Linux Virtualization - Mar 2023 - [PATCH 1/3] virtio_pci_modern: Remove unnecessary num zero check

This patch series performs a clean up of the code in virtio_ring and
virtio_pci, modifying it to conform with the Linux kernel coding style
guidance [1]. The modifications ensure the code easy to read and
understand. This small series does few short cleanups in the code.

Patch-1 Remove unnecessary num zero check, which performs in power_of_2.
Patch-2 Avoid using inline for small functions.
Patch-3 Use const to annotate read-only pointer params.

[1]
https://www.kernel.org/doc/html/v6.2-rc3/process/coding-style.html#the-inline-disease

Feng Liu (3):
  virtio_pci_modern: Remove unnecessary num zero check
  virtio_ring: Avoid using inline for small functions
  virtio_ring: Use const to annotate read-only pointer params

 drivers/virtio/virtio_pci_modern.c |  4 ++--
 drivers/virtio/virtio_ring.c       | 35 +++++++++++++++---------------
 include/linux/virtio.h             | 12 +++++-----
 3 files changed, 25 insertions(+), 26 deletions(-)

-- 
2.34.1

is_power_of_2() already performs the zero check. Hence avoid duplicate
check. While at it, move the query of size check also adjacent to where
its used for the disabled vq.

Signed-off-by: Feng Liu <feliu at nvidia.com>
Reviewed-by: Jiri Pirko <jiri at nvidia.com>
Reviewed-by: Parav Pandit <parav at nvidia.com>
Reviewed-by: Gavin Li <gavinl at nvidia.com>
Reviewed-by: Bodong Wang <bodong at nvidia.com>
---
 drivers/virtio/virtio_pci_modern.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_pci_modern.c
b/drivers/virtio/virtio_pci_modern.c
index 9e496e288cfa..3d7144f8f959 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -306,10 +306,10 @@ static struct virtqueue *setup_vq(struct virtio_pci_device
*vp_dev,
 		return ERR_PTR(-EINVAL);
 
 	/* Check if queue is either not available or already active. */
-	num = vp_modern_get_queue_size(mdev, index);
-	if (!num || vp_modern_get_queue_enable(mdev, index))
+	if (vp_modern_get_queue_enable(mdev, index))
 		return ERR_PTR(-ENOENT);
 
+	num = vp_modern_get_queue_size(mdev, index);
 	if (!is_power_of_2(num)) {
 		dev_warn(&vp_dev->pci_dev->dev, "bad queue size %u",
num);
 		return ERR_PTR(-EINVAL);
-- 
2.34.1

According to kernel coding style [1], defining inline functions is not
necessary and beneficial for simple functions. Hence clean up the code
by removing the inline keyword.

It is verified with GCC 12.2.0, the generated code with/without inline
is same. Additionally tested with pktgen and iperf, and verified the
result, the pps test results are the same in the cases of with/without
inline.

Iperf and pps of pktgen for virtio-net didn't change before and after
the change.

[1]
https://www.kernel.org/doc/html/v6.2-rc3/process/coding-style.html#the-inline-disease

Signed-off-by: Feng Liu <feliu at nvidia.com>
Reviewed-by: Jiri Pirko <jiri at nvidia.com>
Reviewed-by: Parav Pandit <parav at nvidia.com>
Reviewed-by: Gavin Li <gavinl at nvidia.com>
Reviewed-by: Bodong Wang <bodong at nvidia.com>
---
 drivers/virtio/virtio_ring.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 41144b5246a8..806cc44eae64 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -233,7 +233,7 @@ static void vring_free(struct virtqueue *_vq);
 
 #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
 
-static inline bool virtqueue_use_indirect(struct vring_virtqueue *vq,
+static bool virtqueue_use_indirect(struct vring_virtqueue *vq,
 					  unsigned int total_sg)
 {
 	/*
@@ -349,7 +349,7 @@ static void vring_free_queue(struct virtio_device *vdev,
size_t size,
  * making all of the arch DMA ops work on the vring device itself
  * is a mess.
  */
-static inline struct device *vring_dma_dev(const struct vring_virtqueue *vq)
+static struct device *vring_dma_dev(const struct vring_virtqueue *vq)
 {
 	return vq->dma_dev;
 }
@@ -784,7 +784,7 @@ static void detach_buf_split(struct vring_virtqueue *vq,
unsigned int head,
 	}
 }
 
-static inline bool more_used_split(const struct vring_virtqueue *vq)
+static inline more_used_split(const struct vring_virtqueue *vq)
 {
 	return vq->last_used_idx != virtio16_to_cpu(vq->vq.vdev,
 			vq->split.vring.used->idx);
@@ -1172,12 +1172,12 @@ static int virtqueue_resize_split(struct virtqueue *_vq,
u32 num)
 /*
  * Packed ring specific functions - *_packed().
  */
-static inline bool packed_used_wrap_counter(u16 last_used_idx)
+static bool packed_used_wrap_counter(u16 last_used_idx)
 {
 	return !!(last_used_idx & (1 << VRING_PACKED_EVENT_F_WRAP_CTR));
 }
 
-static inline u16 packed_last_used(u16 last_used_idx)
+static u16 packed_last_used(u16 last_used_idx)
 {
 	return last_used_idx & ~(-(1 << VRING_PACKED_EVENT_F_WRAP_CTR));
 }
@@ -1612,7 +1612,7 @@ static inline bool is_used_desc_packed(const struct
vring_virtqueue *vq,
 	return avail == used && used == used_wrap_counter;
 }
 
-static inline bool more_used_packed(const struct vring_virtqueue *vq)
+static bool more_used_packed(const struct vring_virtqueue *vq)
 {
 	u16 last_used;
 	u16 last_used_idx;
-- 
2.34.1

Add const to make the read-only pointer parameters clear, similar to
many existing functions.

Signed-off-by: Feng Liu <feliu at nvidia.com>
Reviewed-by: Jiri Pirko <jiri at nvidia.com>
Reviewed-by: Parav Pandit <parav at nvidia.com>
Reviewed-by: Gavin Li <gavinl at nvidia.com>
Reviewed-by: Bodong Wang <bodong at nvidia.com>
---
 drivers/virtio/virtio_ring.c | 25 ++++++++++++-------------
 include/linux/virtio.h       | 12 ++++++------
 2 files changed, 18 insertions(+), 19 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 806cc44eae64..8010fd1d2047 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -233,7 +233,7 @@ static void vring_free(struct virtqueue *_vq);
 
 #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
 
-static bool virtqueue_use_indirect(struct vring_virtqueue *vq,
+static bool virtqueue_use_indirect(const struct vring_virtqueue *vq,
 					  unsigned int total_sg)
 {
 	/*
@@ -269,7 +269,7 @@ static bool virtqueue_use_indirect(struct vring_virtqueue
*vq,
  * unconditionally on data path.
  */
 
-static bool vring_use_dma_api(struct virtio_device *vdev)
+static bool vring_use_dma_api(const struct virtio_device *vdev)
 {
 	if (!virtio_has_dma_quirk(vdev))
 		return true;
@@ -289,7 +289,7 @@ static bool vring_use_dma_api(struct virtio_device *vdev)
 	return false;
 }
 
-size_t virtio_max_dma_size(struct virtio_device *vdev)
+size_t virtio_max_dma_size(const struct virtio_device *vdev)
 {
 	size_t max_segment_size = SIZE_MAX;
 
@@ -423,7 +423,7 @@ static void virtqueue_init(struct vring_virtqueue *vq, u32
num)
  */
 
 static void vring_unmap_one_split_indirect(const struct vring_virtqueue *vq,
-					   struct vring_desc *desc)
+					   const struct vring_desc *desc)
 {
 	u16 flags;
 
@@ -1183,7 +1183,7 @@ static u16 packed_last_used(u16 last_used_idx)
 }
 
 static void vring_unmap_extra_packed(const struct vring_virtqueue *vq,
-				     struct vring_desc_extra *extra)
+				     const struct vring_desc_extra *extra)
 {
 	u16 flags;
 
@@ -1206,7 +1206,7 @@ static void vring_unmap_extra_packed(const struct
vring_virtqueue *vq,
 }
 
 static void vring_unmap_desc_packed(const struct vring_virtqueue *vq,
-				   struct vring_packed_desc *desc)
+				    const struct vring_packed_desc *desc)
 {
 	u16 flags;
 
@@ -2786,7 +2786,7 @@ EXPORT_SYMBOL_GPL(vring_transport_features);
  * Returns the size of the vring.  This is mainly used for boasting to
  * userspace.  Unlike other operations, this need not be serialized.
  */
-unsigned int virtqueue_get_vring_size(struct virtqueue *_vq)
+unsigned int virtqueue_get_vring_size(const struct virtqueue *_vq)
 {
 
 	struct vring_virtqueue *vq = to_vvq(_vq);
@@ -2819,7 +2819,7 @@ void __virtqueue_unbreak(struct virtqueue *_vq)
 }
 EXPORT_SYMBOL_GPL(__virtqueue_unbreak);
 
-bool virtqueue_is_broken(struct virtqueue *_vq)
+bool virtqueue_is_broken(const struct virtqueue *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
@@ -2827,8 +2827,7 @@ bool virtqueue_is_broken(struct virtqueue *_vq)
 }
 EXPORT_SYMBOL_GPL(virtqueue_is_broken);
 
-/*
- * This should prevent the device from being used, allowing drivers to
+/ This should prevent the device from being used, allowing drivers to
  * recover.  You may need to grab appropriate locks to flush.
  */
 void virtio_break_device(struct virtio_device *dev)
@@ -2881,7 +2880,7 @@ dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
 }
 EXPORT_SYMBOL_GPL(virtqueue_get_desc_addr);
 
-dma_addr_t virtqueue_get_avail_addr(struct virtqueue *_vq)
+dma_addr_t virtqueue_get_avail_addr(const struct virtqueue *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
@@ -2895,7 +2894,7 @@ dma_addr_t virtqueue_get_avail_addr(struct virtqueue *_vq)
 }
 EXPORT_SYMBOL_GPL(virtqueue_get_avail_addr);
 
-dma_addr_t virtqueue_get_used_addr(struct virtqueue *_vq)
+dma_addr_t virtqueue_get_used_addr(const struct virtqueue *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
@@ -2910,7 +2909,7 @@ dma_addr_t virtqueue_get_used_addr(struct virtqueue *_vq)
 EXPORT_SYMBOL_GPL(virtqueue_get_used_addr);
 
 /* Only available for split ring */
-const struct vring *virtqueue_get_vring(struct virtqueue *vq)
+const struct vring *virtqueue_get_vring(const struct virtqueue *vq)
 {
 	return &to_vvq(vq)->split.vring;
 }
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 2b472514c49b..36a79374e735 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -84,14 +84,14 @@ bool virtqueue_enable_cb_delayed(struct virtqueue *vq);
 
 void *virtqueue_detach_unused_buf(struct virtqueue *vq);
 
-unsigned int virtqueue_get_vring_size(struct virtqueue *vq);
+unsigned int virtqueue_get_vring_size(const struct virtqueue *vq);
 
-bool virtqueue_is_broken(struct virtqueue *vq);
+bool virtqueue_is_broken(const struct virtqueue *vq);
 
-const struct vring *virtqueue_get_vring(struct virtqueue *vq);
-dma_addr_t virtqueue_get_desc_addr(struct virtqueue *vq);
-dma_addr_t virtqueue_get_avail_addr(struct virtqueue *vq);
-dma_addr_t virtqueue_get_used_addr(struct virtqueue *vq);
+const struct vring *virtqueue_get_vring(const struct virtqueue *vq);
+dma_addr_t virtqueue_get_desc_addr(const struct virtqueue *vq);
+dma_addr_t virtqueue_get_avail_addr(const struct virtqueue *vq);
+dma_addr_t virtqueue_get_used_addr(const struct virtqueue *vq);
 
 int virtqueue_resize(struct virtqueue *vq, u32 num,
 		     void (*recycle)(struct virtqueue *vq, void *buf));
-- 
2.34.1