unimore/kernel-hacking-2024-linux-steffo
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drm/shmem-helper: Switch to reservation lock

Browse source 
Replace all drm-shmem locks with a GEM reservation lock. This makes locks
consistent with dma-buf locking convention where importers are responsible
for holding reservation lock for all operations performed over dma-bufs,
preventing deadlock between dma-buf importers and exporters.

Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230529223935.2672495-7-dmitry.osipenko@collabora.com
This commit is contained in:
Dmitry Osipenko 2023-05-30 01:39:35 +03:00
parent 8021fa16b7
commit 21aa27ddc5
6 changed files with 124 additions and 156 deletions
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226
drivers/gpu/drm/drm_gem_shmem_helper.c
View file

@ -88,8 +88,6 @@ __drm_gem_shmem_create(struct drm_device *dev, size_t size, bool private)
if (ret)
goto err_release;
mutex_init(&shmem->pages_lock);
mutex_init(&shmem->vmap_lock);
INIT_LIST_HEAD(&shmem->madv_list);
if (!private) {
@ -141,11 +139,13 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
{
struct drm_gem_object *obj = &shmem->base;
drm_WARN_ON(obj->dev, shmem->vmap_use_count);
if (obj->import_attach) {
drm_prime_gem_destroy(obj, shmem->sgt);
} else {
dma_resv_lock(shmem->base.resv, NULL);
drm_WARN_ON(obj->dev, shmem->vmap_use_count);
if (shmem->sgt) {
dma_unmap_sgtable(obj->dev->dev, shmem->sgt,
DMA_BIDIRECTIONAL, 0);
@ -154,22 +154,24 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
}
if (shmem->pages)
drm_gem_shmem_put_pages(shmem);
drm_WARN_ON(obj->dev, shmem->pages_use_count);
dma_resv_unlock(shmem->base.resv);
}
drm_WARN_ON(obj->dev, shmem->pages_use_count);
drm_gem_object_release(obj);
mutex_destroy(&shmem->pages_lock);
mutex_destroy(&shmem->vmap_lock);
kfree(shmem);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_free);
static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
{
struct drm_gem_object *obj = &shmem->base;
struct page **pages;
dma_resv_assert_held(shmem->base.resv);
if (shmem->pages_use_count++ > 0)
return 0;
@ -197,35 +199,16 @@ static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
}
/*
* drm_gem_shmem_get_pages - Allocate backing pages for a shmem GEM object
* drm_gem_shmem_put_pages - Decrease use count on the backing pages for a shmem GEM object
* @shmem: shmem GEM object
*
* This function makes sure that backing pages exists for the shmem GEM object
* and increases the use count.
*
* Returns:
* 0 on success or a negative error code on failure.
* This function decreases the use count and puts the backing pages when use drops to zero.
*/
int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
{
struct drm_gem_object *obj = &shmem->base;
int ret;
drm_WARN_ON(obj->dev, obj->import_attach);
ret = mutex_lock_interruptible(&shmem->pages_lock);
if (ret)
return ret;
ret = drm_gem_shmem_get_pages_locked(shmem);
mutex_unlock(&shmem->pages_lock);
return ret;
}
EXPORT_SYMBOL(drm_gem_shmem_get_pages);
static void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem)
{
struct drm_gem_object *obj = &shmem->base;
dma_resv_assert_held(shmem->base.resv);
if (drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count))
return;
@ -243,21 +226,26 @@ static void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem)
shmem->pages_mark_accessed_on_put);
shmem->pages = NULL;
}
/*
* drm_gem_shmem_put_pages - Decrease use count on the backing pages for a shmem GEM object
* @shmem: shmem GEM object
*
* This function decreases the use count and puts the backing pages when use drops to zero.
*/
void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
{
mutex_lock(&shmem->pages_lock);
drm_gem_shmem_put_pages_locked(shmem);
mutex_unlock(&shmem->pages_lock);
}
EXPORT_SYMBOL(drm_gem_shmem_put_pages);
static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
{
int ret;
dma_resv_assert_held(shmem->base.resv);
ret = drm_gem_shmem_get_pages(shmem);
return ret;
}
static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem)
{
dma_resv_assert_held(shmem->base.resv);
drm_gem_shmem_put_pages(shmem);
}
/**
* drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
* @shmem: shmem GEM object
@ -271,10 +259,17 @@ EXPORT_SYMBOL(drm_gem_shmem_put_pages);
int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem)
{
struct drm_gem_object *obj = &shmem->base;
int ret;
drm_WARN_ON(obj->dev, obj->import_attach);
return drm_gem_shmem_get_pages(shmem);
ret = dma_resv_lock_interruptible(shmem->base.resv, NULL);
if (ret)
return ret;
ret = drm_gem_shmem_pin_locked(shmem);
dma_resv_unlock(shmem->base.resv);
return ret;
}
EXPORT_SYMBOL(drm_gem_shmem_pin);
@ -291,12 +286,29 @@ void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem)
drm_WARN_ON(obj->dev, obj->import_attach);
drm_gem_shmem_put_pages(shmem);
dma_resv_lock(shmem->base.resv, NULL);
drm_gem_shmem_unpin_locked(shmem);
dma_resv_unlock(shmem->base.resv);
}
EXPORT_SYMBOL(drm_gem_shmem_unpin);
static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem,
struct iosys_map *map)
/*
* drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
* @shmem: shmem GEM object
* @map: Returns the kernel virtual address of the SHMEM GEM object's backing
* store.
*
* This function makes sure that a contiguous kernel virtual address mapping
* exists for the buffer backing the shmem GEM object. It hides the differences
* between dma-buf imported and natively allocated objects.
*
* Acquired mappings should be cleaned up by calling drm_gem_shmem_vunmap().
*
* Returns:
* 0 on success or a negative error code on failure.
*/
int drm_gem_shmem_vmap(struct drm_gem_shmem_object *shmem,
struct iosys_map *map)
{
struct drm_gem_object *obj = &shmem->base;
int ret = 0;
@ -312,6 +324,8 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem,
} else {
pgprot_t prot = PAGE_KERNEL;
dma_resv_assert_held(shmem->base.resv);
if (shmem->vmap_use_count++ > 0) {
iosys_map_set_vaddr(map, shmem->vaddr);
return 0;
@ -346,58 +360,8 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem,
return ret;
}
/*
* drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
* @shmem: shmem GEM object
* @map: Returns the kernel virtual address of the SHMEM GEM object's backing
* store.
*
* This function makes sure that a contiguous kernel virtual address mapping
* exists for the buffer backing the shmem GEM object. It hides the differences
* between dma-buf imported and natively allocated objects.
*
* Acquired mappings should be cleaned up by calling drm_gem_shmem_vunmap().
*
* Returns:
* 0 on success or a negative error code on failure.
*/
int drm_gem_shmem_vmap(struct drm_gem_shmem_object *shmem,
struct iosys_map *map)
{
int ret;
ret = mutex_lock_interruptible(&shmem->vmap_lock);
if (ret)
return ret;
ret = drm_gem_shmem_vmap_locked(shmem, map);
mutex_unlock(&shmem->vmap_lock);
return ret;
}
EXPORT_SYMBOL(drm_gem_shmem_vmap);
static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
struct iosys_map *map)
{
struct drm_gem_object *obj = &shmem->base;
if (obj->import_attach) {
dma_buf_vunmap(obj->import_attach->dmabuf, map);
} else {
if (drm_WARN_ON_ONCE(obj->dev, !shmem->vmap_use_count))
return;
if (--shmem->vmap_use_count > 0)
return;
vunmap(shmem->vaddr);
drm_gem_shmem_put_pages(shmem);
}
shmem->vaddr = NULL;
}
/*
* drm_gem_shmem_vunmap - Unmap a virtual mapping for a shmem GEM object
* @shmem: shmem GEM object
@ -413,9 +377,24 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
void drm_gem_shmem_vunmap(struct drm_gem_shmem_object *shmem,
struct iosys_map *map)
{
mutex_lock(&shmem->vmap_lock);
drm_gem_shmem_vunmap_locked(shmem, map);
mutex_unlock(&shmem->vmap_lock);
struct drm_gem_object *obj = &shmem->base;
if (obj->import_attach) {
dma_buf_vunmap(obj->import_attach->dmabuf, map);
} else {
dma_resv_assert_held(shmem->base.resv);
if (drm_WARN_ON_ONCE(obj->dev, !shmem->vmap_use_count))
return;
if (--shmem->vmap_use_count > 0)
return;
vunmap(shmem->vaddr);
drm_gem_shmem_put_pages(shmem);
}
shmem->vaddr = NULL;
}
EXPORT_SYMBOL(drm_gem_shmem_vunmap);
@ -447,24 +426,24 @@ drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
*/
int drm_gem_shmem_madvise(struct drm_gem_shmem_object *shmem, int madv)
{
mutex_lock(&shmem->pages_lock);
dma_resv_assert_held(shmem->base.resv);
if (shmem->madv >= 0)
shmem->madv = madv;
madv = shmem->madv;
mutex_unlock(&shmem->pages_lock);
return (madv >= 0);
}
EXPORT_SYMBOL(drm_gem_shmem_madvise);
void drm_gem_shmem_purge_locked(struct drm_gem_shmem_object *shmem)
void drm_gem_shmem_purge(struct drm_gem_shmem_object *shmem)
{
struct drm_gem_object *obj = &shmem->base;
struct drm_device *dev = obj->dev;
dma_resv_assert_held(shmem->base.resv);
drm_WARN_ON(obj->dev, !drm_gem_shmem_is_purgeable(shmem));
dma_unmap_sgtable(dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0);
@ -472,7 +451,7 @@ void drm_gem_shmem_purge_locked(struct drm_gem_shmem_object *shmem)
kfree(shmem->sgt);
shmem->sgt = NULL;
drm_gem_shmem_put_pages_locked(shmem);
drm_gem_shmem_put_pages(shmem);
shmem->madv = -1;
@ -488,17 +467,6 @@ void drm_gem_shmem_purge_locked(struct drm_gem_shmem_object *shmem)
invalidate_mapping_pages(file_inode(obj->filp)->i_mapping, 0, (loff_t)-1);
}
EXPORT_SYMBOL(drm_gem_shmem_purge_locked);
bool drm_gem_shmem_purge(struct drm_gem_shmem_object *shmem)
{
if (!mutex_trylock(&shmem->pages_lock))
return false;
drm_gem_shmem_purge_locked(shmem);
mutex_unlock(&shmem->pages_lock);
return true;
}
EXPORT_SYMBOL(drm_gem_shmem_purge);
/**
@ -551,7 +519,7 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
/* We don't use vmf->pgoff since that has the fake offset */
page_offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT;
mutex_lock(&shmem->pages_lock);
dma_resv_lock(shmem->base.resv, NULL);
if (page_offset >= num_pages ||
drm_WARN_ON_ONCE(obj->dev, !shmem->pages) ||
@ -563,7 +531,7 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
ret = vmf_insert_pfn(vma, vmf->address, page_to_pfn(page));
}
mutex_unlock(&shmem->pages_lock);
dma_resv_unlock(shmem->base.resv);
return ret;
}
@ -575,7 +543,7 @@ static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
drm_WARN_ON(obj->dev, obj->import_attach);
mutex_lock(&shmem->pages_lock);
dma_resv_lock(shmem->base.resv, NULL);
/*
* We should have already pinned the pages when the buffer was first
@ -585,7 +553,7 @@ static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
if (!drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count))
shmem->pages_use_count++;
mutex_unlock(&shmem->pages_lock);
dma_resv_unlock(shmem->base.resv);
drm_gem_vm_open(vma);
}
@ -595,7 +563,10 @@ static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
struct drm_gem_object *obj = vma->vm_private_data;
struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
dma_resv_lock(shmem->base.resv, NULL);
drm_gem_shmem_put_pages(shmem);
dma_resv_unlock(shmem->base.resv);
drm_gem_vm_close(vma);
}
@ -633,7 +604,10 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct
return ret;
}
dma_resv_lock(shmem->base.resv, NULL);
ret = drm_gem_shmem_get_pages(shmem);
dma_resv_unlock(shmem->base.resv);
if (ret)
return ret;
@ -699,7 +673,7 @@ static struct sg_table *drm_gem_shmem_get_pages_sgt_locked(struct drm_gem_shmem_
drm_WARN_ON(obj->dev, obj->import_attach);
ret = drm_gem_shmem_get_pages_locked(shmem);
ret = drm_gem_shmem_get_pages(shmem);
if (ret)
return ERR_PTR(ret);
@ -721,7 +695,7 @@ static struct sg_table *drm_gem_shmem_get_pages_sgt_locked(struct drm_gem_shmem_
sg_free_table(sgt);
kfree(sgt);
err_put_pages:
drm_gem_shmem_put_pages_locked(shmem);
drm_gem_shmem_put_pages(shmem);
return ERR_PTR(ret);
}
@ -746,11 +720,11 @@ 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);
ret = dma_resv_lock_interruptible(shmem->base.resv, NULL);
if (ret)
return ERR_PTR(ret);
sgt = drm_gem_shmem_get_pages_sgt_locked(shmem);
mutex_unlock(&shmem->pages_lock);
dma_resv_unlock(shmem->base.resv);
return sgt;
}

8
drivers/gpu/drm/lima/lima_gem.c
View file

@ -34,7 +34,7 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm)
new_size = min(new_size, bo->base.base.size);
mutex_lock(&bo->base.pages_lock);
dma_resv_lock(bo->base.base.resv, NULL);
if (bo->base.pages) {
pages = bo->base.pages;
@ -42,7 +42,7 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm)
pages = kvmalloc_array(bo->base.base.size >> PAGE_SHIFT,
sizeof(*pages), GFP_KERNEL | __GFP_ZERO);
if (!pages) {
mutex_unlock(&bo->base.pages_lock);
dma_resv_unlock(bo->base.base.resv);
return -ENOMEM;
}
@ -56,13 +56,13 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm)
struct page *page = shmem_read_mapping_page(mapping, i);
if (IS_ERR(page)) {
mutex_unlock(&bo->base.pages_lock);
dma_resv_unlock(bo->base.base.resv);
return PTR_ERR(page);
}
pages[i] = page;
}
mutex_unlock(&bo->base.pages_lock);
dma_resv_unlock(bo->base.base.resv);
ret = sg_alloc_table_from_pages(&sgt, pages, i, 0,
new_size, GFP_KERNEL);

7
drivers/gpu/drm/panfrost/panfrost_drv.c
View file

@ -407,6 +407,10 @@ static int panfrost_ioctl_madvise(struct drm_device *dev, void *data,
bo = to_panfrost_bo(gem_obj);
ret = dma_resv_lock_interruptible(bo->base.base.resv, NULL);
if (ret)
goto out_put_object;
mutex_lock(&pfdev->shrinker_lock);
mutex_lock(&bo->mappings.lock);
if (args->madv == PANFROST_MADV_DONTNEED) {
@ -444,7 +448,8 @@ static int panfrost_ioctl_madvise(struct drm_device *dev, void *data,
out_unlock_mappings:
mutex_unlock(&bo->mappings.lock);
mutex_unlock(&pfdev->shrinker_lock);
dma_resv_unlock(bo->base.base.resv);
out_put_object:
drm_gem_object_put(gem_obj);
return ret;
}

6
drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
View file

@ -48,14 +48,14 @@ static bool panfrost_gem_purge(struct drm_gem_object *obj)
if (!mutex_trylock(&bo->mappings.lock))
return false;
if (!mutex_trylock(&shmem->pages_lock))
if (!dma_resv_trylock(shmem->base.resv))
goto unlock_mappings;
panfrost_gem_teardown_mappings_locked(bo);
drm_gem_shmem_purge_locked(&bo->base);
drm_gem_shmem_purge(&bo->base);
ret = true;
mutex_unlock(&shmem->pages_lock);
dma_resv_unlock(shmem->base.resv);
unlock_mappings:
mutex_unlock(&bo->mappings.lock);

19
drivers/gpu/drm/panfrost/panfrost_mmu.c
View file

@ -443,6 +443,7 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
struct panfrost_gem_mapping *bomapping;
struct panfrost_gem_object *bo;
struct address_space *mapping;
struct drm_gem_object *obj;
pgoff_t page_offset;
struct sg_table *sgt;
struct page **pages;
@ -465,15 +466,16 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
page_offset = addr >> PAGE_SHIFT;
page_offset -= bomapping->mmnode.start;
mutex_lock(&bo->base.pages_lock);
obj = &bo->base.base;
dma_resv_lock(obj->resv, NULL);
if (!bo->base.pages) {
bo->sgts = kvmalloc_array(bo->base.base.size / SZ_2M,
sizeof(struct sg_table), GFP_KERNEL | __GFP_ZERO);
if (!bo->sgts) {
mutex_unlock(&bo->base.pages_lock);
ret = -ENOMEM;
goto err_bo;
goto err_unlock;
}
pages = kvmalloc_array(bo->base.base.size >> PAGE_SHIFT,
@ -481,9 +483,8 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
if (!pages) {
kvfree(bo->sgts);
bo->sgts = NULL;
mutex_unlock(&bo->base.pages_lock);
ret = -ENOMEM;
goto err_bo;
goto err_unlock;
}
bo->base.pages = pages;
bo->base.pages_use_count = 1;
@ -491,7 +492,6 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
pages = bo->base.pages;
if (pages[page_offset]) {
/* Pages are already mapped, bail out. */
mutex_unlock(&bo->base.pages_lock);
goto out;
}
}
@ -502,15 +502,12 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
for (i = page_offset; i < page_offset + NUM_FAULT_PAGES; i++) {
pages[i] = shmem_read_mapping_page(mapping, i);
if (IS_ERR(pages[i])) {
mutex_unlock(&bo->base.pages_lock);
ret = PTR_ERR(pages[i]);
pages[i] = NULL;
goto err_pages;
}
}
mutex_unlock(&bo->base.pages_lock);
sgt = &bo->sgts[page_offset / (SZ_2M / PAGE_SIZE)];
ret = sg_alloc_table_from_pages(sgt, pages + page_offset,
NUM_FAULT_PAGES, 0, SZ_2M, GFP_KERNEL);
@ -529,6 +526,8 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
dev_dbg(pfdev->dev, "mapped page fault @ AS%d %llx", as, addr);
out:
dma_resv_unlock(obj->resv);
panfrost_gem_mapping_put(bomapping);
return 0;
@ -537,6 +536,8 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
sg_free_table(sgt);
err_pages:
drm_gem_shmem_put_pages(&bo->base);
err_unlock:
dma_resv_unlock(obj->resv);
err_bo:
panfrost_gem_mapping_put(bomapping);
return ret;

14
include/drm/drm_gem_shmem_helper.h
View file

@ -26,11 +26,6 @@ struct drm_gem_shmem_object {
*/
struct drm_gem_object base;
/**
* @pages_lock: Protects the page table and use count
*/
struct mutex pages_lock;
/**
* @pages: Page table
*/
@ -65,11 +60,6 @@ struct drm_gem_shmem_object {
*/
struct sg_table *sgt;
/**
* @vmap_lock: Protects the vmap address and use count
*/
struct mutex vmap_lock;
/**
* @vaddr: Kernel virtual address of the backing memory
*/
@ -109,7 +99,6 @@ struct drm_gem_shmem_object {
struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t size);
void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem);
int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem);
void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem);
int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem);
void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem);
@ -128,8 +117,7 @@ static inline bool drm_gem_shmem_is_purgeable(struct drm_gem_shmem_object *shmem
!shmem->base.dma_buf && !shmem->base.import_attach;
}
void drm_gem_shmem_purge_locked(struct drm_gem_shmem_object *shmem);
bool drm_gem_shmem_purge(struct drm_gem_shmem_object *shmem);
void drm_gem_shmem_purge(struct drm_gem_shmem_object *shmem);
struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_shmem_object *shmem);
struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem);