[PATCH 3/3] dma-buf: generalize fence merging
Christian König
ckoenig.leichtzumerken at gmail.com
Tue Apr 26 12:46:37 UTC 2022
Introduce a dma_fence_merge() macro which allows to unwrap fences which
potentially can be containers as well and then merge them back together
into a flat dma_fence_array.
Signed-off-by: Christian König <christian.koenig at amd.com>
---
drivers/dma-buf/dma-fence-unwrap.c | 95 ++++++++++++++++++++
drivers/dma-buf/st-dma-fence-unwrap.c | 47 ++++++++++
drivers/dma-buf/sync_file.c | 119 ++------------------------
include/linux/dma-fence-unwrap.h | 24 ++++++
4 files changed, 172 insertions(+), 113 deletions(-)
diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
index 711be125428c..c9becc74896d 100644
--- a/drivers/dma-buf/dma-fence-unwrap.c
+++ b/drivers/dma-buf/dma-fence-unwrap.c
@@ -11,6 +11,7 @@
#include <linux/dma-fence-array.h>
#include <linux/dma-fence-chain.h>
#include <linux/dma-fence-unwrap.h>
+#include <linux/slab.h>
/* Internal helper to start new array iteration, don't use directly */
static struct dma_fence *
@@ -57,3 +58,97 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor)
return __dma_fence_unwrap_array(cursor);
}
EXPORT_SYMBOL_GPL(dma_fence_unwrap_next);
+
+/* Implementation for the dma_fence_merge() marco, don't use directly */
+struct dma_fence *__dma_fence_merge(unsigned int num_fences,
+ struct dma_fence **fences,
+ struct dma_fence_unwrap *iter)
+{
+ struct dma_fence_array *result;
+ struct dma_fence *tmp, **array;
+ unsigned int i, count;
+
+ count = 0;
+ for (i = 0; i < num_fences; ++i) {
+ dma_fence_unwrap_for_each(tmp, &iter[i], fences[i])
+ if (!dma_fence_is_signaled(tmp))
+ ++count;
+ }
+
+ if (count == 0)
+ return dma_fence_get_stub();
+
+ if (count > INT_MAX)
+ return NULL;
+
+ array = kmalloc_array(count, sizeof(*array), GFP_KERNEL);
+ if (!array)
+ return NULL;
+
+ /*
+ * We can't guarantee that inpute fences are ordered by context, but
+ * it is still quite likely when this function is used multiple times.
+ * So attempt to order the fences by context as we pass over them and
+ * merge fences with the same context.
+ */
+ for (i = 0; i < num_fences; ++i)
+ fences[i] = dma_fence_unwrap_first(fences[i], &iter[i]);
+
+ count = 0;
+ do {
+ unsigned int sel;
+
+restart:
+ tmp = NULL;
+ for (i = 0; i < num_fences; ++i) {
+ struct dma_fence *next = fences[i];
+
+ if (!next || dma_fence_is_signaled(next))
+ continue;
+
+ if (!tmp || tmp->context > next->context) {
+ tmp = next;
+ sel = i;
+
+ } else if (tmp->context < next->context) {
+ continue;
+
+ } else if (dma_fence_is_later(tmp, next)) {
+ fences[i] = dma_fence_unwrap_next(&iter[i]);
+ goto restart;
+ } else {
+ fences[sel] = dma_fence_unwrap_next(&iter[sel]);
+ goto restart;
+ }
+ }
+
+ if (tmp) {
+ array[count++] = dma_fence_get(tmp);
+ fences[sel] = dma_fence_unwrap_next(&iter[sel]);
+ }
+ } while (tmp);
+
+ if (count == 0) {
+ tmp = dma_fence_get_stub();
+ goto return_tmp;
+ }
+
+ if (count == 1) {
+ tmp = array[0];
+ goto return_tmp;
+ }
+
+ result = dma_fence_array_create(count, array,
+ dma_fence_context_alloc(1),
+ 1, false);
+ if (!result) {
+ tmp = NULL;
+ goto return_tmp;
+ }
+ return &result->base;
+
+return_tmp:
+ kfree(array);
+ return tmp;
+}
+EXPORT_SYMBOL_GPL(__dma_fence_merge);
diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c b/drivers/dma-buf/st-dma-fence-unwrap.c
index 59628add93f5..23ab134417ed 100644
--- a/drivers/dma-buf/st-dma-fence-unwrap.c
+++ b/drivers/dma-buf/st-dma-fence-unwrap.c
@@ -240,6 +240,52 @@ static int unwrap_chain_array(void *arg)
return err;
}
+static int unwrap_merge(void *arg)
+{
+ struct dma_fence *fence, *f1, *f2, *f3;
+ struct dma_fence_unwrap iter;
+ int err = 0;
+
+ f1 = mock_fence();
+ if (!f1)
+ return -ENOMEM;
+
+ f2 = mock_fence();
+ if (!f2) {
+ err = -ENOMEM;
+ goto error_put_f1;
+ }
+
+ f3 = dma_fence_merge(f1, f2);
+ if (!f3) {
+ err = -ENOMEM;
+ goto error_put_f2;
+ }
+
+ dma_fence_unwrap_for_each(fence, &iter, f3) {
+ if (fence == f1) {
+ f1 = NULL;
+ } else if (fence == f2) {
+ f2 = NULL;
+ } else {
+ pr_err("Unexpected fence!\n");
+ err = -EINVAL;
+ }
+ }
+
+ if (f1 || f2) {
+ pr_err("Not all fences seen!\n");
+ err = -EINVAL;
+ }
+
+ dma_fence_put(f3);
+error_put_f2:
+ dma_fence_put(f2);
+error_put_f1:
+ dma_fence_put(f1);
+ return err;
+}
+
int dma_fence_unwrap(void)
{
static const struct subtest tests[] = {
@@ -247,6 +293,7 @@ int dma_fence_unwrap(void)
SUBTEST(unwrap_array),
SUBTEST(unwrap_chain),
SUBTEST(unwrap_chain_array),
+ SUBTEST(unwrap_merge),
};
return subtests(tests, NULL);
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
index 0fe564539166..fe149d7e3ce2 100644
--- a/drivers/dma-buf/sync_file.c
+++ b/drivers/dma-buf/sync_file.c
@@ -146,50 +146,6 @@ char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
return buf;
}
-static int sync_file_set_fence(struct sync_file *sync_file,
- struct dma_fence **fences, int num_fences)
-{
- struct dma_fence_array *array;
-
- /*
- * The reference for the fences in the new sync_file and held
- * in add_fence() during the merge procedure, so for num_fences == 1
- * 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 == 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),
- 1, false);
- if (!array)
- return -ENOMEM;
-
- sync_file->fence = &array->base;
- }
-
- return 0;
-}
-
-static void add_fence(struct dma_fence **fences,
- int *i, struct dma_fence *fence)
-{
- fences[*i] = fence;
-
- if (!dma_fence_is_signaled(fence)) {
- dma_fence_get(fence);
- (*i)++;
- }
-}
-
/**
* sync_file_merge() - merge two sync_files
* @name: name of new fence
@@ -203,84 +159,21 @@ static void add_fence(struct dma_fence **fences,
static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
struct sync_file *b)
{
- struct dma_fence *a_fence, *b_fence, **fences;
- struct dma_fence_unwrap a_iter, b_iter;
- unsigned int index, num_fences;
struct sync_file *sync_file;
+ struct dma_fence *fence;
sync_file = sync_file_alloc();
if (!sync_file)
return NULL;
- num_fences = 0;
- dma_fence_unwrap_for_each(a_fence, &a_iter, a->fence)
- ++num_fences;
- dma_fence_unwrap_for_each(b_fence, &b_iter, b->fence)
- ++num_fences;
-
- if (num_fences > INT_MAX)
- goto err_free_sync_file;
-
- fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL);
- if (!fences)
- goto err_free_sync_file;
-
- /*
- * We can't guarantee that fences in both a and b are ordered, but it is
- * still quite likely.
- *
- * So attempt to order the fences as we pass over them and merge fences
- * with the same context.
- */
-
- index = 0;
- for (a_fence = dma_fence_unwrap_first(a->fence, &a_iter),
- b_fence = dma_fence_unwrap_first(b->fence, &b_iter);
- a_fence || b_fence; ) {
-
- if (!b_fence) {
- add_fence(fences, &index, a_fence);
- a_fence = dma_fence_unwrap_next(&a_iter);
-
- } else if (!a_fence) {
- add_fence(fences, &index, b_fence);
- b_fence = dma_fence_unwrap_next(&b_iter);
-
- } else if (a_fence->context < b_fence->context) {
- add_fence(fences, &index, a_fence);
- a_fence = dma_fence_unwrap_next(&a_iter);
-
- } else if (b_fence->context < a_fence->context) {
- add_fence(fences, &index, b_fence);
- b_fence = dma_fence_unwrap_next(&b_iter);
-
- } else if (__dma_fence_is_later(a_fence->seqno, b_fence->seqno,
- a_fence->ops)) {
- add_fence(fences, &index, a_fence);
- a_fence = dma_fence_unwrap_next(&a_iter);
- b_fence = dma_fence_unwrap_next(&b_iter);
-
- } else {
- add_fence(fences, &index, b_fence);
- a_fence = dma_fence_unwrap_next(&a_iter);
- b_fence = dma_fence_unwrap_next(&b_iter);
- }
+ fence = dma_fence_merge(a->fence, b->fence);
+ if (!fence) {
+ fput(sync_file->file);
+ return NULL;
}
-
- if (sync_file_set_fence(sync_file, fences, index) < 0)
- goto err_put_fences;
-
+ sync_file->fence = fence;
strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
return sync_file;
-
-err_put_fences:
- while (index)
- dma_fence_put(fences[--index]);
- kfree(fences);
-
-err_free_sync_file:
- fput(sync_file->file);
- return NULL;
}
static int sync_file_release(struct inode *inode, struct file *file)
diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
index e7c219da4ed7..7c0fab318301 100644
--- a/include/linux/dma-fence-unwrap.h
+++ b/include/linux/dma-fence-unwrap.h
@@ -48,4 +48,28 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
for (fence = dma_fence_unwrap_first(head, cursor); fence; \
fence = dma_fence_unwrap_next(cursor))
+struct dma_fence *__dma_fence_merge(unsigned int num_fences,
+ struct dma_fence **fences,
+ struct dma_fence_unwrap *cursors);
+
+/**
+ * dma_fence_merge - unwrap and merge fences
+ *
+ * All fences given as parameters are unwrapped and merged back together as flat
+ * dma_fence_array. Useful if multiple containers need to be merged together.
+ *
+ * Implemented as a macro to allocate the necessary arrays on the stack and
+ * account the stack frame size to the caller.
+ *
+ * Returns NULL on memory allocation failure, a dma_fence object representing
+ * all the given fences otherwise.
+ */
+#define dma_fence_merge(...) \
+ ({ \
+ struct dma_fence *__f[] = { __VA_ARGS__ }; \
+ struct dma_fence_unwrap __c[ARRAY_SIZE(__f)]; \
+ \
+ __dma_fence_merge(ARRAY_SIZE(__f), __f, __c); \
+ })
+
#endif
--
2.25.1
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