Merge tag 'drm-next-2022-05-25' of git://anongit.freedesktop.org/drm/drm

Pull drm updates from Dave Airlie:
 "Intel have enabled DG2 on certain SKUs for laptops, AMD has started
  some new GPU support, msm has user allocated VA controls

  dma-buf:
   - add dma_resv_replace_fences
   - add dma_resv_get_singleton
   - make dma_excl_fence private

  core:
   - EDID parser refactorings
   - switch drivers to drm_mode_copy/duplicate
   - DRM managed mutex initialization

  display-helper:
   - put HDMI, SCDC, HDCP, DSC and DP into new module

  gem:
   - rework fence handling

  ttm:
   - rework bulk move handling
   - add common debugfs for resource managers
   - convert to kvcalloc

  format helpers:
   - support monochrome formats
   - RGB888, RGB565 to XRGB8888 conversions

  fbdev:
   - cfb/sys_imageblit fixes
   - pagelist corruption fix
   - create offb platform device
   - deferred io improvements

  sysfb:
   - Kconfig rework
   - support for VESA mode selection

  bridge:
   - conversions to devm_drm_of_get_bridge
   - conversions to panel_bridge
   - analogix_dp - autosuspend support
   - it66121 - audio support
   - tc358767 - DSI to DPI support
   - icn6211 - PLL/I2C fixes, DT property
   - adv7611 - enable DRM_BRIDGE_OP_HPD
   - anx7625 - fill ELD if no monitor
   - dw_hdmi - add audio support
   - lontium LT9211 support, i.MXMP LDB
   - it6505: Kconfig fix, DPCD set power fix
   - adv7511 - CEC support for ADV7535

  panel:
   - ltk035c5444t, B133UAN01, NV3052C panel support
   - DataImage FG040346DSSWBG04 support
   - st7735r - DT bindings fix
   - ssd130x - fixes

  i915:
   - DG2 laptop PCI-IDs ("motherboard down")
   - Initial RPL-P PCI IDs
   - compute engine ABI
   - DG2 Tile4 support
   - DG2 CCS clear color compression support
   - DG2 render/media compression formats support
   - ATS-M platform info
   - RPL-S PCI IDs added
   - Bump ADL-P DMC version to v2.16
   - Support static DRRS
   - Support multiple eDP/LVDS native mode refresh rates
   - DP HDR support for HSW+
   - Lots of display refactoring + fixes
   - GuC hwconfig support and query
   - sysfs support for multi-tile
   - fdinfo per-client gpu utilisation
   - add geometry subslices query
   - fix prime mmap with LMEM
   - fix vm open count and remove vma refcounts
   - contiguous allocation fixes
   - steered register write support
   - small PCI BAR enablement
   - GuC error capture support
   - sunset igpu legacy mmap support for newer devices
   - GuC version 70.1.1 support

  amdgpu:
   - Initial SoC21 support
   - SMU 13.x enablement
   - SMU 13.0.4 support
   - ttm_eu cleanups
   - USB-C, GPUVM updates
   - TMZ fixes for RV
   - RAS support for VCN
   - PM sysfs code cleanup
   - DC FP rework
   - extend CG/PG flags to 64-bit
   - SI dpm lockdep fix
   - runtime PM fixes

  amdkfd:
   - RAS/SVM fixes
   - TLB flush fixes
   - CRIU GWS support
   - ignore bogus MEC signals more efficiently

  msm:
   - Fourcc modifier for tiled but not compressed layouts
   - Support for userspace allocated IOVA (GPU virtual address)
   - DPU: DSC (Display Stream Compression) support
   - DP: eDP support
   - DP: conversion to use drm_bridge and drm_bridge_connector
   - Merge DPU1 and MDP5 MDSS driver
   - DPU: writeback support

  nouveau:
   - make some structures static
   - make some variables static
   - switch to drm_gem_plane_helper_prepare_fb

  radeon:
   - misc fixes/cleanups

  mxsfb:
   - rework crtc mode setting
   - LCDIF CRC support

  etnaviv:
   - fencing improvements
   - fix address space collisions
   - cleanup MMU reference handling

  gma500:
   - GEM/GTT improvements
   - connector handling fixes

  komeda:
   - switch to plane reset helper

  mediatek:
   - MIPI DSI improvements

  omapdrm:
   - GEM improvements

  qxl:
   - aarch64 support

  vc4:
   - add a CL submission tracepoint
   - HDMI YUV support
   - HDMI/clock improvements
   - drop is_hdmi caching

  virtio:
   - remove restriction of non-zero blob types

  vmwgfx:
   - support for cursormob and cursorbypass 4
   - fence improvements

  tidss:
   - reset DISPC on startup

  solomon:
   - SPI support
   - DT improvements

  sun4i:
   - allwinner D1 support
   - drop is_hdmi caching

  imx:
   - use swap() instead of open-coding
   - use devm_platform_ioremap_resource
   - remove redunant initializations

  ast:
   - Displayport support

  rockchip:
   - Refactor IOMMU initialisation
   - make some structures static
   - replace drm_detect_hdmi_monitor with drm_display_info.is_hdmi
   - support swapped YUV formats,
   - clock improvements
   - rk3568 support
   - VOP2 support

  mediatek:
   - MT8186 support

  tegra:
   - debugabillity improvements"

* tag 'drm-next-2022-05-25' of git://anongit.freedesktop.org/drm/drm: (1740 commits)
  drm/i915/dsi: fix VBT send packet port selection for ICL+
  drm/i915/uc: Fix undefined behavior due to shift overflowing the constant
  drm/i915/reg: fix undefined behavior due to shift overflowing the constant
  drm/i915/gt: Fix use of static in macro mismatch
  drm/i915/audio: fix audio code enable/disable pipe logging
  drm/i915: Fix CFI violation with show_dynamic_id()
  drm/i915: Fix 'mixing different enum types' warnings in intel_display_power.c
  drm/i915/gt: Fix build error without CONFIG_PM
  drm/msm/dpu: handle pm_runtime_get_sync() errors in bind path
  drm/msm/dpu: add DRM_MODE_ROTATE_180 back to supported rotations
  drm/msm: don't free the IRQ if it was not requested
  drm/msm/dpu: limit writeback modes according to max_linewidth
  drm/amd: Don't reset dGPUs if the system is going to s2idle
  drm/amdgpu: Unmap legacy queue when MES is enabled
  drm: msm: fix possible memory leak in mdp5_crtc_cursor_set()
  drm/msm: Fix fb plane offset calculation
  drm/msm/a6xx: Fix refcount leak in a6xx_gpu_init
  drm/msm/dsi: don't powerup at modeset time for parade-ps8640
  drm/rockchip: Change register space names in vop2
  dt-bindings: display: rockchip: make reg-names mandatory for VOP2
  ...

4 files changed, 334 insertions, 329 deletions

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 53297a0d9c57..32f55640890c 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -216,7 +216,8 @@ static bool dma_buf_poll_add_cb(struct dma_resv *resv, bool write,
 	struct dma_fence *fence;
 	int r;
 
-	dma_resv_for_each_fence(&cursor, resv, write, fence) {
+	dma_resv_for_each_fence(&cursor, resv, dma_resv_usage_rw(write),
+				fence) {
 		dma_fence_get(fence);
 		r = dma_fence_add_callback(fence, &dcb->cb, dma_buf_poll_cb);
 		if (!r)
@@ -451,7 +452,7 @@ err_alloc_file:
  *    as a file descriptor by calling dma_buf_fd().
  *
  * 2. Userspace passes this file-descriptors to all drivers it wants this buffer
- *    to share with: First the filedescriptor is converted to a &dma_buf using
+ *    to share with: First the file descriptor is converted to a &dma_buf using
  *    dma_buf_get(). Then the buffer is attached to the device using
  *    dma_buf_attach().
  *
@@ -668,12 +669,24 @@ static struct sg_table * __map_dma_buf(struct dma_buf_attachment *attach,
 				       enum dma_data_direction direction)
 {
 	struct sg_table *sg_table;
+	signed long ret;
 
 	sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
+	if (IS_ERR_OR_NULL(sg_table))
+		return sg_table;
+
+	if (!dma_buf_attachment_is_dynamic(attach)) {
+		ret = dma_resv_wait_timeout(attach->dmabuf->resv,
+					    DMA_RESV_USAGE_KERNEL, true,
+					    MAX_SCHEDULE_TIMEOUT);
+		if (ret < 0) {
+			attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
+							   direction);
+			return ERR_PTR(ret);
+		}
+	}
 
-	if (!IS_ERR_OR_NULL(sg_table))
-		mangle_sg_table(sg_table);
-
+	mangle_sg_table(sg_table);
 	return sg_table;
 }
 
@@ -1132,7 +1145,8 @@ static int __dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
 	long ret;
 
 	/* Wait on any implicit rendering fences */
-	ret = dma_resv_wait_timeout(resv, write, true, MAX_SCHEDULE_TIMEOUT);
+	ret = dma_resv_wait_timeout(resv, dma_resv_usage_rw(write),
+				    true, MAX_SCHEDULE_TIMEOUT);
 	if (ret < 0)
 		return ret;
 
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index b51416405e86..0cce6e4ec946 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -34,6 +34,7 @@
  */
 
 #include <linux/dma-resv.h>
+#include <linux/dma-fence-array.h>
 #include <linux/export.h>
 #include <linux/mm.h>
 #include <linux/sched/mm.h>
@@ -43,12 +44,12 @@
 /**
  * DOC: Reservation Object Overview
  *
- * The reservation object provides a mechanism to manage shared and
- * exclusive fences associated with a buffer.  A reservation object
- * can have attached one exclusive fence (normally associated with
- * write operations) or N shared fences (read operations).  The RCU
- * mechanism is used to protect read access to fences from locked
- * write-side updates.
+ * The reservation object provides a mechanism to manage a container of
+ * dma_fence object associated with a resource. A reservation object
+ * can have any number of fences attaches to it. Each fence carries an usage
+ * parameter determining how the operation represented by the fence is using the
+ * resource. The RCU mechanism is used to protect read access to fences from
+ * locked write-side updates.
  *
  * See struct dma_resv for more details.
  */
@@ -56,33 +57,59 @@
 DEFINE_WD_CLASS(reservation_ww_class);
 EXPORT_SYMBOL(reservation_ww_class);
 
-/**
- * dma_resv_list_alloc - allocate fence list
- * @shared_max: number of fences we need space for
- *
+/* Mask for the lower fence pointer bits */
+#define DMA_RESV_LIST_MASK	0x3
+
+struct dma_resv_list {
+	struct rcu_head rcu;
+	u32 num_fences, max_fences;
+	struct dma_fence __rcu *table[];
+};
+
+/* Extract the fence and usage flags from an RCU protected entry in the list. */
+static void dma_resv_list_entry(struct dma_resv_list *list, unsigned int index,
+				struct dma_resv *resv, struct dma_fence **fence,
+				enum dma_resv_usage *usage)
+{
+	long tmp;
+
+	tmp = (long)rcu_dereference_check(list->table[index],
+					  resv ? dma_resv_held(resv) : true);
+	*fence = (struct dma_fence *)(tmp & ~DMA_RESV_LIST_MASK);
+	if (usage)
+		*usage = tmp & DMA_RESV_LIST_MASK;
+}
+
+/* Set the fence and usage flags at the specific index in the list. */
+static void dma_resv_list_set(struct dma_resv_list *list,
+			      unsigned int index,
+			      struct dma_fence *fence,
+			      enum dma_resv_usage usage)
+{
+	long tmp = ((long)fence) | usage;
+
+	RCU_INIT_POINTER(list->table[index], (struct dma_fence *)tmp);
+}
+
+/*
  * Allocate a new dma_resv_list and make sure to correctly initialize
- * shared_max.
+ * max_fences.
  */
-static struct dma_resv_list *dma_resv_list_alloc(unsigned int shared_max)
+static struct dma_resv_list *dma_resv_list_alloc(unsigned int max_fences)
 {
 	struct dma_resv_list *list;
 
-	list = kmalloc(struct_size(list, shared, shared_max), GFP_KERNEL);
+	list = kmalloc(struct_size(list, table, max_fences), GFP_KERNEL);
 	if (!list)
 		return NULL;
 
-	list->shared_max = (ksize(list) - offsetof(typeof(*list), shared)) /
-		sizeof(*list->shared);
+	list->max_fences = (ksize(list) - offsetof(typeof(*list), table)) /
+		sizeof(*list->table);
 
 	return list;
 }
 
-/**
- * dma_resv_list_free - free fence list
- * @list: list to free
- *
- * Free a dma_resv_list and make sure to drop all references.
- */
+/* Free a dma_resv_list and make sure to drop all references. */
 static void dma_resv_list_free(struct dma_resv_list *list)
 {
 	unsigned int i;
@@ -90,9 +117,12 @@ static void dma_resv_list_free(struct dma_resv_list *list)
 	if (!list)
 		return;
 
-	for (i = 0; i < list->shared_count; ++i)
-		dma_fence_put(rcu_dereference_protected(list->shared[i], true));
+	for (i = 0; i < list->num_fences; ++i) {
+		struct dma_fence *fence;
 
+		dma_resv_list_entry(list, i, NULL, &fence, NULL);
+		dma_fence_put(fence);
+	}
 	kfree_rcu(list, rcu);
 }
 
@@ -103,10 +133,8 @@ static void dma_resv_list_free(struct dma_resv_list *list)
 void dma_resv_init(struct dma_resv *obj)
 {
 	ww_mutex_init(&obj->lock, &reservation_ww_class);
-	seqcount_ww_mutex_init(&obj->seq, &obj->lock);
 
-	RCU_INIT_POINTER(obj->fence, NULL);
-	RCU_INIT_POINTER(obj->fence_excl, NULL);
+	RCU_INIT_POINTER(obj->fences, NULL);
 }
 EXPORT_SYMBOL(dma_resv_init);
 
@@ -116,51 +144,48 @@ EXPORT_SYMBOL(dma_resv_init);
  */
 void dma_resv_fini(struct dma_resv *obj)
 {
-	struct dma_resv_list *fobj;
-	struct dma_fence *excl;
-
 	/*
 	 * This object should be dead and all references must have
 	 * been released to it, so no need to be protected with rcu.
 	 */
-	excl = rcu_dereference_protected(obj->fence_excl, 1);
-	if (excl)
-		dma_fence_put(excl);
-
-	fobj = rcu_dereference_protected(obj->fence, 1);
-	dma_resv_list_free(fobj);
+	dma_resv_list_free(rcu_dereference_protected(obj->fences, true));
 	ww_mutex_destroy(&obj->lock);
 }
 EXPORT_SYMBOL(dma_resv_fini);
 
+/* Dereference the fences while ensuring RCU rules */
+static inline struct dma_resv_list *dma_resv_fences_list(struct dma_resv *obj)
+{
+	return rcu_dereference_check(obj->fences, dma_resv_held(obj));
+}
+
 /**
- * dma_resv_reserve_shared - Reserve space to add shared fences to
- * a dma_resv.
+ * dma_resv_reserve_fences - Reserve space to add fences to a dma_resv object.
  * @obj: reservation object
  * @num_fences: number of fences we want to add
  *
- * Should be called before dma_resv_add_shared_fence().  Must
- * be called with @obj locked through dma_resv_lock().
+ * Should be called before dma_resv_add_fence().  Must be called with @obj
+ * locked through dma_resv_lock().
  *
  * Note that the preallocated slots need to be re-reserved if @obj is unlocked
- * at any time before calling dma_resv_add_shared_fence(). This is validated
- * when CONFIG_DEBUG_MUTEXES is enabled.
+ * at any time before calling dma_resv_add_fence(). This is validated when
+ * CONFIG_DEBUG_MUTEXES is enabled.
  *
  * RETURNS
  * Zero for success, or -errno
  */
-int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences)
+int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences)
 {
 	struct dma_resv_list *old, *new;
 	unsigned int i, j, k, max;
 
 	dma_resv_assert_held(obj);
 
-	old = dma_resv_shared_list(obj);
-	if (old && old->shared_max) {
-		if ((old->shared_count + num_fences) <= old->shared_max)
+	old = dma_resv_fences_list(obj);
+	if (old && old->max_fences) {
+		if ((old->num_fences + num_fences) <= old->max_fences)
 			return 0;
-		max = max(old->shared_count + num_fences, old->shared_max * 2);
+		max = max(old->num_fences + num_fences, old->max_fences * 2);
 	} else {
 		max = max(4ul, roundup_pow_of_two(num_fences));
 	}
@@ -175,27 +200,27 @@ int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences)
 	 * references from the old struct are carried over to
 	 * the new.
 	 */
-	for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) {
+	for (i = 0, j = 0, k = max; i < (old ? old->num_fences : 0); ++i) {
+		enum dma_resv_usage usage;
 		struct dma_fence *fence;
 
-		fence = rcu_dereference_protected(old->shared[i],
-						  dma_resv_held(obj));
+		dma_resv_list_entry(old, i, obj, &fence, &usage);
 		if (dma_fence_is_signaled(fence))
-			RCU_INIT_POINTER(new->shared[--k], fence);
+			RCU_INIT_POINTER(new->table[--k], fence);
 		else
-			RCU_INIT_POINTER(new->shared[j++], fence);
+			dma_resv_list_set(new, j++, fence, usage);
 	}
-	new->shared_count = j;
+	new->num_fences = j;
 
 	/*
 	 * We are not changing the effective set of fences here so can
 	 * merely update the pointer to the new array; both existing
 	 * readers and new readers will see exactly the same set of
-	 * active (unsignaled) shared fences. Individual fences and the
+	 * active (unsignaled) fences. Individual fences and the
 	 * old array are protected by RCU and so will not vanish under
 	 * the gaze of the rcu_read_lock() readers.
 	 */
-	rcu_assign_pointer(obj->fence, new);
+	rcu_assign_pointer(obj->fences, new);
 
 	if (!old)
 		return 0;
@@ -204,7 +229,7 @@ int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences)
 	for (i = k; i < max; ++i) {
 		struct dma_fence *fence;
 
-		fence = rcu_dereference_protected(new->shared[i],
+		fence = rcu_dereference_protected(new->table[i],
 						  dma_resv_held(obj));
 		dma_fence_put(fence);
 	}
@@ -212,41 +237,43 @@ int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences)
 
 	return 0;
 }
-EXPORT_SYMBOL(dma_resv_reserve_shared);
+EXPORT_SYMBOL(dma_resv_reserve_fences);
 
 #ifdef CONFIG_DEBUG_MUTEXES
 /**
- * dma_resv_reset_shared_max - reset shared fences for debugging
+ * dma_resv_reset_max_fences - reset fences for debugging
  * @obj: the dma_resv object to reset
  *
- * Reset the number of pre-reserved shared slots to test that drivers do
- * correct slot allocation using dma_resv_reserve_shared(). See also
- * &dma_resv_list.shared_max.
+ * Reset the number of pre-reserved fence slots to test that drivers do
+ * correct slot allocation using dma_resv_reserve_fences(). See also
+ * &dma_resv_list.max_fences.
  */
-void dma_resv_reset_shared_max(struct dma_resv *obj)
+void dma_resv_reset_max_fences(struct dma_resv *obj)
 {
-	struct dma_resv_list *fences = dma_resv_shared_list(obj);
+	struct dma_resv_list *fences = dma_resv_fences_list(obj);
 
 	dma_resv_assert_held(obj);
 
-	/* Test shared fence slot reservation */
+	/* Test fence slot reservation */
 	if (fences)
-		fences->shared_max = fences->shared_count;
+		fences->max_fences = fences->num_fences;
 }
-EXPORT_SYMBOL(dma_resv_reset_shared_max);
+EXPORT_SYMBOL(dma_resv_reset_max_fences);
 #endif
 
 /**
- * dma_resv_add_shared_fence - Add a fence to a shared slot
+ * dma_resv_add_fence - Add a fence to the dma_resv obj
  * @obj: the reservation object
- * @fence: the shared fence to add
+ * @fence: the fence to add
+ * @usage: how the fence is used, see enum dma_resv_usage
  *
- * Add a fence to a shared slot, @obj must be locked with dma_resv_lock(), and
- * dma_resv_reserve_shared() has been called.
+ * Add a fence to a slot, @obj must be locked with dma_resv_lock(), and
+ * dma_resv_reserve_fences() has been called.
  *
  * See also &dma_resv.fence for a discussion of the semantics.
  */
-void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence)
+void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence,
+			enum dma_resv_usage usage)
 {
 	struct dma_resv_list *fobj;
 	struct dma_fence *old;
@@ -261,118 +288,105 @@ void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence)
 	 */
 	WARN_ON(dma_fence_is_container(fence));
 
-	fobj = dma_resv_shared_list(obj);
-	count = fobj->shared_count;
-
-	write_seqcount_begin(&obj->seq);
+	fobj = dma_resv_fences_list(obj);
+	count = fobj->num_fences;
 
 	for (i = 0; i < count; ++i) {
-
-		old = rcu_dereference_protected(fobj->shared[i],
-						dma_resv_held(obj));
-		if (old->context == fence->context ||
-		    dma_fence_is_signaled(old))
-			goto replace;
+		enum dma_resv_usage old_usage;
+
+		dma_resv_list_entry(fobj, i, obj, &old, &old_usage);
+		if ((old->context == fence->context && old_usage >= usage) ||
+		    dma_fence_is_signaled(old)) {
+			dma_resv_list_set(fobj, i, fence, usage);
+			dma_fence_put(old);
+			return;
+		}
 	}
 
-	BUG_ON(fobj->shared_count >= fobj->shared_max);
-	old = NULL;
+	BUG_ON(fobj->num_fences >= fobj->max_fences);
 	count++;
 
-replace:
-	RCU_INIT_POINTER(fobj->shared[i], fence);
-	/* pointer update must be visible before we extend the shared_count */
-	smp_store_mb(fobj->shared_count, count);
-
-	write_seqcount_end(&obj->seq);
-	dma_fence_put(old);
+	dma_resv_list_set(fobj, i, fence, usage);
+	/* pointer update must be visible before we extend the num_fences */
+	smp_store_mb(fobj->num_fences, count);
 }
-EXPORT_SYMBOL(dma_resv_add_shared_fence);
+EXPORT_SYMBOL(dma_resv_add_fence);
 
 /**
- * dma_resv_add_excl_fence - Add an exclusive fence.
+ * dma_resv_replace_fences - replace fences in the dma_resv obj
  * @obj: the reservation object
- * @fence: the exclusive fence to add
+ * @context: the context of the fences to replace
+ * @replacement: the new fence to use instead
+ * @usage: how the new fence is used, see enum dma_resv_usage
+ *
+ * Replace fences with a specified context with a new fence. Only valid if the
+ * operation represented by the original fence has no longer access to the
+ * resources represented by the dma_resv object when the new fence completes.
  *
- * Add a fence to the exclusive slot. @obj must be locked with dma_resv_lock().
- * Note that this function replaces all fences attached to @obj, see also
- * &dma_resv.fence_excl for a discussion of the semantics.
+ * And example for using this is replacing a preemption fence with a page table
+ * update fence which makes the resource inaccessible.
  */
-void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
+void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
+			     struct dma_fence *replacement,
+			     enum dma_resv_usage usage)
 {
-	struct dma_fence *old_fence = dma_resv_excl_fence(obj);
-	struct dma_resv_list *old;
-	u32 i = 0;
+	struct dma_resv_list *list;
+	unsigned int i;
 
 	dma_resv_assert_held(obj);
 
-	old = dma_resv_shared_list(obj);
-	if (old)
-		i = old->shared_count;
-
-	dma_fence_get(fence);
-
-	write_seqcount_begin(&obj->seq);
-	/* write_seqcount_begin provides the necessary memory barrier */
-	RCU_INIT_POINTER(obj->fence_excl, fence);
-	if (old)
-		old->shared_count = 0;
-	write_seqcount_end(&obj->seq);
+	list = dma_resv_fences_list(obj);
+	for (i = 0; list && i < list->num_fences; ++i) {
+		struct dma_fence *old;
 
-	/* inplace update, no shared fences */
-	while (i--)
-		dma_fence_put(rcu_dereference_protected(old->shared[i],
-						dma_resv_held(obj)));
+		dma_resv_list_entry(list, i, obj, &old, NULL);
+		if (old->context != context)
+			continue;
 
-	dma_fence_put(old_fence);
+		dma_resv_list_set(list, i, replacement, usage);
+		dma_fence_put(old);
+	}
 }
-EXPORT_SYMBOL(dma_resv_add_excl_fence);
+EXPORT_SYMBOL(dma_resv_replace_fences);
 
-/* Restart the iterator by initializing all the necessary fields, but not the
- * relation to the dma_resv object. */
+/* Restart the unlocked iteration by initializing the cursor object. */
 static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor)
 {
-	cursor->seq = read_seqcount_begin(&cursor->obj->seq);
-	cursor->index = -1;
-	cursor->shared_count = 0;
-	if (cursor->all_fences) {
-		cursor->fences = dma_resv_shared_list(cursor->obj);
-		if (cursor->fences)
-			cursor->shared_count = cursor->fences->shared_count;
-	} else {
-		cursor->fences = NULL;
-	}
+	cursor->index = 0;
+	cursor->num_fences = 0;
+	cursor->fences = dma_resv_fences_list(cursor->obj);
+	if (cursor->fences)
+		cursor->num_fences = cursor->fences->num_fences;
 	cursor->is_restarted = true;
 }
 
 /* Walk to the next not signaled fence and grab a reference to it */
 static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor)
 {
-	struct dma_resv *obj = cursor->obj;
+	if (!cursor->fences)
+		return;
 
 	do {
 		/* Drop the reference from the previous round */
 		dma_fence_put(cursor->fence);
 
-		if (cursor->index == -1) {
-			cursor->fence = dma_resv_excl_fence(obj);
-			cursor->index++;
-			if (!cursor->fence)
-				continue;
-
-		} else if (!cursor->fences ||
-			   cursor->index >= cursor->shared_count) {
+		if (cursor->index >= cursor->num_fences) {
 			cursor->fence = NULL;
 			break;
 
-		} else {
-			struct dma_resv_list *fences = cursor->fences;
-			unsigned int idx = cursor->index++;
-
-			cursor->fence = rcu_dereference(fences->shared[idx]);
 		}
+
+		dma_resv_list_entry(cursor->fences, cursor->index++,
+				    cursor->obj, &cursor->fence,
+				    &cursor->fence_usage);
 		cursor->fence = dma_fence_get_rcu(cursor->fence);
-		if (!cursor->fence || !dma_fence_is_signaled(cursor->fence))
+		if (!cursor->fence) {
+			dma_resv_iter_restart_unlocked(cursor);
+			continue;
+		}
+
+		if (!dma_fence_is_signaled(cursor->fence) &&
+		    cursor->usage >= cursor->fence_usage)
 			break;
 	} while (true);
 }
@@ -395,7 +409,7 @@ struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor)
 	do {
 		dma_resv_iter_restart_unlocked(cursor);
 		dma_resv_iter_walk_unlocked(cursor);
-	} while (read_seqcount_retry(&cursor->obj->seq, cursor->seq));
+	} while (dma_resv_fences_list(cursor->obj) != cursor->fences);
 	rcu_read_unlock();
 
 	return cursor->fence;
@@ -418,13 +432,13 @@ struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
 
 	rcu_read_lock();
 	cursor->is_restarted = false;
-	restart = read_seqcount_retry(&cursor->obj->seq, cursor->seq);
+	restart = dma_resv_fences_list(cursor->obj) != cursor->fences;
 	do {
 		if (restart)
 			dma_resv_iter_restart_unlocked(cursor);
 		dma_resv_iter_walk_unlocked(cursor);
 		restart = true;
-	} while (read_seqcount_retry(&cursor->obj->seq, cursor->seq));
+	} while (dma_resv_fences_list(cursor->obj) != cursor->fences);
 	rcu_read_unlock();
 
 	return cursor->fence;
@@ -447,15 +461,9 @@ struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
 	dma_resv_assert_held(cursor->obj);
 
 	cursor->index = 0;
-	if (cursor->all_fences)
-		cursor->fences = dma_resv_shared_list(cursor->obj);
-	else
-		cursor->fences = NULL;
-
-	fence = dma_resv_excl_fence(cursor->obj);
-	if (!fence)
-		fence = dma_resv_iter_next(cursor);
+	cursor->fences = dma_resv_fences_list(cursor->obj);
 
+	fence = dma_resv_iter_next(cursor);
 	cursor->is_restarted = true;
 	return fence;
 }
@@ -470,17 +478,22 @@ EXPORT_SYMBOL_GPL(dma_resv_iter_first);
  */
 struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
 {
-	unsigned int idx;
+	struct dma_fence *fence;
 
 	dma_resv_assert_held(cursor->obj);
 
 	cursor->is_restarted = false;
-	if (!cursor->fences || cursor->index >= cursor->fences->shared_count)
-		return NULL;
 
-	idx = cursor->index++;
-	return rcu_dereference_protected(cursor->fences->shared[idx],
-					 dma_resv_held(cursor->obj));
+	do {
+		if (!cursor->fences ||
+		    cursor->index >= cursor->fences->num_fences)
+			return NULL;
+
+		dma_resv_list_entry(cursor->fences, cursor->index++,
+				    cursor->obj, &fence, &cursor->fence_usage);
+	} while (cursor->fence_usage > cursor->usage);
+
+	return fence;
 }
 EXPORT_SYMBOL_GPL(dma_resv_iter_next);
 
@@ -495,60 +508,43 @@ int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
 {
 	struct dma_resv_iter cursor;
 	struct dma_resv_list *list;
-	struct dma_fence *f, *excl;
+	struct dma_fence *f;
 
 	dma_resv_assert_held(dst);
 
 	list = NULL;
-	excl = NULL;
 
-	dma_resv_iter_begin(&cursor, src, true);
+	dma_resv_iter_begin(&cursor, src, DMA_RESV_USAGE_BOOKKEEP);
 	dma_resv_for_each_fence_unlocked(&cursor, f) {
 
 		if (dma_resv_iter_is_restarted(&cursor)) {
 			dma_resv_list_free(list);
-			dma_fence_put(excl);
-
-			if (cursor.shared_count) {
-				list = dma_resv_list_alloc(cursor.shared_count);
-				if (!list) {
-					dma_resv_iter_end(&cursor);
-					return -ENOMEM;
-				}
 
-				list->shared_count = 0;
-
-			} else {
-				list = NULL;
+			list = dma_resv_list_alloc(cursor.num_fences);
+			if (!list) {
+				dma_resv_iter_end(&cursor);
+				return -ENOMEM;
 			}
-			excl = NULL;
+			list->num_fences = 0;
 		}
 
 		dma_fence_get(f);
-		if (dma_resv_iter_is_exclusive(&cursor))
-			excl = f;
-		else
-			RCU_INIT_POINTER(list->shared[list->shared_count++], f);
+		dma_resv_list_set(list, list->num_fences++, f,
+				  dma_resv_iter_usage(&cursor));
 	}
 	dma_resv_iter_end(&cursor);
 
-	write_seqcount_begin(&dst->seq);
-	excl = rcu_replace_pointer(dst->fence_excl, excl, dma_resv_held(dst));
-	list = rcu_replace_pointer(dst->fence, list, dma_resv_held(dst));
-	write_seqcount_end(&dst->seq);
-
+	list = rcu_replace_pointer(dst->fences, list, dma_resv_held(dst));
 	dma_resv_list_free(list);
-	dma_fence_put(excl);
-
 	return 0;
 }
 EXPORT_SYMBOL(dma_resv_copy_fences);
 
 /**
- * dma_resv_get_fences - Get an object's shared and exclusive
+ * dma_resv_get_fences - Get an object's fences
  * fences without update side lock held
  * @obj: the reservation object
- * @write: true if we should return all fences
+ * @usage: controls which fences to include, see enum dma_resv_usage.
  * @num_fences: the number of fences returned
  * @fences: the array of fence ptrs returned (array is krealloc'd to the
  * required size, and must be freed by caller)
@@ -556,7 +552,7 @@ EXPORT_SYMBOL(dma_resv_copy_fences);
  * Retrieve all fences from the reservation object.
  * Returns either zero or -ENOMEM.
  */
-int dma_resv_get_fences(struct dma_resv *obj, bool write,
+int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
 			unsigned int *num_fences, struct dma_fence ***fences)
 {
 	struct dma_resv_iter cursor;
@@ -565,7 +561,7 @@ int dma_resv_get_fences(struct dma_resv *obj, bool write,
 	*num_fences = 0;
 	*fences = NULL;
 
-	dma_resv_iter_begin(&cursor, obj, write);
+	dma_resv_iter_begin(&cursor, obj, usage);
 	dma_resv_for_each_fence_unlocked(&cursor, fence) {
 
 		if (dma_resv_iter_is_restarted(&cursor)) {
@@ -574,7 +570,7 @@ int dma_resv_get_fences(struct dma_resv *obj, bool write,
 			while (*num_fences)
 				dma_fence_put((*fences)[--(*num_fences)]);
 
-			count = cursor.shared_count + 1;
+			count = cursor.num_fences + 1;
 
 			/* Eventually re-allocate the array */
 			*fences = krealloc_array(*fences, count,
@@ -595,10 +591,62 @@ int dma_resv_get_fences(struct dma_resv *obj, bool write,
 EXPORT_SYMBOL_GPL(dma_resv_get_fences);
 
 /**
- * dma_resv_wait_timeout - Wait on reservation's objects
- * shared and/or exclusive fences.
+ * dma_resv_get_singleton - Get a single fence for all the fences
+ * @obj: the reservation object
+ * @usage: controls which fences to include, see enum dma_resv_usage.
+ * @fence: the resulting fence
+ *
+ * Get a single fence representing all the fences inside the resv object.
+ * Returns either 0 for success or -ENOMEM.
+ *
+ * Warning: This can't be used like this when adding the fence back to the resv
+ * object since that can lead to stack corruption when finalizing the
+ * dma_fence_array.
+ *
+ * Returns 0 on success and negative error values on failure.
+ */
+int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage,
+			   struct dma_fence **fence)
+{
+	struct dma_fence_array *array;
+	struct dma_fence **fences;
+	unsigned count;
+	int r;
+
+	r = dma_resv_get_fences(obj, usage, &count, &fences);
+        if (r)
+		return r;
+
+	if (count == 0) {
+		*fence = NULL;
+		return 0;
+	}
+
+	if (count == 1) {
+		*fence = fences[0];
+		kfree(fences);
+		return 0;
+	}
+
+	array = dma_fence_array_create(count, fences,
+				       dma_fence_context_alloc(1),
+				       1, false);
+	if (!array) {
+		while (count--)
+			dma_fence_put(fences[count]);
+		kfree(fences);
+		return -ENOMEM;
+	}
+
+	*fence = &array->base;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dma_resv_get_singleton);
+
+/**
+ * dma_resv_wait_timeout - Wait on reservation's objects fences
  * @obj: the reservation object
- * @wait_all: if true, wait on all fences, else wait on just exclusive fence
+ * @usage: controls which fences to include, see enum dma_resv_usage.
  * @intr: if true, do interruptible wait
  * @timeout: timeout value in jiffies or zero to return immediately
  *
@@ -608,14 +656,14 @@ EXPORT_SYMBOL_GPL(dma_resv_get_fences);
  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
  * greater than zer on success.
  */
-long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr,
-			   unsigned long timeout)
+long dma_resv_wait_timeout(struct dma_resv *obj, enum dma_resv_usage usage,
+			   bool intr, unsigned long timeout)
 {
 	long ret = timeout ? timeout : 1;
 	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
 
-	dma_resv_iter_begin(&cursor, obj, wait_all);
+	dma_resv_iter_begin(&cursor, obj, usage);
 	dma_resv_for_each_fence_unlocked(&cursor, fence) {
 
 		ret = dma_fence_wait_timeout(fence, intr, ret);
@@ -635,8 +683,7 @@ EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
  * dma_resv_test_signaled - Test if a reservation object's fences have been
  * signaled.
  * @obj: the reservation object
- * @test_all: if true, test all fences, otherwise only test the exclusive
- * fence
+ * @usage: controls which fences to include, see enum dma_resv_usage.
  *
  * Callers are not required to hold specific locks, but maybe hold
  * dma_resv_lock() already.
@@ -645,12 +692,12 @@ EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
  *
  * True if all fences signaled, else false.
  */
-bool dma_resv_test_signaled(struct dma_resv *obj, bool test_all)
+bool dma_resv_test_signaled(struct dma_resv *obj, enum dma_resv_usage usage)
 {
 	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
 
-	dma_resv_iter_begin(&cursor, obj, test_all);
+	dma_resv_iter_begin(&cursor, obj, usage);
 	dma_resv_for_each_fence_unlocked(&cursor, fence) {
 		dma_resv_iter_end(&cursor);
 		return false;
@@ -670,13 +717,13 @@ EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
  */
 void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq)
 {
+	static const char *usage[] = { "kernel", "write", "read", "bookkeep" };
 	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
 
-	dma_resv_for_each_fence(&cursor, obj, true, fence) {
+	dma_resv_for_each_fence(&cursor, obj, DMA_RESV_USAGE_READ, fence) {
 		seq_printf(seq, "\t%s fence:",
-			   dma_resv_iter_is_exclusive(&cursor) ?
-				"Exclusive" : "Shared");
+			   usage[dma_resv_iter_usage(&cursor)]);
 		dma_fence_describe(fence, seq);
 	}
 }
diff --git a/drivers/dma-buf/st-dma-resv.c b/drivers/dma-buf/st-dma-resv.c
index cbe999c6e7a6..813779e3c9be 100644
--- a/drivers/dma-buf/st-dma-resv.c
+++ b/drivers/dma-buf/st-dma-resv.c
@@ -58,8 +58,9 @@ static int sanitycheck(void *arg)
 	return r;
 }
 
-static int test_signaling(void *arg, bool shared)
+static int test_signaling(void *arg)
 {
+	enum dma_resv_usage usage = (unsigned long)arg;
 	struct dma_resv resv;
 	struct dma_fence *f;
 	int r;
@@ -75,25 +76,20 @@ static int test_signaling(void *arg, bool shared)
 		goto err_free;
 	}
 
-	if (shared) {
-		r = dma_resv_reserve_shared(&resv, 1);
-		if (r) {
-			pr_err("Resv shared slot allocation failed\n");
-			goto err_unlock;
-		}
-
-		dma_resv_add_shared_fence(&resv, f);
-	} else {
-		dma_resv_add_excl_fence(&resv, f);
+	r = dma_resv_reserve_fences(&resv, 1);
+	if (r) {
+		pr_err("Resv shared slot allocation failed\n");
+		goto err_unlock;
 	}
 
-	if (dma_resv_test_signaled(&resv, shared)) {
+	dma_resv_add_fence(&resv, f, usage);
+	if (dma_resv_test_signaled(&resv, usage)) {
 		pr_err("Resv unexpectedly signaled\n");
 		r = -EINVAL;
 		goto err_unlock;
 	}
 	dma_fence_signal(f);
-	if (!dma_resv_test_signaled(&resv, shared)) {
+	if (!dma_resv_test_signaled(&resv, usage)) {
 		pr_err("Resv not reporting signaled\n");
 		r = -EINVAL;
 		goto err_unlock;
@@ -106,18 +102,9 @@ err_free:
 	return r;
 }
 
-static int test_excl_signaling(void *arg)
-{
-	return test_signaling(arg, false);
-}
-
-static int test_shared_signaling(void *arg)
-{
-	return test_signaling(arg, true);
-}
-
-static int test_for_each(void *arg, bool shared)
+static int test_for_each(void *arg)
 {
+	enum dma_resv_usage usage = (unsigned long)arg;
 	struct dma_resv_iter cursor;
 	struct dma_fence *f, *fence;
 	struct dma_resv resv;
@@ -134,20 +121,16 @@ static int test_for_each(void *arg, bool shared)
 		goto err_free;
 	}
 
-	if (shared) {
-		r = dma_resv_reserve_shared(&resv, 1);
-		if (r) {
-			pr_err("Resv shared slot allocation failed\n");
-			goto err_unlock;
-		}
-
-		dma_resv_add_shared_fence(&resv, f);
-	} else {
-		dma_resv_add_excl_fence(&resv, f);
+	r = dma_resv_reserve_fences(&resv, 1);
+	if (r) {
+		pr_err("Resv shared slot allocation failed\n");
+		goto err_unlock;
 	}
 
+	dma_resv_add_fence(&resv, f, usage);
+
 	r = -ENOENT;
-	dma_resv_for_each_fence(&cursor, &resv, shared, fence) {
+	dma_resv_for_each_fence(&cursor, &resv, usage, fence) {
 		if (!r) {
 			pr_err("More than one fence found\n");
 			r = -EINVAL;
@@ -158,7 +141,7 @@ static int test_for_each(void *arg, bool shared)
 			r = -EINVAL;
 			goto err_unlock;
 		}
-		if (dma_resv_iter_is_exclusive(&cursor) != !shared) {
+		if (dma_resv_iter_usage(&cursor) != usage) {
 			pr_err("Unexpected fence usage\n");
 			r = -EINVAL;
 			goto err_unlock;
@@ -178,18 +161,9 @@ err_free:
 	return r;
 }
 
-static int test_excl_for_each(void *arg)
-{
-	return test_for_each(arg, false);
-}
-
-static int test_shared_for_each(void *arg)
-{
-	return test_for_each(arg, true);
-}
-
-static int test_for_each_unlocked(void *arg, bool shared)
+static int test_for_each_unlocked(void *arg)
 {
+	enum dma_resv_usage usage = (unsigned long)arg;
 	struct dma_resv_iter cursor;
 	struct dma_fence *f, *fence;
 	struct dma_resv resv;
@@ -206,22 +180,18 @@ static int test_for_each_unlocked(void *arg, bool shared)
 		goto err_free;
 	}
 
-	if (shared) {
-		r = dma_resv_reserve_shared(&resv, 1);
-		if (r) {
-			pr_err("Resv shared slot allocation failed\n");
-			dma_resv_unlock(&resv);
-			goto err_free;
-		}
-
-		dma_resv_add_shared_fence(&resv, f);
-	} else {
-		dma_resv_add_excl_fence(&resv, f);
+	r = dma_resv_reserve_fences(&resv, 1);
+	if (r) {
+		pr_err("Resv shared slot allocation failed\n");
+		dma_resv_unlock(&resv);
+		goto err_free;
 	}
+
+	dma_resv_add_fence(&resv, f, usage);
 	dma_resv_unlock(&resv);
 
 	r = -ENOENT;
-	dma_resv_iter_begin(&cursor, &resv, shared);
+	dma_resv_iter_begin(&cursor, &resv, usage);
 	dma_resv_for_each_fence_unlocked(&cursor, fence) {
 		if (!r) {
 			pr_err("More than one fence found\n");
@@ -237,7 +207,7 @@ static int test_for_each_unlocked(void *arg, bool shared)
 			r = -EINVAL;
 			goto err_iter_end;
 		}
-		if (dma_resv_iter_is_exclusive(&cursor) != !shared) {
+		if (dma_resv_iter_usage(&cursor) != usage) {
 			pr_err("Unexpected fence usage\n");
 			r = -EINVAL;
 			goto err_iter_end;
@@ -247,7 +217,7 @@ static int test_for_each_unlocked(void *arg, bool shared)
 		if (r == -ENOENT) {
 			r = -EINVAL;
 			/* That should trigger an restart */
-			cursor.seq--;
+			cursor.fences = (void*)~0;
 		} else if (r == -EINVAL) {
 			r = 0;
 		}
@@ -263,18 +233,9 @@ err_free:
 	return r;
 }
 
-static int test_excl_for_each_unlocked(void *arg)
-{
-	return test_for_each_unlocked(arg, false);
-}
-
-static int test_shared_for_each_unlocked(void *arg)
-{
-	return test_for_each_unlocked(arg, true);
-}
-
-static int test_get_fences(void *arg, bool shared)
+static int test_get_fences(void *arg)
 {
+	enum dma_resv_usage usage = (unsigned long)arg;
 	struct dma_fence *f, **fences = NULL;
 	struct dma_resv resv;
 	int r, i;
@@ -290,21 +251,17 @@ static int test_get_fences(void *arg, bool shared)
 		goto err_resv;
 	}
 
-	if (shared) {
-		r = dma_resv_reserve_shared(&resv, 1);
-		if (r) {
-			pr_err("Resv shared slot allocation failed\n");
-			dma_resv_unlock(&resv);
-			goto err_resv;
-		}
-
-		dma_resv_add_shared_fence(&resv, f);
-	} else {
-		dma_resv_add_excl_fence(&resv, f);
+	r = dma_resv_reserve_fences(&resv, 1);
+	if (r) {
+		pr_err("Resv shared slot allocation failed\n");
+		dma_resv_unlock(&resv);
+		goto err_resv;
 	}
+
+	dma_resv_add_fence(&resv, f, usage);
 	dma_resv_unlock(&resv);
 
-	r = dma_resv_get_fences(&resv, shared, &i, &fences);
+	r = dma_resv_get_fences(&resv, usage, &i, &fences);
 	if (r) {
 		pr_err("get_fences failed\n");
 		goto err_free;
@@ -326,30 +283,24 @@ err_resv:
 	return r;
 }
 
-static int test_excl_get_fences(void *arg)
-{
-	return test_get_fences(arg, false);
-}
-
-static int test_shared_get_fences(void *arg)
-{
-	return test_get_fences(arg, true);
-}
-
 int dma_resv(void)
 {
 	static const struct subtest tests[] = {
 		SUBTEST(sanitycheck),
-		SUBTEST(test_excl_signaling),
-		SUBTEST(test_shared_signaling),
-		SUBTEST(test_excl_for_each),
-		SUBTEST(test_shared_for_each),
-		SUBTEST(test_excl_for_each_unlocked),
-		SUBTEST(test_shared_for_each_unlocked),
-		SUBTEST(test_excl_get_fences),
-		SUBTEST(test_shared_get_fences),
+		SUBTEST(test_signaling),
+		SUBTEST(test_for_each),
+		SUBTEST(test_for_each_unlocked),
+		SUBTEST(test_get_fences),
 	};
+	enum dma_resv_usage usage;
+	int r;
 
 	spin_lock_init(&fence_lock);
-	return subtests(tests, NULL);
+	for (usage = DMA_RESV_USAGE_KERNEL; usage <= DMA_RESV_USAGE_BOOKKEEP;
+	     ++usage) {
+		r = subtests(tests, (void *)(unsigned long)usage);
+		if (r)
+			return r;
+	}
+	return 0;
 }
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
index 514d213261df..0fe564539166 100644
--- a/drivers/dma-buf/sync_file.c
+++ b/drivers/dma-buf/sync_file.c
@@ -157,9 +157,15 @@ static int sync_file_set_fence(struct sync_file *sync_file,
 	 * we already own a new reference to the fence. For num_fence > 1
 	 * we own the reference of the dma_fence_array creation.
 	 */
-	if (num_fences == 1) {
+
+	if (num_fences == 0) {
+		sync_file->fence = dma_fence_get_stub();
+		kfree(fences);
+
+	} else if (num_fences == 1) {
 		sync_file->fence = fences[0];
 		kfree(fences);
+
 	} else {
 		array = dma_fence_array_create(num_fences, fences,
 					       dma_fence_context_alloc(1),
@@ -261,19 +267,6 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
 		}
 	}
 
-	if (index == 0)
-		fences[index++] = dma_fence_get_stub();
-
-	if (num_fences > index) {
-		struct dma_fence **tmp;
-
-		/* Keep going even when reducing the size failed */
-		tmp = krealloc_array(fences, index, sizeof(*fences),
-				     GFP_KERNEL);
-		if (tmp)
-			fences = tmp;
-	}
-
 	if (sync_file_set_fence(sync_file, fences, index) < 0)
 		goto err_put_fences;