lkml.org 
[lkml]   [2011]   [Nov]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/5] virtio: support unlocked queue kick
Hi Christoph,

On Wed, Oct 05, 2011 at 03:54:05PM -0400, Christoph Hellwig wrote:
> Split virtqueue_kick to be able to do the actual notification outside the
> lock protecting the virtqueue. This patch was originally done by

Nitpick:

Until now, virtqueue_kick is called under lock, still so description
confuses me. It would be better to be [5/5].

> Stefan Hajnoczi, but I can't find the original one anymore and had to
> recreated it from memory. Pointers to the original or corrections for
> the commit message are welcome.
>
> Index: linux-2.6/drivers/virtio/virtio_ring.c
> ===================================================================
> --- linux-2.6.orig/drivers/virtio/virtio_ring.c 2011-09-15 15:28:55.891347016 +0200
> +++ linux-2.6/drivers/virtio/virtio_ring.c 2011-10-03 18:45:32.492738431 +0200
> @@ -237,9 +237,11 @@ add_head:
> }
> EXPORT_SYMBOL_GPL(virtqueue_add_buf_gfp);
>
> -void virtqueue_kick(struct virtqueue *_vq)
> +bool virtqueue_kick_prepare(struct virtqueue *_vq)
> {
> struct vring_virtqueue *vq = to_vvq(_vq);
> + bool need_kick = false;
> +
> u16 new, old;
> START_USE(vq);
> /* Descriptors and available array need to be set before we expose the
> @@ -253,15 +255,32 @@ void virtqueue_kick(struct virtqueue *_v
> /* Need to update avail index before checking if we should notify */
> virtio_mb();
>
> - if (vq->event ?
> - vring_need_event(vring_avail_event(&vq->vring), new, old) :
> - !(vq->vring.used->flags & VRING_USED_F_NO_NOTIFY))
> - /* Prod other side to tell it about changes. */
> - vq->notify(&vq->vq);
> -
> + if (vq->event) {
> + if (vring_need_event(vring_avail_event(&vq->vring), new, old))
> + need_kick = true;
> + } else {
> + if (!(vq->vring.used->flags & VRING_USED_F_NO_NOTIFY))
> + need_kick = true;
> + }
> END_USE(vq);
> + return need_kick;
> +}
> +EXPORT_SYMBOL_GPL(virtqueue_kick_prepare);
> +
> +void virtqueue_notify(struct virtqueue *_vq)
> +{
> + struct vring_virtqueue *vq = to_vvq(_vq);
> +
> + /* Prod other side to tell it about changes. */
> + vq->notify(_vq);
> +}
> +EXPORT_SYMBOL_GPL(virtqueue_notify);
> +
> +void virtqueue_kick(struct virtqueue *vq)
> +{
> + if (virtqueue_kick_prepare(vq))
> + virtqueue_notify(vq);
> }
> -EXPORT_SYMBOL_GPL(virtqueue_kick);

It should be exported for using other modules.

--
Kind regards,
Minchan Kim


\
 
 \ /
  Last update: 2011-11-03 07:47    [W:0.234 / U:0.092 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site