Commit f45f57cc authored by Christian König's avatar Christian König
Browse files

dma-buf: stop using the dmabuf->lock so much v2 



The attachment list is now protected by the dma_resv object.

Stop holding the dma_buf->lock while calling ->attach/->detach,
this allows for concurrent attach/detach operations.

v2: cleanup commit message and locking in _debug_show()

Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Reviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/336790
parent 15fd552d

drivers/dma-buf/dma-buf.c

+2 −16
Original line number Diff line number Diff line
@@ -685,8 +685,6 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev, 
	attach->dmabuf = dmabuf;

	attach->dynamic_mapping = dynamic_mapping;



	mutex_lock(&dmabuf->lock);



	if (dmabuf->ops->attach) {

		ret = dmabuf->ops->attach(dmabuf, attach);

		if (ret)
@@ -696,8 +694,6 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev, 
	list_add(&attach->node, &dmabuf->attachments);

	dma_resv_unlock(dmabuf->resv);



	mutex_unlock(&dmabuf->lock);



	/* When either the importer or the exporter can't handle dynamic

	 * mappings we cache the mapping here to avoid issues with the

	 * reservation object lock.
@@ -726,7 +722,6 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev, 


err_attach:

	kfree(attach);

	mutex_unlock(&dmabuf->lock);

	return ERR_PTR(ret);



err_unlock:
@@ -776,14 +771,12 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach) 
			dma_resv_unlock(attach->dmabuf->resv);

	}



	mutex_lock(&dmabuf->lock);

	dma_resv_lock(dmabuf->resv, NULL);

	list_del(&attach->node);

	dma_resv_unlock(dmabuf->resv);

	if (dmabuf->ops->detach)

		dmabuf->ops->detach(dmabuf, attach);



	mutex_unlock(&dmabuf->lock);

	kfree(attach);

}

EXPORT_SYMBOL_GPL(dma_buf_detach);
@@ -1248,13 +1241,9 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) 


	list_for_each_entry(buf_obj, &db_list.head, list_node) {



		ret = mutex_lock_interruptible(&buf_obj->lock);

		if (ret)

			goto error_unlock_list;



		ret = dma_resv_lock_interruptible(buf_obj->resv, NULL);

		if (ret)

			goto error_unlock_buf;

			goto error_unlock;



		seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",

				buf_obj->size,
@@ -1307,7 +1296,6 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) 


		count++;

		size += buf_obj->size;

		mutex_unlock(&buf_obj->lock);

	}



	seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
@@ -1315,9 +1303,7 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) 
	mutex_unlock(&db_list.lock);

	return 0;



error_unlock_buf:

	mutex_unlock(&buf_obj->lock);

error_unlock_list:

error_unlock:

	mutex_unlock(&db_list.lock);

	return ret;

}

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