[PATCH 4/4] dma-buf: drop caching of sg_tables
Christian König
ckoenig.leichtzumerken at gmail.com
Tue Feb 18 14:12:52 UTC 2025
Am 17.02.25 um 17:28 schrieb Simona Vetter:
> On Tue, Feb 11, 2025 at 05:31:09PM +0100, Christian König wrote:
>> That was purely for the transition from static to dynamic dma-buf
>> handling and can be removed again now.
>>
>> Signed-off-by: Christian König <christian.koenig at amd.com>
> Yay!
>
> Might uncover some fun if people have meanwhile started to rely on this
> for perf or something. But we'll figure that out when it happens.
Yeah that was exactly the reason why I made this a separate patch and didn't mixed it into patch #3.
On the other hand I'm fine to keep it a bit longer if anybody complains.
Christian.
>
> Reviewed-by: Simona Vetter <simona.vetter at ffwll.ch>
>
>
>> ---
>> drivers/dma-buf/dma-buf.c | 34 --------------------------
>> drivers/dma-buf/udmabuf.c | 1 -
>> drivers/gpu/drm/drm_prime.c | 1 -
>> drivers/gpu/drm/virtio/virtgpu_prime.c | 1 -
>> include/linux/dma-buf.h | 13 ----------
>> 5 files changed, 50 deletions(-)
>>
>> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
>> index 357b94a3dbaa..35221c4ddbf5 100644
>> --- a/drivers/dma-buf/dma-buf.c
>> +++ b/drivers/dma-buf/dma-buf.c
>> @@ -636,10 +636,6 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
>> || !exp_info->ops->release))
>> return ERR_PTR(-EINVAL);
>>
>> - if (WARN_ON(exp_info->ops->cache_sgt_mapping &&
>> - (exp_info->ops->pin || exp_info->ops->unpin)))
>> - return ERR_PTR(-EINVAL);
>> -
>> if (WARN_ON(!exp_info->ops->pin != !exp_info->ops->unpin))
>> return ERR_PTR(-EINVAL);
>>
>> @@ -964,17 +960,7 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
>> return;
>>
>> dma_resv_lock(dmabuf->resv, NULL);
>> -
>> - if (attach->sgt) {
>> - mangle_sg_table(attach->sgt);
>> - attach->dmabuf->ops->unmap_dma_buf(attach, attach->sgt,
>> - attach->dir);
>> -
>> - if (dma_buf_pin_on_map(attach))
>> - dma_buf_unpin(attach);
>> - }
>> list_del(&attach->node);
>> -
>> dma_resv_unlock(dmabuf->resv);
>>
>> if (dmabuf->ops->detach)
>> @@ -1069,18 +1055,6 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
>>
>> dma_resv_assert_held(attach->dmabuf->resv);
>>
>> - if (attach->sgt) {
>> - /*
>> - * Two mappings with different directions for the same
>> - * attachment are not allowed.
>> - */
>> - if (attach->dir != direction &&
>> - attach->dir != DMA_BIDIRECTIONAL)
>> - return ERR_PTR(-EBUSY);
>> -
>> - return attach->sgt;
>> - }
>> -
>> if (dma_buf_pin_on_map(attach)) {
>> ret = attach->dmabuf->ops->pin(attach);
>> if (ret)
>> @@ -1105,11 +1079,6 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
>> }
>> mangle_sg_table(sg_table);
>>
>> - if (attach->dmabuf->ops->cache_sgt_mapping) {
>> - attach->sgt = sg_table;
>> - attach->dir = direction;
>> - }
>> -
>> #ifdef CONFIG_DMA_API_DEBUG
>> {
>> struct scatterlist *sg;
>> @@ -1190,9 +1159,6 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
>>
>> dma_resv_assert_held(attach->dmabuf->resv);
>>
>> - if (attach->sgt == sg_table)
>> - return;
>> -
>> mangle_sg_table(sg_table);
>> attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
>>
>> diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
>> index cc7398cc17d6..2fa2c9135eac 100644
>> --- a/drivers/dma-buf/udmabuf.c
>> +++ b/drivers/dma-buf/udmabuf.c
>> @@ -285,7 +285,6 @@ static int end_cpu_udmabuf(struct dma_buf *buf,
>> }
>>
>> static const struct dma_buf_ops udmabuf_ops = {
>> - .cache_sgt_mapping = true,
>> .map_dma_buf = map_udmabuf,
>> .unmap_dma_buf = unmap_udmabuf,
>> .release = release_udmabuf,
>> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
>> index 32a8781cfd67..c284f306d597 100644
>> --- a/drivers/gpu/drm/drm_prime.c
>> +++ b/drivers/gpu/drm/drm_prime.c
>> @@ -810,7 +810,6 @@ int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
>> EXPORT_SYMBOL(drm_gem_dmabuf_mmap);
>>
>> static const struct dma_buf_ops drm_gem_prime_dmabuf_ops = {
>> - .cache_sgt_mapping = true,
>> .attach = drm_gem_map_attach,
>> .detach = drm_gem_map_detach,
>> .map_dma_buf = drm_gem_map_dma_buf,
>> diff --git a/drivers/gpu/drm/virtio/virtgpu_prime.c b/drivers/gpu/drm/virtio/virtgpu_prime.c
>> index fe6a0b018571..c6f3be3cb914 100644
>> --- a/drivers/gpu/drm/virtio/virtgpu_prime.c
>> +++ b/drivers/gpu/drm/virtio/virtgpu_prime.c
>> @@ -75,7 +75,6 @@ static void virtgpu_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
>>
>> static const struct virtio_dma_buf_ops virtgpu_dmabuf_ops = {
>> .ops = {
>> - .cache_sgt_mapping = true,
>> .attach = virtio_dma_buf_attach,
>> .detach = drm_gem_map_detach,
>> .map_dma_buf = virtgpu_gem_map_dma_buf,
>> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
>> index c54ff2dda8cb..544f8f8c3f44 100644
>> --- a/include/linux/dma-buf.h
>> +++ b/include/linux/dma-buf.h
>> @@ -34,15 +34,6 @@ struct dma_buf_attachment;
>> * @vunmap: [optional] unmaps a vmap from the buffer
>> */
>> struct dma_buf_ops {
>> - /**
>> - * @cache_sgt_mapping:
>> - *
>> - * If true the framework will cache the first mapping made for each
>> - * attachment. This avoids creating mappings for attachments multiple
>> - * times.
>> - */
>> - bool cache_sgt_mapping;
>> -
>> /**
>> * @attach:
>> *
>> @@ -493,8 +484,6 @@ struct dma_buf_attach_ops {
>> * @dmabuf: buffer for this attachment.
>> * @dev: device attached to the buffer.
>> * @node: list of dma_buf_attachment, protected by dma_resv lock of the dmabuf.
>> - * @sgt: cached mapping.
>> - * @dir: direction of cached mapping.
>> * @peer2peer: true if the importer can handle peer resources without pages.
>> * @priv: exporter specific attachment data.
>> * @importer_ops: importer operations for this attachment, if provided
>> @@ -514,8 +503,6 @@ struct dma_buf_attachment {
>> struct dma_buf *dmabuf;
>> struct device *dev;
>> struct list_head node;
>> - struct sg_table *sgt;
>> - enum dma_data_direction dir;
>> bool peer2peer;
>> const struct dma_buf_attach_ops *importer_ops;
>> void *importer_priv;
>> --
>> 2.34.1
>>
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