[v1,5/7] Revert "drm: Assert held reservation lock for dma-buf mmapping"
Commit Message
Don't assert held dma-buf reservation lock on memory mapping of exported
buffer.
We're going to change dma-buf mmap() locking policy such that exporters
will have to handle the lock. The previous locking policy caused deadlock
problem for DRM drivers in a case of self-imported dma-bufs, it's solved
by moving the lock down to exporters.
Fixes: 39ce25291871 ("drm: Assert held reservation lock for dma-buf mmapping")
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
---
drivers/gpu/drm/drm_prime.c | 2 --
drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 2 --
drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c | 2 --
drivers/gpu/drm/tegra/gem.c | 2 --
4 files changed, 8 deletions(-)
Comments
Am 02.04.23 um 18:48 schrieb Dmitry Osipenko:
> Don't assert held dma-buf reservation lock on memory mapping of exported
> buffer.
>
> We're going to change dma-buf mmap() locking policy such that exporters
> will have to handle the lock. The previous locking policy caused deadlock
> problem for DRM drivers in a case of self-imported dma-bufs, it's solved
> by moving the lock down to exporters.
I only checked the TTM code path and think that at least that one should
work fine.
> Fixes: 39ce25291871 ("drm: Assert held reservation lock for dma-buf mmapping")
This here is not really a "fix" for the previous patch. We just found
that we didn't like the behavior and so reverted the original patch.
A "Reverts..." comment in the commit message would be more appropriate I
think.
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Acked-by: Christian König <christian.koenig@amd.com>
Regards,
Christian.
> ---
> drivers/gpu/drm/drm_prime.c | 2 --
> drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 2 --
> drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c | 2 --
> drivers/gpu/drm/tegra/gem.c | 2 --
> 4 files changed, 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index 149cd4ff6a3b..cea85e84666f 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -781,8 +781,6 @@ int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
> struct drm_gem_object *obj = dma_buf->priv;
> struct drm_device *dev = obj->dev;
>
> - dma_resv_assert_held(dma_buf->resv);
> -
> if (!dev->driver->gem_prime_mmap)
> return -ENOSYS;
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
> index fd556a076d05..1df74f7aa3dc 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
> @@ -97,8 +97,6 @@ static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *
> struct drm_i915_private *i915 = to_i915(obj->base.dev);
> int ret;
>
> - dma_resv_assert_held(dma_buf->resv);
> -
> if (obj->base.size < vma->vm_end - vma->vm_start)
> return -EINVAL;
>
> diff --git a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
> index 3abc47521b2c..8e194dbc9506 100644
> --- a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
> +++ b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
> @@ -66,8 +66,6 @@ static int omap_gem_dmabuf_mmap(struct dma_buf *buffer,
> struct drm_gem_object *obj = buffer->priv;
> int ret = 0;
>
> - dma_resv_assert_held(buffer->resv);
> -
> ret = drm_gem_mmap_obj(obj, omap_gem_mmap_size(obj), vma);
> if (ret < 0)
> return ret;
> diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c
> index bce991a2ccc0..871ef5d26523 100644
> --- a/drivers/gpu/drm/tegra/gem.c
> +++ b/drivers/gpu/drm/tegra/gem.c
> @@ -693,8 +693,6 @@ static int tegra_gem_prime_mmap(struct dma_buf *buf, struct vm_area_struct *vma)
> struct drm_gem_object *gem = buf->priv;
> int err;
>
> - dma_resv_assert_held(buf->resv);
> -
> err = drm_gem_mmap_obj(gem, gem->size, vma);
> if (err < 0)
> return err;
On 4/3/23 18:17, Christian König wrote:
> Am 02.04.23 um 18:48 schrieb Dmitry Osipenko:
>> Don't assert held dma-buf reservation lock on memory mapping of exported
>> buffer.
>>
>> We're going to change dma-buf mmap() locking policy such that exporters
>> will have to handle the lock. The previous locking policy caused deadlock
>> problem for DRM drivers in a case of self-imported dma-bufs, it's solved
>> by moving the lock down to exporters.
>
> I only checked the TTM code path and think that at least that one should
> work fine.
>
>> Fixes: 39ce25291871 ("drm: Assert held reservation lock for dma-buf
>> mmapping")
>
> This here is not really a "fix" for the previous patch. We just found
> that we didn't like the behavior and so reverted the original patch.
>
> A "Reverts..." comment in the commit message would be more appropriate I
> think.
Ack, will drop the fixes tag in v2. Thank you and Emil for the review.
@@ -781,8 +781,6 @@ int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
struct drm_gem_object *obj = dma_buf->priv;
struct drm_device *dev = obj->dev;
- dma_resv_assert_held(dma_buf->resv);
-
if (!dev->driver->gem_prime_mmap)
return -ENOSYS;
@@ -97,8 +97,6 @@ static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *
struct drm_i915_private *i915 = to_i915(obj->base.dev);
int ret;
- dma_resv_assert_held(dma_buf->resv);
-
if (obj->base.size < vma->vm_end - vma->vm_start)
return -EINVAL;
@@ -66,8 +66,6 @@ static int omap_gem_dmabuf_mmap(struct dma_buf *buffer,
struct drm_gem_object *obj = buffer->priv;
int ret = 0;
- dma_resv_assert_held(buffer->resv);
-
ret = drm_gem_mmap_obj(obj, omap_gem_mmap_size(obj), vma);
if (ret < 0)
return ret;
@@ -693,8 +693,6 @@ static int tegra_gem_prime_mmap(struct dma_buf *buf, struct vm_area_struct *vma)
struct drm_gem_object *gem = buf->priv;
int err;
- dma_resv_assert_held(buf->resv);
-
err = drm_gem_mmap_obj(gem, gem->size, vma);
if (err < 0)
return err;