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    SubjectRe: [PATCH v4 3/7] dma-buf: heaps: restricted_heap: Add private heap ops
    On Fri, Jan 12, 2024 at 05:20:10PM +0800, Yong Wu wrote:
    > Add "struct restricted_heap_ops". For the restricted memory, totally there
    > are two steps:
    > a) memory_alloc: Allocate the buffer in kernel;
    > b) memory_restrict: Restrict/Protect/Secure that buffer.
    > The memory_alloc is mandatory while memory_restrict is optinal since it may
    >
    s/optinal/optional/

    > be part of memory_alloc.
    >
    > Signed-off-by: Yong Wu <yong.wu@mediatek.com>
    > ---
    > drivers/dma-buf/heaps/restricted_heap.c | 41 ++++++++++++++++++++++++-
    > drivers/dma-buf/heaps/restricted_heap.h | 12 ++++++++
    > 2 files changed, 52 insertions(+), 1 deletion(-)
    >
    > diff --git a/drivers/dma-buf/heaps/restricted_heap.c b/drivers/dma-buf/heaps/restricted_heap.c
    > index fd7c82abd42e..8c266a0f6192 100644
    > --- a/drivers/dma-buf/heaps/restricted_heap.c
    > +++ b/drivers/dma-buf/heaps/restricted_heap.c
    > @@ -12,10 +12,44 @@
    >
    > #include "restricted_heap.h"
    >
    > +static int
    > +restricted_heap_memory_allocate(struct restricted_heap *heap, struct restricted_buffer *buf)
    > +{
    > + const struct restricted_heap_ops *ops = heap->ops;
    > + int ret;
    > +
    > + ret = ops->memory_alloc(heap, buf);
    > + if (ret)
    > + return ret;
    > +
    > + if (ops->memory_restrict) {
    > + ret = ops->memory_restrict(heap, buf);
    > + if (ret)
    > + goto memory_free;
    > + }
    > + return 0;
    > +
    > +memory_free:
    > + ops->memory_free(heap, buf);
    > + return ret;
    > +}
    > +
    > +static void
    > +restricted_heap_memory_free(struct restricted_heap *heap, struct restricted_buffer *buf)
    > +{
    > + const struct restricted_heap_ops *ops = heap->ops;
    > +
    > + if (ops->memory_unrestrict)
    > + ops->memory_unrestrict(heap, buf);
    > +
    > + ops->memory_free(heap, buf);
    > +}
    > +
    > static struct dma_buf *
    > restricted_heap_allocate(struct dma_heap *heap, unsigned long size,
    > unsigned long fd_flags, unsigned long heap_flags)
    > {
    > + struct restricted_heap *restricted_heap = dma_heap_get_drvdata(heap);
    > struct restricted_buffer *restricted_buf;
    > DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
    > struct dma_buf *dmabuf;
    > @@ -28,6 +62,9 @@ restricted_heap_allocate(struct dma_heap *heap, unsigned long size,
    > restricted_buf->size = ALIGN(size, PAGE_SIZE);
    > restricted_buf->heap = heap;
    >
    > + ret = restricted_heap_memory_allocate(restricted_heap, restricted_buf);
    >
    Can we guarantee that "restricted_heap" here isn't NULL (i.e., heap->priv). If
    not perhaps we should consider adding a check for NULL in the
    restricted_heap_memory_allocate() function?

    > + if (ret)
    > + goto err_free_buf;
    > exp_info.exp_name = dma_heap_get_name(heap);
    > exp_info.size = restricted_buf->size;
    > exp_info.flags = fd_flags;
    > @@ -36,11 +73,13 @@ restricted_heap_allocate(struct dma_heap *heap, unsigned long size,
    > dmabuf = dma_buf_export(&exp_info);
    > if (IS_ERR(dmabuf)) {
    > ret = PTR_ERR(dmabuf);
    > - goto err_free_buf;
    > + goto err_free_restricted_mem;
    > }
    >
    > return dmabuf;
    >
    > +err_free_restricted_mem:
    > + restricted_heap_memory_free(restricted_heap, restricted_buf);
    > err_free_buf:
    > kfree(restricted_buf);
    > return ERR_PTR(ret);
    > diff --git a/drivers/dma-buf/heaps/restricted_heap.h b/drivers/dma-buf/heaps/restricted_heap.h
    > index 443028f6ba3b..ddeaf9805708 100644
    > --- a/drivers/dma-buf/heaps/restricted_heap.h
    > +++ b/drivers/dma-buf/heaps/restricted_heap.h
    > @@ -15,6 +15,18 @@ struct restricted_buffer {
    >
    > struct restricted_heap {
    > const char *name;
    > +
    > + const struct restricted_heap_ops *ops;
    > +};
    > +
    > +struct restricted_heap_ops {
    >
    This have the same name as used for the dma_heap_ops in the file
    restricted_heap.c, this might be a little bit confusing, or?

    > + int (*heap_init)(struct restricted_heap *heap);
    > +
    > + int (*memory_alloc)(struct restricted_heap *heap, struct restricted_buffer *buf);
    > + void (*memory_free)(struct restricted_heap *heap, struct restricted_buffer *buf);
    > +
    > + int (*memory_restrict)(struct restricted_heap *heap, struct restricted_buffer *buf);
    > + void (*memory_unrestrict)(struct restricted_heap *heap, struct restricted_buffer *buf);
    >
    Is the prefix "memory_" superfluous here in these ops?

    Also related to a comment on the prior patch. The name here is "heap" for
    restricted_heap, but below you use rstrd_heap. It's the same struct, so I would
    advise to use the same name to avoid confusion when reading the code. As
    mentioned before, I think the name "rheap" would be a good choice.

    > };
    >
    > int restricted_heap_add(struct restricted_heap *rstrd_heap);
    > --
    > 2.25.1
    >

    --
    // Regards
    Joakim

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