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drm/shmem-helper: Fix locking for drm_gem_shmem_get_pages_sgt() 

Other functions touching shmem->sgt take the pages lock, so do that here
too. drm_gem_shmem_get_pages() & co take the same lock, so move to the
_locked() variants to avoid recursive locking.

Discovered while auditing locking to write the Rust abstractions.

Fixes: 2194a63a81 ("drm: Add library for shmem backed GEM objects")
Fixes: 4fa3d66f13 ("drm/shmem: Do dma_unmap_sg before purging pages")
Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230205125124.2260-1-lina@asahilina.net
(cherry picked from commit aa8c85affe)
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
This commit is contained in:
Asahi Lina 2023-02-05 21:51:24 +09:00 committed by Javier Martinez Canillas
parent 38b2d8efd0
commit ddddedaa0d
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GPG Key ID: C751E590D63F3D69
1 changed files with 34 additions and 20 deletions
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54
drivers/gpu/drm/drm_gem_shmem_helper.c
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@ -678,23 +678,7 @@ struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_shmem_object *shmem)
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
/**
* drm_gem_shmem_get_pages_sgt - Pin pages, dma map them, and return a
* scatter/gather table for a shmem GEM object.
* @shmem: shmem GEM object
*
* This function returns a scatter/gather table suitable for driver usage. If
* the sg table doesn't exist, the pages are pinned, dma-mapped, and a sg
* table created.
*
* This is the main function for drivers to get at backing storage, and it hides
* and difference between dma-buf imported and natively allocated objects.
* drm_gem_shmem_get_sg_table() should not be directly called by drivers.
*
* Returns:
* A pointer to the scatter/gather table of pinned pages or errno on failure.
*/
struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem)
static struct sg_table *drm_gem_shmem_get_pages_sgt_locked(struct drm_gem_shmem_object *shmem)
{
struct drm_gem_object *obj = &shmem->base;
int ret;
@ -705,7 +689,7 @@ struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem)
WARN_ON(obj->import_attach);
ret = drm_gem_shmem_get_pages(shmem);
ret = drm_gem_shmem_get_pages_locked(shmem);
if (ret)
return ERR_PTR(ret);
@ -727,10 +711,40 @@ err_free_sgt:
sg_free_table(sgt);
kfree(sgt);
err_put_pages:
drm_gem_shmem_put_pages(shmem);
drm_gem_shmem_put_pages_locked(shmem);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_get_pages_sgt);
/**
* drm_gem_shmem_get_pages_sgt - Pin pages, dma map them, and return a
* scatter/gather table for a shmem GEM object.
* @shmem: shmem GEM object
*
* This function returns a scatter/gather table suitable for driver usage. If
* the sg table doesn't exist, the pages are pinned, dma-mapped, and a sg
* table created.
*
* This is the main function for drivers to get at backing storage, and it hides
* and difference between dma-buf imported and natively allocated objects.
* drm_gem_shmem_get_sg_table() should not be directly called by drivers.
*
* Returns:
* A pointer to the scatter/gather table of pinned pages or errno on failure.
*/
struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem)
{
int ret;
struct sg_table *sgt;
ret = mutex_lock_interruptible(&shmem->pages_lock);
if (ret)
return ERR_PTR(ret);
sgt = drm_gem_shmem_get_pages_sgt_locked(shmem);
mutex_unlock(&shmem->pages_lock);
return sgt;
}
EXPORT_SYMBOL(drm_gem_shmem_get_pages_sgt);
/**
* drm_gem_shmem_prime_import_sg_table - Produce a shmem GEM object from