midgard/r13p0/kernel/patches/integrate_kds_with_dma_buf.patch

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 9aa618a..30e07ea 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -192,4 +192,12 @@ config DMA_SHARED_BUFFER
 	  APIs extension; the file's descriptor can then be passed on to other
 	  driver.
 
+config DMA_SHARED_BUFFER_USES_KDS
+	bool "Synchronize access to dma_buf with KDS"
+	default n
+	select KDS
+	depends on DMA_SHARED_BUFFER
+	help
+	  This option adds a KDS resource within every dma_buf allocation.
+
 endmenu
diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 20258e1..e4083fd 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -27,6 +27,8 @@
 #include <linux/dma-buf.h>
 #include <linux/anon_inodes.h>
 #include <linux/export.h>
+#include <linux/poll.h>
+#include <linux/sched.h>
 
 static inline int is_dma_buf_file(struct file *);
 
@@ -40,6 +42,8 @@ static int dma_buf_release(struct inode *inode, struct file *file)
 	dmabuf = file->private_data;
 
 	dmabuf->ops->release(dmabuf);
+	kds_callback_term(&dmabuf->kds_cb);
+	kds_resource_term(&dmabuf->kds);
 	kfree(dmabuf);
 	return 0;
 }
@@ -61,9 +65,90 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
 	return dmabuf->ops->mmap(dmabuf, vma);
 }
 
+
+static void dma_buf_kds_cb_fn (void *param1, void *param2)
+{
+	struct kds_resource_set **rset_ptr = param1;
+	struct kds_resource_set *rset = *rset_ptr;
+	wait_queue_head_t *wait_queue = param2;
+
+	kfree(rset_ptr);
+	kds_resource_set_release(&rset);
+	wake_up(wait_queue);
+}
+
+static int dma_buf_kds_check(struct kds_resource *kds,
+                             long unsigned int exclusive, int *poll_ret)
+{
+	/* Synchronous wait with 0 timeout - poll availability */
+	struct kds_resource_set *rset = kds_waitall(1,&exclusive,&kds,0);
+
+	if (IS_ERR(rset))
+		return POLLERR;
+
+	if (rset){
+		kds_resource_set_release(&rset);
+		*poll_ret = POLLIN | POLLRDNORM;
+		if (exclusive)
+			*poll_ret |=  POLLOUT | POLLWRNORM;
+		return 1;
+	}else{
+		return 0;
+	}
+}
+
+static unsigned int dma_buf_poll(struct file *file,
+                                 struct poll_table_struct *wait)
+{
+	struct dma_buf *dmabuf;
+	struct kds_resource *kds;
+	unsigned int ret = 0;
+
+	if (!is_dma_buf_file(file))
+		return POLLERR;
+
+	dmabuf = file->private_data;
+	kds    = &dmabuf->kds;
+
+	if (poll_does_not_wait(wait)){
+		/* Check for exclusive access (superset of shared) first */
+		if(!dma_buf_kds_check(kds, 1ul, &ret))
+			dma_buf_kds_check(kds, 0ul, &ret);
+	}else{
+		int events = poll_requested_events(wait);
+		unsigned long exclusive;
+		wait_queue_head_t *wq;
+		struct kds_resource_set **rset_ptr = kmalloc(sizeof(*rset_ptr), GFP_KERNEL);
+
+		if (!rset_ptr)
+			return POLL_ERR;
+
+		if (events & POLLOUT){
+			wq = &dmabuf->wq_exclusive;
+			exclusive = 1;
+		}else{
+			wq = &dmabuf->wq_shared;
+			exclusive = 0;
+		}
+		poll_wait(file, wq, wait);
+		ret = kds_async_waitall(rset_ptr, KDS_FLAG_LOCKED_WAIT, &dmabuf->kds_cb,
+		                        rset_ptr, wq, 1, &exclusive, &kds);
+
+		if (IS_ERR_VALUE(ret)){
+			ret = POLL_ERR;
+			kfree(rset_ptr);
+		}else{
+			/* Can't allow access until callback */
+			ret = 0;
+		}
+	}
+	return ret;
+}
+
 static const struct file_operations dma_buf_fops = {
 	.release	= dma_buf_release,
 	.mmap		= dma_buf_mmap_internal,
+	.poll		= dma_buf_poll,
 };
 
 /*
@@ -120,6 +205,11 @@ struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
 	mutex_init(&dmabuf->lock);
 	INIT_LIST_HEAD(&dmabuf->attachments);
 
+	init_waitqueue_head(&dmabuf->wq_exclusive);
+	init_waitqueue_head(&dmabuf->wq_shared);
+	kds_resource_init(&dmabuf->kds);
+	kds_callback_init(&dmabuf->kds_cb, 1, dma_buf_kds_cb_fn);
+
 	return dmabuf;
 }
 EXPORT_SYMBOL_GPL(dma_buf_export);
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index eb48f38..6e824d2 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -30,6 +30,8 @@
 #include <linux/list.h>
 #include <linux/dma-mapping.h>
 #include <linux/fs.h>
+#include <linux/kds.h>
+#include <linux/wait.h>
 
 struct device;
 struct dma_buf;
@@ -121,6 +123,10 @@ struct dma_buf {
 	const struct dma_buf_ops *ops;
 	/* mutex to serialize list manipulation and attach/detach */
 	struct mutex lock;
+	struct kds_resource kds;
+	wait_queue_head_t wq_exclusive;
+	wait_queue_head_t wq_shared;
+	struct kds_callback kds_cb;
 	void *priv;
 };
 
@@ -156,6 +162,21 @@ static inline void get_dma_buf(struct dma_buf *dmabuf)
 	get_file(dmabuf->file);
 }
 
+/**
+ * get_dma_buf_kds_resource - get a KDS resource for this dma-buf
+ * @dmabuf:	[in]	pointer to dma_buf
+ *
+ * Returns a KDS resource that represents the dma-buf. This should be used by
+ * drivers to synchronize access to the buffer. Note that the caller should
+ * ensure that a reference to the dma-buf exists from the call to
+ * kds_async_wait until kds_resource_set_release is called.
+ */
+static inline struct kds_resource *
+	get_dma_buf_kds_resource(struct dma_buf *dmabuf)
+{
+	return &dmabuf->kds;
+}
+
 #ifdef CONFIG_DMA_SHARED_BUFFER
 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 							struct device *dev);