dma-buf: Remove obsoleted internal lock

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.

Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221017172229.42269-22-dmitry.osipenko@collabora.com

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index f1d968e..7663c4e 100644 (file)
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -657,7 +657,6 @@ 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, 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);
 
@@ -1583,13 +1579,11 @@ 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 f11b5bb..6fa8d4e 100644 (file)
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -327,15 +327,6 @@ struct dma_buf {
        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:
         *
         * Used internally to refcnt the vmaps returned by dma_buf_vmap().