Commit a7802784 authored by Thomas Zimmermann's avatar Thomas Zimmermann
Browse files

drm/gem: Acquire reservation lock in drm_gem_{pin/unpin}() 



Acquire the buffer object's reservation lock in drm_gem_pin() and
remove locking the drivers' GEM callbacks where necessary. Same for
unpin().

DRM drivers and memory managers modified by this patch will now have
correct dma-buf locking semantics: the caller is responsible for
holding the reservation lock when calling the pin or unpin callback.

DRM drivers and memory managers that are not modified will now be
protected against concurent invocation of their pin and unpin callbacks.

PRIME does not implement struct dma_buf_ops.pin, which requires
the caller to hold the reservation lock. It does implement struct
dma_buf_ops.attach, which requires to callee to acquire the
reservation lock. The PRIME code uses drm_gem_pin(), so locks
are now taken as specified. Same for unpin and detach.

The patch harmonizes GEM pin and unpin to have non-interruptible
reservation locking across all drivers, as is already the case for
vmap and vunmap. This affects gem-shmem, gem-vram, loongson, qxl and
radeon.

Signed-off-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Reviewed-by: default avatarZack Rusin <zack.rusin@broadcom.com>
Reviewed-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> # virtio-gpu
Link: https://patchwork.freedesktop.org/patch/msgid/20240227113853.8464-10-tzimmermann@suse.de
parent 94567420

drivers/gpu/drm/drm_gem.c

+20 −2
Original line number Diff line number Diff line
@@ -1161,7 +1161,7 @@ void drm_gem_print_info(struct drm_printer *p, unsigned int indent, 
		obj->funcs->print_info(p, indent, obj);

}



int drm_gem_pin(struct drm_gem_object *obj)

int drm_gem_pin_locked(struct drm_gem_object *obj)

{

	if (obj->funcs->pin)

		return obj->funcs->pin(obj);
@@ -1169,12 +1169,30 @@ int drm_gem_pin(struct drm_gem_object *obj) 
	return 0;

}



void drm_gem_unpin(struct drm_gem_object *obj)

void drm_gem_unpin_locked(struct drm_gem_object *obj)

{

	if (obj->funcs->unpin)

		obj->funcs->unpin(obj);

}



int drm_gem_pin(struct drm_gem_object *obj)

{

	int ret;



	dma_resv_lock(obj->resv, NULL);

	ret = drm_gem_pin_locked(obj);

	dma_resv_unlock(obj->resv);



	return ret;

}



void drm_gem_unpin(struct drm_gem_object *obj)

{

	dma_resv_lock(obj->resv, NULL);

	drm_gem_unpin_locked(obj);

	dma_resv_unlock(obj->resv);

}



int drm_gem_vmap(struct drm_gem_object *obj, struct iosys_map *map)

{

	int ret;

drivers/gpu/drm/drm_gem_vram_helper.c

+1 −14
Original line number Diff line number Diff line
@@ -774,11 +774,6 @@ EXPORT_SYMBOL(drm_gem_vram_simple_display_pipe_cleanup_fb); 
static int drm_gem_vram_object_pin(struct drm_gem_object *gem)

{

	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);

	int ret;



	ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);

	if (ret)

		return ret;



	/*

	 * Fbdev console emulation is the use case of these PRIME
@@ -789,10 +784,7 @@ static int drm_gem_vram_object_pin(struct drm_gem_object *gem) 
	 * the buffer to be pinned to VRAM, implement a callback that

	 * sets the flags accordingly.

	 */

	ret = drm_gem_vram_pin_locked(gbo, 0);

	ttm_bo_unreserve(&gbo->bo);



	return ret;

	return drm_gem_vram_pin_locked(gbo, 0);

}



/**
@@ -803,13 +795,8 @@ static int drm_gem_vram_object_pin(struct drm_gem_object *gem) 
static void drm_gem_vram_object_unpin(struct drm_gem_object *gem)

{

	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);

	int ret;



	ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);

	if (ret)

		return;

	drm_gem_vram_unpin_locked(gbo);

	ttm_bo_unreserve(&gbo->bo);

}



/**

drivers/gpu/drm/drm_internal.h

+2 −0
Original line number Diff line number Diff line
@@ -173,6 +173,8 @@ void drm_gem_release(struct drm_device *dev, struct drm_file *file_private); 
void drm_gem_print_info(struct drm_printer *p, unsigned int indent,

			const struct drm_gem_object *obj);



int drm_gem_pin_locked(struct drm_gem_object *obj);

void drm_gem_unpin_locked(struct drm_gem_object *obj);

int drm_gem_pin(struct drm_gem_object *obj);

void drm_gem_unpin(struct drm_gem_object *obj);

int drm_gem_vmap(struct drm_gem_object *obj, struct iosys_map *map);

drivers/gpu/drm/loongson/lsdc_gem.c

+2 −11
Original line number Diff line number Diff line
@@ -19,33 +19,24 @@ static int lsdc_gem_prime_pin(struct drm_gem_object *obj) 
	struct lsdc_bo *lbo = gem_to_lsdc_bo(obj);

	int ret;



	ret = lsdc_bo_reserve(lbo);

	if (unlikely(ret))

		return ret;

	dma_resv_assert_held(obj->resv);



	ret = lsdc_bo_pin(lbo, LSDC_GEM_DOMAIN_GTT, NULL);

	if (likely(ret == 0))

		lbo->sharing_count++;



	lsdc_bo_unreserve(lbo);



	return ret;

}



static void lsdc_gem_prime_unpin(struct drm_gem_object *obj)

{

	struct lsdc_bo *lbo = gem_to_lsdc_bo(obj);

	int ret;



	ret = lsdc_bo_reserve(lbo);

	if (unlikely(ret))

		return;

	dma_resv_assert_held(obj->resv);



	lsdc_bo_unpin(lbo);

	if (lbo->sharing_count)

		lbo->sharing_count--;



	lsdc_bo_unreserve(lbo);

}



static struct sg_table *lsdc_gem_prime_get_sg_table(struct drm_gem_object *obj)

drivers/gpu/drm/msm/msm_gem_prime.c

+0 −4
Original line number Diff line number Diff line
@@ -53,11 +53,9 @@ int msm_gem_prime_pin(struct drm_gem_object *obj) 
	if (obj->import_attach)

		return 0;



	msm_gem_lock(obj);

	pages = msm_gem_pin_pages_locked(obj);

	if (IS_ERR(pages))

		ret = PTR_ERR(pages);

	msm_gem_unlock(obj);



	return ret;

}
@@ -67,7 +65,5 @@ void msm_gem_prime_unpin(struct drm_gem_object *obj) 
	if (obj->import_attach)

		return;



	msm_gem_lock(obj);

	msm_gem_unpin_pages_locked(obj);

	msm_gem_unlock(obj);

}