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    SubjectRe: [PATCH v3 9/9] dma-buf: Remove internal lock
    From
    Am 24.08.22 um 12:22 schrieb Dmitry Osipenko:
    > The internal dma-buf lock isn't needed anymore because the updated
    > locking specification claims that dma-buf reservation must be locked
    > by importers, and thus, the internal data is already protected by the
    > reservation lock. Remove the obsoleted internal lock.
    >
    > Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>

    Reviewed-by: Christian König <christian.koenig@amd.com>

    > ---
    > drivers/dma-buf/dma-buf.c | 14 ++++----------
    > include/linux/dma-buf.h | 9 ---------
    > 2 files changed, 4 insertions(+), 19 deletions(-)
    >
    > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
    > index 696d132b02f4..a0406254f0ae 100644
    > --- a/drivers/dma-buf/dma-buf.c
    > +++ b/drivers/dma-buf/dma-buf.c
    > @@ -656,7 +656,6 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
    >
    > dmabuf->file = file;
    >
    > - mutex_init(&dmabuf->lock);
    > INIT_LIST_HEAD(&dmabuf->attachments);
    >
    > mutex_lock(&db_list.lock);
    > @@ -1503,7 +1502,7 @@ EXPORT_SYMBOL_NS_GPL(dma_buf_mmap_unlocked, DMA_BUF);
    > int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
    > {
    > struct iosys_map ptr;
    > - int ret = 0;
    > + int ret;
    >
    > iosys_map_clear(map);
    >
    > @@ -1515,28 +1514,25 @@ int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
    > if (!dmabuf->ops->vmap)
    > return -EINVAL;
    >
    > - mutex_lock(&dmabuf->lock);
    > if (dmabuf->vmapping_counter) {
    > dmabuf->vmapping_counter++;
    > BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
    > *map = dmabuf->vmap_ptr;
    > - goto out_unlock;
    > + return 0;
    > }
    >
    > BUG_ON(iosys_map_is_set(&dmabuf->vmap_ptr));
    >
    > ret = dmabuf->ops->vmap(dmabuf, &ptr);
    > if (WARN_ON_ONCE(ret))
    > - goto out_unlock;
    > + return ret;
    >
    > dmabuf->vmap_ptr = ptr;
    > dmabuf->vmapping_counter = 1;
    >
    > *map = dmabuf->vmap_ptr;
    >
    > -out_unlock:
    > - mutex_unlock(&dmabuf->lock);
    > - return ret;
    > + return 0;
    > }
    > EXPORT_SYMBOL_NS_GPL(dma_buf_vmap, DMA_BUF);
    >
    > @@ -1578,13 +1574,11 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)
    > BUG_ON(dmabuf->vmapping_counter == 0);
    > BUG_ON(!iosys_map_is_equal(&dmabuf->vmap_ptr, map));
    >
    > - mutex_lock(&dmabuf->lock);
    > if (--dmabuf->vmapping_counter == 0) {
    > if (dmabuf->ops->vunmap)
    > dmabuf->ops->vunmap(dmabuf, map);
    > iosys_map_clear(&dmabuf->vmap_ptr);
    > }
    > - mutex_unlock(&dmabuf->lock);
    > }
    > EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap, DMA_BUF);
    >
    > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
    > index d48d534dc55c..aed6695bbb50 100644
    > --- a/include/linux/dma-buf.h
    > +++ b/include/linux/dma-buf.h
    > @@ -326,15 +326,6 @@ struct dma_buf {
    > /** @ops: dma_buf_ops associated with this buffer object. */
    > const struct dma_buf_ops *ops;
    >
    > - /**
    > - * @lock:
    > - *
    > - * Used internally to serialize list manipulation, attach/detach and
    > - * vmap/unmap. Note that in many cases this is superseeded by
    > - * dma_resv_lock() on @resv.
    > - */
    > - struct mutex lock;
    > -
    > /**
    > * @vmapping_counter:
    > *

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