx = vq->last_used_idx);
+	END_USE(vq);
+	return last_used_idx;
+}
+
+static bool virtqueue_poll_split(struct virtqueue *_vq, unsigned last_used_idx)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	return (u16)last_used_idx != virtio16_to_cpu(_vq->vdev,
+			vq->vring.used->idx);
+}
+
+static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	u16 bufs;
+
+	START_USE(vq);
+
+	/* We optimistically turn back on interrupts, then check if there was
+	 * more to do. */
+	/* Depending on the VIRTIO_RING_F_USED_EVENT_IDX feature, we need to
+	 * either clear the flags bit or point the event index at the next
+	 * entry. Always update the event index to keep code simple. */
+	if (vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
+		vq->avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
+		if (!vq->event)
+			vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow);
+	}
+	/* TODO: tune this threshold */
+	bufs = (u16)(vq->avail_idx_shadow - vq->last_used_idx) * 3 / 4;
+
+	virtio_store_mb(vq->weak_barriers,
+			&vring_used_event(&vq->vring),
+			cpu_to_virtio16(_vq->vdev, vq->last_used_idx + bufs));
+
+	if (unlikely((u16)(virtio16_to_cpu(_vq->vdev, vq->vring.used->idx) - vq->last_used_idx) > bufs)) {
+		END_USE(vq);
+		return false;
+	}
+
+	END_USE(vq);
+	return true;
+}
+
+static void *virtqueue_detach_unused_buf_split(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	unsigned int i;
+	void *buf;
+
+	START_USE(vq);
+
+	for (i = 0; i < vq->vring.num; i++) {
+		if (!vq->desc_state[i].data)
+			continue;
+		/* detach_buf_split clears data, so grab it now. */
+		buf = vq->desc_state[i].data;
+		detach_buf_split(vq, i, NULL);
+		vq->avail_idx_shadow--;
+		vq->vring.avail->idx = cpu_to_virtio16(_vq->vdev, vq->avail_idx_shadow);
+		END_USE(vq);
+		return buf;
+	}
+	/* That should have freed everything. */
+	BUG_ON(vq->vq.num_free != vq->vring.num);
+
+	END_USE(vq);
+	return NULL;
+}
+
+
+/*
+ * Generic functions and exported symbols.
+ */
+
 static inline int virtqueue_add(struct virtqueue *_vq,
 				struct scatterlist *sgs[],
 				unsigned int total_sg,
@@ -474,6 +734,7 @@ int virtqueue_add_sgs(struct virtqueue *_vq,
 	/* Count them first. */
 	for (i = 0; i < out_sgs + in_sgs; i++) {
 		struct scatterlist *sg;
+
 		for (sg = sgs[i]; sg; sg = sg_next(sg))
 			total_sg++;
 	}
@@ -550,39 +811,6 @@ int virtqueue_add_inbuf_ctx(struct virtqueue *vq,
 }
 EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_ctx);
 
-static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
-{
-	struct vring_virtqueue *vq = to_vvq(_vq);
-	u16 new, old;
-	bool needs_kick;
-
-	START_USE(vq);
-	/* We need to expose available array entries before checking avail
-	 * event. */
-	virtio_mb(vq->weak_barriers);
-
-	old = vq->avail_idx_shadow - vq->num_added;
-	new = vq->avail_idx_shadow;
-	vq->num_added = 0;
-
-#ifdef DEBUG
-	if (vq->last_add_time_valid) {
-		WARN_ON(ktime_to_ms(ktime_sub(ktime_get(),
-					      vq->last_add_time)) > 100);
-	}
-	vq->last_add_time_valid = false;
-#endif
-
-	if (vq->event) {
-		needs_kick = vring_need_event(virtio16_to_cpu(_vq->vdev, vring_avail_event(&vq->vring)),
-					      new, old);
-	} else {
-		needs_kick = !(vq->vring.used->flags & cpu_to_virtio16(_vq->vdev, VRING_USED_F_NO_NOTIFY));
-	}
-	END_USE(vq);
-	return needs_kick;
-}
-
 /**
  * virtqueue_kick_prepare - first half of split virtqueue_kick call.
  * @vq: the struct virtqueue
@@ -644,118 +872,6 @@ bool virtqueue_kick(struct virtqueue *vq)
 }
 EXPORT_SYMBOL_GPL(virtqueue_kick);
 
-static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
-			     void **ctx)
-{
-	unsigned int i, j;
-	__virtio16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
-
-	/* Clear data ptr. */
-	vq->desc_state[head].data = NULL;
-
-	/* Put back on free list: unmap first-level descriptors and find end */
-	i = head;
-
-	while (vq->vring.desc[i].flags & nextflag) {
-		vring_unmap_one_split(vq, &vq->vring.desc[i]);
-		i = virtio16_to_cpu(vq->vq.vdev, vq->vring.desc[i].next);
-		vq->vq.num_free++;
-	}
-
-	vring_unmap_one_split(vq, &vq->vring.desc[i]);
-	vq->vring.desc[i].next = cpu_to_virtio16(vq->vq.vdev, vq->free_head);
-	vq->free_head = head;
-
-	/* Plus final descriptor */
-	vq->vq.num_free++;
-
-	if (vq->indirect) {
-		struct vring_desc *indir_desc = vq->desc_state[head].indir_desc;
-		u32 len;
-
-		/* Free the indirect table, if any, now that it's unmapped. */
-		if (!indir_desc)
-			return;
-
-		len = virtio32_to_cpu(vq->vq.vdev, vq->vring.desc[head].len);
-
-		BUG_ON(!(vq->vring.desc[head].flags &
-			 cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT)));
-		BUG_ON(len == 0 || len % sizeof(struct vring_desc));
-
-		for (j = 0; j < len / sizeof(struct vring_desc); j++)
-			vring_unmap_one_split(vq, &indir_desc[j]);
-
-		kfree(indir_desc);
-		vq->desc_state[head].indir_desc = NULL;
-	} else if (ctx) {
-		*ctx = vq->desc_state[head].indir_desc;
-	}
-}
-
-static inline bool more_used_split(const struct vring_virtqueue *vq)
-{
-	return vq->last_used_idx != virtio16_to_cpu(vq->vq.vdev, vq->vring.used->idx);
-}
-
-static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
-					 unsigned int *len,
-					 void **ctx)
-{
-	struct vring_virtqueue *vq = to_vvq(_vq);
-	void *ret;
-	unsigned int i;
-	u16 last_used;
-
-	START_USE(vq);
-
-	if (unlikely(vq->broken)) {
-		END_USE(vq);
-		return NULL;
-	}
-
-	if (!more_used_split(vq)) {
-		pr_debug("No more buffers in queue\n");
-		END_USE(vq);
-		return NULL;
-	}
-
-	/* Only get used array entries after they have been exposed by host. */
-	virtio_rmb(vq->weak_barriers);
-
-	last_used = (vq->last_used_idx & (vq->vring.num - 1));
-	i = virtio32_to_cpu(_vq->vdev, vq->vring.used->ring[last_used].id);
-	*len = virtio32_to_cpu(_vq->vdev, vq->vring.used->ring[last_used].len);
-
-	if (unlikely(i >= vq->vring.num)) {
-		BAD_RING(vq, "id %u out of range\n", i);
-		return NULL;
-	}
-	if (unlikely(!vq->desc_state[i].data)) {
-		BAD_RING(vq, "id %u is not a head!\n", i);
-		return NULL;
-	}
-
-	/* detach_buf_split clears data, so grab it now. */
-	ret = vq->desc_state[i].data;
-	detach_buf_split(vq, i, ctx);
-	vq->last_used_idx++;
-	/* If we expect an interrupt for the next entry, tell host
-	 * by writing event index and flush out the write before
-	 * the read in the next get_buf call. */
-	if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
-		virtio_store_mb(vq->weak_barriers,
-				&vring_used_event(&vq->vring),
-				cpu_to_virtio16(_vq->vdev, vq->last_used_idx));
-
-#ifdef DEBUG
-	vq->last_add_time_valid = false;
-#endif
-
-	END_USE(vq);
-	return ret;
-}
-
 /**
  * virtqueue_get_buf - get the next used buffer
  * @vq: the struct virtqueue we're talking about.
@@ -785,17 +901,6 @@ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
 }
 EXPORT_SYMBOL_GPL(virtqueue_get_buf);
 
-static void virtqueue_disable_cb_split(struct virtqueue *_vq)
-{
-	struct vring_virtqueue *vq = to_vvq(_vq);
-
-	if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
-		vq->avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
-		if (!vq->event)
-			vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow);
-	}
-}
-
 /**
  * virtqueue_disable_cb - disable callbacks
  * @vq: the struct virtqueue we're talking about.
@@ -811,28 +916,6 @@ void virtqueue_disable_cb(struct virtqueue *_vq)
 }
 EXPORT_SYMBOL_GPL(virtqueue_disable_cb);
 
-static unsigned virtqueue_enable_cb_prepare_split(struct virtqueue *_vq)
-{
-	struct vring_virtqueue *vq = to_vvq(_vq);
-	u16 last_used_idx;
-
-	START_USE(vq);
-
-	/* We optimistically turn back on interrupts, then check if there was
-	 * more to do. */
-	/* Depending on the VIRTIO_RING_F_EVENT_IDX feature, we need to
-	 * either clear the flags bit or point the event index at the next
-	 * entry. Always do both to keep code simple. */
-	if (vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
-		vq->avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
-		if (!vq->event)
-			vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow);
-	}
-	vring_used_event(&vq->vring) = cpu_to_virtio16(_vq->vdev, last_used_idx = vq->last_used_idx);
-	END_USE(vq);
-	return last_used_idx;
-}
-
 /**
  * virtqueue_enable_cb_prepare - restart callbacks after disable_cb
  * @vq: the struct virtqueue we're talking about.
@@ -851,14 +934,6 @@ unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq)
 }
 EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare);
 
-static bool virtqueue_poll_split(struct virtqueue *_vq, unsigned last_used_idx)
-{
-	struct vring_virtqueue *vq = to_vvq(_vq);
-
-	return (u16)last_used_idx != virtio16_to_cpu(_vq->vdev,
-			vq->vring.used->idx);
-}
-
 /**
  * virtqueue_poll - query pending used buffers
  * @vq: the struct virtqueue we're talking about.
@@ -891,43 +966,11 @@ EXPORT_SYMBOL_GPL(virtqueue_poll);
 bool virtqueue_enable_cb(struct virtqueue *_vq)
 {
 	unsigned last_used_idx = virtqueue_enable_cb_prepare(_vq);
+
 	return !virtqueue_poll(_vq, last_used_idx);
 }
 EXPORT_SYMBOL_GPL(virtqueue_enable_cb);
 
-static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
-{
-	struct vring_virtqueue *vq = to_vvq(_vq);
-	u16 bufs;
-
-	START_USE(vq);
-
-	/* We optimistically turn back on interrupts, then check if there was
-	 * more to do. */
-	/* Depending on the VIRTIO_RING_F_USED_EVENT_IDX feature, we need to
-	 * either clear the flags bit or point the event index at the next
-	 * entry. Always update the event index to keep code simple. */
-	if (vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
-		vq->avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
-		if (!vq->event)
-			vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow);
-	}
-	/* TODO: tune this threshold */
-	bufs = (u16)(vq->avail_idx_shadow - vq->last_used_idx) * 3 / 4;
-
-	virtio_store_mb(vq->weak_barriers,
-			&vring_used_event(&vq->vring),
-			cpu_to_virtio16(_vq->vdev, vq->last_used_idx + bufs));
-
-	if (unlikely((u16)(virtio16_to_cpu(_vq->vdev, vq->vring.used->idx) - vq->last_used_idx) > bufs)) {
-		END_USE(vq);
-		return false;
-	}
-
-	END_USE(vq);
-	return true;
-}
-
 /**
  * virtqueue_enable_cb_delayed - restart callbacks after disable_cb.
  * @vq: the struct virtqueue we're talking about.
@@ -947,32 +990,6 @@ bool virtqueue_enable_cb_delayed(struct virtqueue *_vq)
 }
 EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed);
 
-static void *virtqueue_detach_unused_buf_split(struct virtqueue *_vq)
-{
-	struct vring_virtqueue *vq = to_vvq(_vq);
-	unsigned int i;
-	void *buf;
-
-	START_USE(vq);
-
-	for (i = 0; i < vq->vring.num; i++) {
-		if (!vq->desc_state[i].data)
-			continue;
-		/* detach_buf_split clears data, so grab it now. */
-		buf = vq->desc_state[i].data;
-		detach_buf_split(vq, i, NULL);
-		vq->avail_idx_shadow--;
-		vq->vring.avail->idx = cpu_to_virtio16(_vq->vdev, vq->avail_idx_shadow);
-		END_USE(vq);
-		return buf;
-	}
-	/* That should have freed everything. */
-	BUG_ON(vq->vq.num_free != vq->vring.num);
-
-	END_USE(vq);
-	return NULL;
-}
-
 /**
  * virtqueue_detach_unused_buf - detach first unused buffer
  * @vq: the struct virtqueue we're talking about.