Currently we have a problem with this: 1. i915: create gem object 2. i915: export gem object to prime 3. radeon: import gem object 4. close prime fd 5. radeon: unref object 6. i915: unref object
i915 has an imported object reference in its file priv, that isn't cleaned up properly until fd close. The reference gets added at step 2, but at step 6 we don't have enough info to clean it up.
The solution is to take a reference on the dma-buf when we export it, and drop the reference when the gem handle goes away.
So when we export a dma_buf from a gem object, we keep track of it with the handle, we take a reference to the dma_buf. When we close the handle (i.e. userspace is finished with the buffer), we drop the reference to the dma_buf, and it gets collected.
This patch isn't meant to fix any other problem or bikesheds, and it doesn't fix any races with other scenarios.
v1.1: move export symbol line back up.
v2: okay I had to do a bit more, as the first patch showed a leak on one of my tests, that I found using the dma-buf debugfs support, the problem case is exporting a buffer twice with the same handle, we'd add another export handle for it unnecessarily, however we now fail if we try to export the same object with a different gem handle, however I'm not sure if that is a case I want to support, and I've gotten the code to WARN_ON if we hit something like that.
v2.1: rebase this patch, write better commit msg.
Signed-off-by: Dave Airlie airlied@redhat.com --- drivers/gpu/drm/drm_gem.c | 2 +- drivers/gpu/drm/drm_prime.c | 94 ++++++++++++++++++++++++++++++++------------- include/drm/drmP.h | 3 +- 3 files changed, 71 insertions(+), 28 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index af779ae..f0f7a86 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -209,7 +209,7 @@ drm_gem_remove_prime_handles(struct drm_gem_object *obj, struct drm_file *filp) obj->import_attach->dmabuf); } if (obj->export_dma_buf) { - drm_prime_remove_imported_buf_handle(&filp->prime, + drm_prime_remove_exported_buf_handle(&filp->prime, obj->export_dma_buf); } } diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index 366910d..05ee250 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -157,6 +157,8 @@ static const struct dma_buf_ops drm_gem_prime_dmabuf_ops = { .vunmap = drm_gem_dmabuf_vunmap, };
+static int drm_prime_add_exported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t handle); + /** * DOC: PRIME Helpers * @@ -201,6 +203,8 @@ int drm_gem_prime_handle_to_fd(struct drm_device *dev, struct drm_gem_object *obj; void *buf; int ret; + struct dma_buf *dmabuf; + uint32_t exp_handle;
obj = drm_gem_object_lookup(dev, file_priv, handle); if (!obj) @@ -209,41 +213,52 @@ int drm_gem_prime_handle_to_fd(struct drm_device *dev, mutex_lock(&file_priv->prime.lock); /* re-export the original imported object */ if (obj->import_attach) { - get_dma_buf(obj->import_attach->dmabuf); - *prime_fd = dma_buf_fd(obj->import_attach->dmabuf, flags); - drm_gem_object_unreference_unlocked(obj); - mutex_unlock(&file_priv->prime.lock); - return 0; + dmabuf = obj->import_attach->dmabuf; + goto out_have_obj; }
if (obj->export_dma_buf) { - get_dma_buf(obj->export_dma_buf); - *prime_fd = dma_buf_fd(obj->export_dma_buf, flags); + dmabuf = obj->export_dma_buf; + goto out_have_obj; + } + + buf = dev->driver->gem_prime_export(dev, obj, flags); + if (IS_ERR(buf)) { + /* normally the created dma-buf takes ownership of the ref, + * but if that fails then drop the ref + */ drm_gem_object_unreference_unlocked(obj); - } else { - buf = dev->driver->gem_prime_export(dev, obj, flags); - if (IS_ERR(buf)) { - /* normally the created dma-buf takes ownership of the ref, - * but if that fails then drop the ref - */ - drm_gem_object_unreference_unlocked(obj); - mutex_unlock(&file_priv->prime.lock); - return PTR_ERR(buf); - } - obj->export_dma_buf = buf; - *prime_fd = dma_buf_fd(buf, flags); + mutex_unlock(&file_priv->prime.lock); + return PTR_ERR(buf); } + obj->export_dma_buf = buf; + /* if we've exported this buffer the cheat and add it to the import list * so we get the correct handle back */ - ret = drm_prime_add_imported_buf_handle(&file_priv->prime, - obj->export_dma_buf, handle); + ret = drm_prime_add_exported_buf_handle(&file_priv->prime, + obj->export_dma_buf, handle); if (ret) { drm_gem_object_unreference_unlocked(obj); mutex_unlock(&file_priv->prime.lock); return ret; } + *prime_fd = dma_buf_fd(buf, flags); + mutex_unlock(&file_priv->prime.lock); + return 0;
+out_have_obj: + get_dma_buf(dmabuf); + ret = drm_prime_lookup_buf_handle(&file_priv->prime, + dmabuf, &exp_handle); + if (WARN_ON(ret == -ENOENT || exp_handle != handle)) { + dma_buf_put(dmabuf); + drm_gem_object_unreference_unlocked(obj); + mutex_unlock(&file_priv->prime.lock); + return -EINVAL; + } + *prime_fd = dma_buf_fd(dmabuf, flags); + drm_gem_object_unreference_unlocked(obj); mutex_unlock(&file_priv->prime.lock); return 0; } @@ -314,7 +329,7 @@ int drm_gem_prime_fd_to_handle(struct drm_device *dev,
mutex_lock(&file_priv->prime.lock);
- ret = drm_prime_lookup_imported_buf_handle(&file_priv->prime, + ret = drm_prime_lookup_buf_handle(&file_priv->prime, dma_buf, handle); if (!ret) { ret = 0; @@ -491,7 +506,7 @@ void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv) } EXPORT_SYMBOL(drm_prime_destroy_file_private);
-int drm_prime_add_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t handle) +int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t handle) { struct drm_prime_member *member;
@@ -504,9 +519,21 @@ int drm_prime_add_imported_buf_handle(struct drm_prime_file_private *prime_fpriv list_add(&member->entry, &prime_fpriv->head); return 0; } + +int drm_prime_add_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t handle) +{ + return drm_prime_add_buf_handle(prime_fpriv, dma_buf, handle); +} EXPORT_SYMBOL(drm_prime_add_imported_buf_handle);
-int drm_prime_lookup_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t *handle) +static int drm_prime_add_exported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t handle) +{ + /* take a reference to the buf handle for this case */ + get_dma_buf(dma_buf); + return drm_prime_add_buf_handle(prime_fpriv, dma_buf, handle); +} + +int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t *handle) { struct drm_prime_member *member;
@@ -518,9 +545,9 @@ int drm_prime_lookup_imported_buf_handle(struct drm_prime_file_private *prime_fp } return -ENOENT; } -EXPORT_SYMBOL(drm_prime_lookup_imported_buf_handle); +EXPORT_SYMBOL(drm_prime_lookup_buf_handle);
-void drm_prime_remove_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf) +void drm_prime_remove_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf) { struct drm_prime_member *member, *safe;
@@ -533,4 +560,19 @@ void drm_prime_remove_imported_buf_handle(struct drm_prime_file_private *prime_f } mutex_unlock(&prime_fpriv->lock); } + +void drm_prime_remove_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf) +{ + return drm_prime_remove_buf_handle(prime_fpriv, dma_buf); +} EXPORT_SYMBOL(drm_prime_remove_imported_buf_handle); + +void drm_prime_remove_exported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf) +{ + drm_prime_remove_buf_handle(prime_fpriv, dma_buf); + dma_buf_put(dma_buf); +} +EXPORT_SYMBOL(drm_prime_remove_exported_buf_handle); + + + diff --git a/include/drm/drmP.h b/include/drm/drmP.h index 2d94d74..0466808 100644 --- a/include/drm/drmP.h +++ b/include/drm/drmP.h @@ -1594,8 +1594,9 @@ extern void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *s void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv); void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv); int drm_prime_add_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t handle); -int drm_prime_lookup_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t *handle); +int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t *handle); void drm_prime_remove_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf); +void drm_prime_remove_exported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf);
int drm_prime_add_dma_buf(struct drm_device *dev, struct drm_gem_object *obj); int drm_prime_lookup_obj(struct drm_device *dev, struct dma_buf *buf,