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From d24c7e4bc3ac3367910efd78e2aa413df224c231 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>
Date: Wed, 3 Nov 2021 10:02:08 +0100
Subject: [PATCH] dma-buf: add dma_resv_get_singleton v2
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Add a function to simplify getting a single fence for all the fences in
the dma_resv object.
v2: fix ref leak in error handling
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220321135856.1331-3-christian.koenig@amd.com
(cherry picked from commit 92cedee6a6a3e6fcc3ffc0e3866baae5f6f76ac1)
---
drivers/dma-buf/dma-resv.c | 59 ++++++++++++++++++++++++++++++++++++++
include/linux/dma-resv.h | 2 ++
2 files changed, 61 insertions(+)
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 1187e5e80eded..35cca3ca4dcfe 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -33,6 +33,7 @@
*/
#include <linux/dma-resv.h>
+#include <linux/dma-fence-array.h>
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/sched/mm.h>
@@ -517,6 +518,64 @@ int dma_resv_get_fences_rcu(struct dma_resv *obj,
}
EXPORT_SYMBOL_GPL(dma_resv_get_fences_rcu);
+/**
+ * dma_resv_get_singleton - Get a single fence for all the fences
+ * @obj: the reservation object
+ * @write: true if we should return all fences
+ * @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, bool write,
+ struct dma_fence **fence)
+{
+ struct dma_fence_array *array;
+ struct dma_fence **fences;
+ unsigned count;
+ int r;
+
+ if (!write) {
+ *fence = dma_resv_get_excl_rcu(obj);
+ return 0;
+ }
+
+ r = dma_resv_get_fences_rcu(obj, NULL, &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_rcu - Wait on reservation's objects
* shared and/or exclusive fences.
diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index d44a77e8a7e34..171ff5e7ff885 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -283,6 +283,8 @@ int dma_resv_get_fences_rcu(struct dma_resv *obj,
unsigned *pshared_count,
struct dma_fence ***pshared);
+int dma_resv_get_singleton(struct dma_resv *obj, bool write,
+ struct dma_fence **fence);
int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
long dma_resv_wait_timeout_rcu(struct dma_resv *obj, bool wait_all, bool intr,
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