On Fri, Mar 11, 2022 at 12:02:44PM +0100, Christian König wrote:
> The dma_fence_chain containers can show up in sync_files as well resulting in
> warnings that those can't be added to dma_fence_array containers when merging
> multiple sync_files together.
>
> Solve this by using the dma_fence_unwrap iterator to deep dive into the
> contained fences and then add those flatten out into a dma_fence_array.
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
I have no idea why we try to keep fences sorted, but oh well it looks like
the merging is done correctly.
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> ---
> drivers/dma-buf/sync_file.c | 141 +++++++++++++++++++-----------------
> 1 file changed, 73 insertions(+), 68 deletions(-)
>
> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> index 394e6e1e9686..b8dea4ec123b 100644
> --- a/drivers/dma-buf/sync_file.c
> +++ b/drivers/dma-buf/sync_file.c
> @@ -5,6 +5,7 @@
> * Copyright (C) 2012 Google, Inc.
> */
>
> +#include <linux/dma-fence-unwrap.h>
> #include <linux/export.h>
> #include <linux/file.h>
> #include <linux/fs.h>
> @@ -172,20 +173,6 @@ static int sync_file_set_fence(struct sync_file *sync_file,
> return 0;
> }
>
> -static struct dma_fence **get_fences(struct sync_file *sync_file,
> - int *num_fences)
> -{
> - if (dma_fence_is_array(sync_file->fence)) {
> - struct dma_fence_array *array = to_dma_fence_array(sync_file->fence);
> -
> - *num_fences = array->num_fences;
> - return array->fences;
> - }
> -
> - *num_fences = 1;
> - return &sync_file->fence;
> -}
> -
> static void add_fence(struct dma_fence **fences,
> int *i, struct dma_fence *fence)
> {
> @@ -210,86 +197,97 @@ 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 **fences = NULL, **nfences, **a_fences, **b_fences;
> - int i = 0, i_a, i_b, num_fences, a_num_fences, b_num_fences;
>
> sync_file = sync_file_alloc();
> if (!sync_file)
> return NULL;
>
> - a_fences = get_fences(a, &a_num_fences);
> - b_fences = get_fences(b, &b_num_fences);
> - if (a_num_fences > INT_MAX - b_num_fences)
> - goto err;
> + 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;
>
> - num_fences = a_num_fences + b_num_fences;
> + if (num_fences > INT_MAX)
> + goto err_free_sync_file;
>
> fences = kcalloc(num_fences, sizeof(*fences), GFP_KERNEL);
> if (!fences)
> - goto err;
> + goto err_free_sync_file;
>
> /*
> - * Assume sync_file a and b are both ordered and have no
> - * duplicates with the same context.
> + * We can't guarantee that fences in both a and b are ordered, but it is
> + * still quite likely.
> *
> - * If a sync_file can only be created with sync_file_merge
> - * and sync_file_create, this is a reasonable assumption.
> + * So attempt to order the fences as we pass over them and merge fences
> + * with the same context.
> */
> - for (i_a = i_b = 0; i_a < a_num_fences && i_b < b_num_fences; ) {
> - struct dma_fence *pt_a = a_fences[i_a];
> - struct dma_fence *pt_b = b_fences[i_b];
>
> - if (pt_a->context < pt_b->context) {
> - add_fence(fences, &i, pt_a);
> + 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);
>
> - i_a++;
> - } else if (pt_a->context > pt_b->context) {
> - add_fence(fences, &i, pt_b);
> + } 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);
>
> - i_b++;
> } else {
> - if (__dma_fence_is_later(pt_a->seqno, pt_b->seqno,
> - pt_a->ops))
> - add_fence(fences, &i, pt_a);
> - else
> - add_fence(fences, &i, pt_b);
> -
> - i_a++;
> - i_b++;
> + add_fence(fences, &index, b_fence);
> + a_fence = dma_fence_unwrap_next(&a_iter);
> + b_fence = dma_fence_unwrap_next(&b_iter);
> }
> }
>
> - for (; i_a < a_num_fences; i_a++)
> - add_fence(fences, &i, a_fences[i_a]);
> -
> - for (; i_b < b_num_fences; i_b++)
> - add_fence(fences, &i, b_fences[i_b]);
> -
> - if (i == 0)
> - fences[i++] = dma_fence_get(a_fences[0]);
> + if (index == 0)
> + add_fence(fences, &index, dma_fence_get_stub());
>
> - if (num_fences > i) {
> - nfences = krealloc_array(fences, i, sizeof(*fences), GFP_KERNEL);
> - if (!nfences)
> - goto err;
> + if (num_fences > index) {
> + struct dma_fence **tmp;
>
> - fences = nfences;
> + /* 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, i) < 0)
> - goto err;
> + if (sync_file_set_fence(sync_file, fences, index) < 0)
> + goto err_put_fences;
>
> strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
> return sync_file;
>
> -err:
> - while (i)
> - dma_fence_put(fences[--i]);
> +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)
> @@ -398,11 +396,13 @@ static int sync_fill_fence_info(struct dma_fence *fence,
> static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
> unsigned long arg)
> {
> - struct sync_file_info info;
> struct sync_fence_info *fence_info = NULL;
> - struct dma_fence **fences;
> + struct dma_fence_unwrap iter;
> + struct sync_file_info info;
> + unsigned int num_fences;
> + struct dma_fence *fence;
> + int ret;
> __u32 size;
> - int num_fences, ret, i;
>
> if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
> return -EFAULT;
> @@ -410,7 +410,9 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
> if (info.flags || info.pad)
> return -EINVAL;
>
> - fences = get_fences(sync_file, &num_fences);
> + num_fences = 0;
> + dma_fence_unwrap_for_each(fence, &iter, sync_file->fence)
> + ++num_fences;
>
> /*
> * Passing num_fences = 0 means that userspace doesn't want to
> @@ -433,8 +435,11 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
> if (!fence_info)
> return -ENOMEM;
>
> - for (i = 0; i < num_fences; i++) {
> - int status = sync_fill_fence_info(fences[i], &fence_info[i]);
> + num_fences = 0;
> + dma_fence_unwrap_for_each(fence, &iter, sync_file->fence) {
> + int status;
> +
> + status = sync_fill_fence_info(fence, &fence_info[num_fences++]);
> info.status = info.status <= 0 ? info.status : status;
> }
>
> --
> 2.25.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
