Am 10.06.21 um 23:09 schrieb Jason Ekstrand:
Add a helper function to get a single fence representing
all fences in a dma_resv object.
This fence is either the only one in the object or all not
signaled fences of the object in a flatted out dma_fence_array.
v2 (Jason Ekstrand):
- Take reference of fences both for creating the dma_fence_array and in
the case where we return one fence.
- Handle the case where dma_resv_get_list() returns NULL
v3 (Jason Ekstrand):
- Add an _rcu suffix because it is read-only
- Rewrite to use dma_resv_get_fences_rcu so it's RCU-safe
- Add an EXPORT_SYMBOL_GPL declaration
- Re-author the patch to Jason since very little is left of Christian
König's original patch
- Remove the extra fence argument
v4 (Jason Ekstrand):
- Restore the extra fence argument
v5 (Daniel Vetter):
- Rename from _rcu to _unlocked since it doesn't leak RCU details to
the caller
- Fix docs
- Use ERR_PTR for error handling rather than an output dma_fence**
v5 (Jason Ekstrand):
- Drop the extra fence param and leave that to a separate patch
v6 (Jason Ekstrand):
- Rename to dma_resv_get_singleton to match the new naming convention
for dma_resv helpers which work without taking a lock.
Signed-off-by: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Reviewed-by: Christian König <christian.koenig@xxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
---
drivers/dma-buf/dma-resv.c | 91 ++++++++++++++++++++++++++++++++++++++
include/linux/dma-resv.h | 1 +
2 files changed, 92 insertions(+)
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index f26c71747d43a..1b26aa7e5d81c 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -34,6 +34,8 @@
*/
#include <linux/dma-resv.h>
+#include <linux/dma-fence-chain.h>
+#include <linux/dma-fence-array.h>
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/sched/mm.h>
@@ -50,6 +52,10 @@
* write-side updates.
*/
+#define dma_fence_deep_dive_for_each(fence, chain, index, head) \
+ dma_fence_chain_for_each(chain, head) \
+ dma_fence_array_for_each(fence, index, chain)
+
DEFINE_WD_CLASS(reservation_ww_class);
EXPORT_SYMBOL(reservation_ww_class);
@@ -495,6 +501,91 @@ int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
}
EXPORT_SYMBOL_GPL(dma_resv_get_fences);
+/**
+ * dma_resv_get_singleton - get a single fence for the dma_resv object
+ * @obj: the reservation object
+ *
+ * Get a single fence representing all unsignaled fences in the dma_resv object
+ * plus the given extra fence. If we got only one fence return a new
+ * reference to that, otherwise return a dma_fence_array object.
+ *
+ * RETURNS
+ * The singleton dma_fence on success or an ERR_PTR on failure
+ */
+struct dma_fence *dma_resv_get_singleton(struct dma_resv *obj)
+{
+ struct dma_fence *result, **resv_fences, *fence, *chain, **fences;
+ struct dma_fence_array *array;
+ unsigned int num_resv_fences, num_fences;
+ unsigned int err, i, j;
+
+ err = dma_resv_get_fences(obj, NULL, &num_resv_fences, &resv_fences);
+ if (err)
+ return ERR_PTR(err);
+
+ if (num_resv_fences == 0)
+ return NULL;
+
+ num_fences = 0;
+ result = NULL;
+
+ for (i = 0; i < num_resv_fences; ++i) {
+ dma_fence_deep_dive_for_each(fence, chain, j, resv_fences[i]) {
+ if (dma_fence_is_signaled(fence))
+ continue;
+
+ result = fence;
+ ++num_fences;
+ }
+ }
+
+ if (num_fences <= 1) {
+ result = dma_fence_get(result);
+ goto put_resv_fences;
+ }
+
+ fences = kmalloc_array(num_fences, sizeof(struct dma_fence *),
+ GFP_KERNEL);
+ if (!fences) {
+ result = ERR_PTR(-ENOMEM);
+ goto put_resv_fences;
+ }
+
+ num_fences = 0;
+ for (i = 0; i < num_resv_fences; ++i) {
+ dma_fence_deep_dive_for_each(fence, chain, j, resv_fences[i]) {
+ if (!dma_fence_is_signaled(fence))
+ fences[num_fences++] = dma_fence_get(fence);
+ }
+ }
+
+ if (num_fences <= 1) {
+ result = num_fences ? fences[0] : NULL;
+ kfree(fences);
+ goto put_resv_fences;
+ }
+
+ array = dma_fence_array_create(num_fences, fences,
+ dma_fence_context_alloc(1),
+ 1, false);
+ if (array) {
+ result = &array->base;
+ } else {
+ result = ERR_PTR(-ENOMEM);
+ while (num_fences--)
+ dma_fence_put(fences[num_fences]);
+ kfree(fences);
+ }
+
+put_resv_fences:
+ while (num_resv_fences--)
+ dma_fence_put(resv_fences[num_resv_fences]);
+ kfree(resv_fences);
+
+ return result;
+}
+EXPORT_SYMBOL_GPL(dma_resv_get_singleton);
+
/**
* dma_resv_wait_timeout - 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 562b885cf9c3d..d60982975a786 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -275,6 +275,7 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
unsigned *pshared_count, struct dma_fence ***pshared);
int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
+struct dma_fence *dma_resv_get_singleton(struct dma_resv *obj);
long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr,
unsigned long timeout);
bool dma_resv_test_signaled(struct dma_resv *obj, bool test_all);
