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Message-ID: <20220607023646-mutt-send-email-mst@kernel.org>
Date: Tue, 7 Jun 2022 02:38:16 -0400
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Bo Liu <liubo03@...pur.com>
Cc: jasowang@...hat.com, virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] virtio_ring: remove unnecessary to_vvq call
On Mon, Jun 06, 2022 at 08:59:51PM -0400, Bo Liu wrote:
> In many functions, the parameter passed in is "_vq", which still call
> to_vvq() to get 'vq'. It can avoid unnecessary call of to_vvq() by directly
> passing in the parameter "vq".
>
> Signed-off-by: Bo Liu <liubo03@...pur.com>
What does the patch accomplish? Is the generated binary faster? smaller?
> ---
> drivers/virtio/virtio_ring.c | 100 ++++++++++++++---------------------
> 1 file changed, 41 insertions(+), 59 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 13a7348cedff..f82db59fdbdc 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -648,9 +648,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> return -ENOMEM;
> }
>
> -static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
> +static bool virtqueue_kick_prepare_split(struct vring_virtqueue *vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> u16 new, old;
> bool needs_kick;
>
> @@ -667,12 +666,12 @@ static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
> LAST_ADD_TIME_INVALID(vq);
>
> if (vq->event) {
> - needs_kick = vring_need_event(virtio16_to_cpu(_vq->vdev,
> + needs_kick = vring_need_event(virtio16_to_cpu(vq->vq.vdev,
> vring_avail_event(&vq->split.vring)),
> new, old);
> } else {
> needs_kick = !(vq->split.vring.used->flags &
> - cpu_to_virtio16(_vq->vdev,
> + cpu_to_virtio16(vq->vq.vdev,
> VRING_USED_F_NO_NOTIFY));
> }
> END_USE(vq);
> @@ -735,11 +734,10 @@ static inline bool more_used_split(const struct vring_virtqueue *vq)
> vq->split.vring.used->idx);
> }
>
> -static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
> +static void *virtqueue_get_buf_ctx_split(struct vring_virtqueue *vq,
> unsigned int *len,
> void **ctx)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> void *ret;
> unsigned int i;
> u16 last_used;
> @@ -761,9 +759,9 @@ static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
> virtio_rmb(vq->weak_barriers);
>
> last_used = (vq->last_used_idx & (vq->split.vring.num - 1));
> - i = virtio32_to_cpu(_vq->vdev,
> + i = virtio32_to_cpu(vq->vq.vdev,
> vq->split.vring.used->ring[last_used].id);
> - *len = virtio32_to_cpu(_vq->vdev,
> + *len = virtio32_to_cpu(vq->vq.vdev,
> vq->split.vring.used->ring[last_used].len);
>
> if (unlikely(i >= vq->split.vring.num)) {
> @@ -785,7 +783,7 @@ static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
> if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
> virtio_store_mb(vq->weak_barriers,
> &vring_used_event(&vq->split.vring),
> - cpu_to_virtio16(_vq->vdev, vq->last_used_idx));
> + cpu_to_virtio16(vq->vq.vdev, vq->last_used_idx));
>
> LAST_ADD_TIME_INVALID(vq);
>
> @@ -793,10 +791,8 @@ static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
> return ret;
> }
>
> -static void virtqueue_disable_cb_split(struct virtqueue *_vq)
> +static void virtqueue_disable_cb_split(struct vring_virtqueue *vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> -
> if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
> vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
> if (vq->event)
> @@ -804,14 +800,13 @@ static void virtqueue_disable_cb_split(struct virtqueue *_vq)
> vring_used_event(&vq->split.vring) = 0x0;
> else
> vq->split.vring.avail->flags =
> - cpu_to_virtio16(_vq->vdev,
> + cpu_to_virtio16(vq->vq.vdev,
> vq->split.avail_flags_shadow);
> }
> }
>
> -static unsigned int virtqueue_enable_cb_prepare_split(struct virtqueue *_vq)
> +static unsigned int virtqueue_enable_cb_prepare_split(struct vring_virtqueue *vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> u16 last_used_idx;
>
> START_USE(vq);
> @@ -825,26 +820,23 @@ static unsigned int virtqueue_enable_cb_prepare_split(struct virtqueue *_vq)
> vq->split.avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
> if (!vq->event)
> vq->split.vring.avail->flags =
> - cpu_to_virtio16(_vq->vdev,
> + cpu_to_virtio16(vq->vq.vdev,
> vq->split.avail_flags_shadow);
> }
> - vring_used_event(&vq->split.vring) = cpu_to_virtio16(_vq->vdev,
> + vring_used_event(&vq->split.vring) = cpu_to_virtio16(vq->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 int last_used_idx)
> +static bool virtqueue_poll_split(struct vring_virtqueue *vq, unsigned int last_used_idx)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> -
> - return (u16)last_used_idx != virtio16_to_cpu(_vq->vdev,
> + return (u16)last_used_idx != virtio16_to_cpu(vq->vq.vdev,
> vq->split.vring.used->idx);
> }
>
> -static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
> +static bool virtqueue_enable_cb_delayed_split(struct vring_virtqueue *vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> u16 bufs;
>
> START_USE(vq);
> @@ -858,7 +850,7 @@ static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
> vq->split.avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
> if (!vq->event)
> vq->split.vring.avail->flags =
> - cpu_to_virtio16(_vq->vdev,
> + cpu_to_virtio16(vq->vq.vdev,
> vq->split.avail_flags_shadow);
> }
> /* TODO: tune this threshold */
> @@ -866,9 +858,9 @@ static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
>
> virtio_store_mb(vq->weak_barriers,
> &vring_used_event(&vq->split.vring),
> - cpu_to_virtio16(_vq->vdev, vq->last_used_idx + bufs));
> + cpu_to_virtio16(vq->vq.vdev, vq->last_used_idx + bufs));
>
> - if (unlikely((u16)(virtio16_to_cpu(_vq->vdev, vq->split.vring.used->idx)
> + if (unlikely((u16)(virtio16_to_cpu(vq->vq.vdev, vq->split.vring.used->idx)
> - vq->last_used_idx) > bufs)) {
> END_USE(vq);
> return false;
> @@ -878,9 +870,8 @@ static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
> return true;
> }
>
> -static void *virtqueue_detach_unused_buf_split(struct virtqueue *_vq)
> +static void *virtqueue_detach_unused_buf_split(struct vring_virtqueue *vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> unsigned int i;
> void *buf;
>
> @@ -893,7 +884,7 @@ static void *virtqueue_detach_unused_buf_split(struct virtqueue *_vq)
> buf = vq->split.desc_state[i].data;
> detach_buf_split(vq, i, NULL);
> vq->split.avail_idx_shadow--;
> - vq->split.vring.avail->idx = cpu_to_virtio16(_vq->vdev,
> + vq->split.vring.avail->idx = cpu_to_virtio16(vq->vq.vdev,
> vq->split.avail_idx_shadow);
> END_USE(vq);
> return buf;
> @@ -1296,9 +1287,8 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
> return -EIO;
> }
>
> -static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq)
> +static bool virtqueue_kick_prepare_packed(struct vring_virtqueue *vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> u16 new, old, off_wrap, flags, wrap_counter, event_idx;
> bool needs_kick;
> union {
> @@ -1410,11 +1400,10 @@ static inline bool more_used_packed(const struct vring_virtqueue *vq)
> vq->packed.used_wrap_counter);
> }
>
> -static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
> +static void *virtqueue_get_buf_ctx_packed(struct vring_virtqueue *vq,
> unsigned int *len,
> void **ctx)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> u16 last_used, id;
> void *ret;
>
> @@ -1475,10 +1464,8 @@ static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
> return ret;
> }
>
> -static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
> +static void virtqueue_disable_cb_packed(struct vring_virtqueue *vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> -
> if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE) {
> vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
> vq->packed.vring.driver->flags =
> @@ -1486,10 +1473,8 @@ static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
> }
> }
>
> -static unsigned int virtqueue_enable_cb_prepare_packed(struct virtqueue *_vq)
> +static unsigned int virtqueue_enable_cb_prepare_packed(struct vring_virtqueue *vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> -
> START_USE(vq);
>
> /*
> @@ -1522,9 +1507,8 @@ static unsigned int virtqueue_enable_cb_prepare_packed(struct virtqueue *_vq)
> VRING_PACKED_EVENT_F_WRAP_CTR);
> }
>
> -static bool virtqueue_poll_packed(struct virtqueue *_vq, u16 off_wrap)
> +static bool virtqueue_poll_packed(struct vring_virtqueue *vq, u16 off_wrap)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> bool wrap_counter;
> u16 used_idx;
>
> @@ -1534,9 +1518,8 @@ static bool virtqueue_poll_packed(struct virtqueue *_vq, u16 off_wrap)
> return is_used_desc_packed(vq, used_idx, wrap_counter);
> }
>
> -static bool virtqueue_enable_cb_delayed_packed(struct virtqueue *_vq)
> +static bool virtqueue_enable_cb_delayed_packed(struct vring_virtqueue *vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> u16 used_idx, wrap_counter;
> u16 bufs;
>
> @@ -1593,9 +1576,8 @@ static bool virtqueue_enable_cb_delayed_packed(struct virtqueue *_vq)
> return true;
> }
>
> -static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq)
> +static void *virtqueue_detach_unused_buf_packed(struct vring_virtqueue *vq)
> {
> - struct vring_virtqueue *vq = to_vvq(_vq);
> unsigned int i;
> void *buf;
>
> @@ -1906,8 +1888,8 @@ bool virtqueue_kick_prepare(struct virtqueue *_vq)
> {
> struct vring_virtqueue *vq = to_vvq(_vq);
>
> - return vq->packed_ring ? virtqueue_kick_prepare_packed(_vq) :
> - virtqueue_kick_prepare_split(_vq);
> + return vq->packed_ring ? virtqueue_kick_prepare_packed(vq) :
> + virtqueue_kick_prepare_split(vq);
> }
> EXPORT_SYMBOL_GPL(virtqueue_kick_prepare);
>
> @@ -1977,8 +1959,8 @@ void *virtqueue_get_buf_ctx(struct virtqueue *_vq, unsigned int *len,
> {
> struct vring_virtqueue *vq = to_vvq(_vq);
>
> - return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, ctx) :
> - virtqueue_get_buf_ctx_split(_vq, len, ctx);
> + return vq->packed_ring ? virtqueue_get_buf_ctx_packed(vq, len, ctx) :
> + virtqueue_get_buf_ctx_split(vq, len, ctx);
> }
> EXPORT_SYMBOL_GPL(virtqueue_get_buf_ctx);
>
> @@ -2007,9 +1989,9 @@ void virtqueue_disable_cb(struct virtqueue *_vq)
> return;
>
> if (vq->packed_ring)
> - virtqueue_disable_cb_packed(_vq);
> + virtqueue_disable_cb_packed(vq);
> else
> - virtqueue_disable_cb_split(_vq);
> + virtqueue_disable_cb_split(vq);
> }
> EXPORT_SYMBOL_GPL(virtqueue_disable_cb);
>
> @@ -2032,8 +2014,8 @@ unsigned int virtqueue_enable_cb_prepare(struct virtqueue *_vq)
> if (vq->event_triggered)
> vq->event_triggered = false;
>
> - return vq->packed_ring ? virtqueue_enable_cb_prepare_packed(_vq) :
> - virtqueue_enable_cb_prepare_split(_vq);
> + return vq->packed_ring ? virtqueue_enable_cb_prepare_packed(vq) :
> + virtqueue_enable_cb_prepare_split(vq);
> }
> EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare);
>
> @@ -2054,8 +2036,8 @@ bool virtqueue_poll(struct virtqueue *_vq, unsigned int last_used_idx)
> return false;
>
> virtio_mb(vq->weak_barriers);
> - return vq->packed_ring ? virtqueue_poll_packed(_vq, last_used_idx) :
> - virtqueue_poll_split(_vq, last_used_idx);
> + return vq->packed_ring ? virtqueue_poll_packed(vq, last_used_idx) :
> + virtqueue_poll_split(vq, last_used_idx);
> }
> EXPORT_SYMBOL_GPL(virtqueue_poll);
>
> @@ -2098,8 +2080,8 @@ bool virtqueue_enable_cb_delayed(struct virtqueue *_vq)
> if (vq->event_triggered)
> vq->event_triggered = false;
>
> - return vq->packed_ring ? virtqueue_enable_cb_delayed_packed(_vq) :
> - virtqueue_enable_cb_delayed_split(_vq);
> + return vq->packed_ring ? virtqueue_enable_cb_delayed_packed(vq) :
> + virtqueue_enable_cb_delayed_split(vq);
> }
> EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed);
>
> @@ -2115,8 +2097,8 @@ void *virtqueue_detach_unused_buf(struct virtqueue *_vq)
> {
> struct vring_virtqueue *vq = to_vvq(_vq);
>
> - return vq->packed_ring ? virtqueue_detach_unused_buf_packed(_vq) :
> - virtqueue_detach_unused_buf_split(_vq);
> + return vq->packed_ring ? virtqueue_detach_unused_buf_packed(vq) :
> + virtqueue_detach_unused_buf_split(vq);
> }
> EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf);
>
> --
> 2.27.0
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