lkml.org 
[lkml]   [2019]   [Sep]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2] drm/virtio: Use vmalloc for command buffer allocations.
> +/* How many bytes left in this page. */
> +static unsigned int rest_of_page(void *data)
> +{
> + return PAGE_SIZE - offset_in_page(data);
> +}

Not needed.

> +/* Create sg_table from a vmalloc'd buffer. */
> +static struct sg_table *vmalloc_to_sgt(char *data, uint32_t size, int *sg_ents)
> +{
> + int nents, ret, s, i;
> + struct sg_table *sgt;
> + struct scatterlist *sg;
> + struct page *pg;
> +
> + *sg_ents = 0;
> +
> + sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
> + if (!sgt)
> + return NULL;
> +
> + nents = DIV_ROUND_UP(size, PAGE_SIZE) + 1;

Why +1?

> + ret = sg_alloc_table(sgt, nents, GFP_KERNEL);
> + if (ret) {
> + kfree(sgt);
> + return NULL;
> + }
> +
> + for_each_sg(sgt->sgl, sg, nents, i) {
> + pg = vmalloc_to_page(data);
> + if (!pg) {
> + sg_free_table(sgt);
> + kfree(sgt);
> + return NULL;
> + }
> +
> + s = rest_of_page(data);
> + if (s > size)
> + s = size;

vmalloc memory is page aligned, so:

s = min(PAGE_SIZE, size);

> + sg_set_page(sg, pg, s, offset_in_page(data));

Offset is always zero.

> +
> + size -= s;
> + data += s;
> + *sg_ents += 1;

sg_ents isn't used anywhere.

> +
> + if (size) {
> + sg_unmark_end(sg);
> + } else {
> + sg_mark_end(sg);
> + break;
> + }

That looks a bit strange. I guess you need only one of the two because
the other is the default?

> static int virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
> struct virtio_gpu_vbuffer *vbuf,
> struct virtio_gpu_ctrl_hdr *hdr,
> struct virtio_gpu_fence *fence)
> {
> struct virtqueue *vq = vgdev->ctrlq.vq;
> + struct scatterlist *vout = NULL, sg;
> + struct sg_table *sgt = NULL;
> int rc;
> + int outcnt = 0;
> +
> + if (vbuf->data_size) {
> + if (is_vmalloc_addr(vbuf->data_buf)) {
> + sgt = vmalloc_to_sgt(vbuf->data_buf, vbuf->data_size,
> + &outcnt);
> + if (!sgt)
> + return -ENOMEM;
> + vout = sgt->sgl;
> + } else {
> + sg_init_one(&sg, vbuf->data_buf, vbuf->data_size);
> + vout = &sg;
> + outcnt = 1;

outcnt must be set in both cases.

> +static int virtio_gpu_queue_ctrl_buffer(struct virtio_gpu_device *vgdev,
> + struct virtio_gpu_vbuffer *vbuf)
> +{
> + return virtio_gpu_queue_fenced_ctrl_buffer(vgdev, vbuf, NULL, NULL);
> +}

Changing virtio_gpu_queue_ctrl_buffer to call
virtio_gpu_queue_fenced_ctrl_buffer should be done in a separate patch.

cheers,
Gerd

\
 
 \ /
  Last update: 2019-09-06 07:19    [W:0.159 / U:0.980 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site