dma-debug: add a check dma memory leaks

Impact: allow architectures to monitor busses for dma mem leakage

This patch adds checking code to detect if a device has pending DMA
operations when it is about to be unbound from its device driver.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 6022eb4a0cd0..9a350b414a50 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -400,6 +400,61 @@ out_err:
 	return -ENOMEM;
 }
 
+static int device_dma_allocations(struct device *dev)
+{
+	struct dma_debug_entry *entry;
+	unsigned long flags;
+	int count = 0, i;
+
+	for (i = 0; i < HASH_SIZE; ++i) {
+		spin_lock_irqsave(&dma_entry_hash[i].lock, flags);
+		list_for_each_entry(entry, &dma_entry_hash[i].list, list) {
+			if (entry->dev == dev)
+				count += 1;
+		}
+		spin_unlock_irqrestore(&dma_entry_hash[i].lock, flags);
+	}
+
+	return count;
+}
+
+static int dma_debug_device_change(struct notifier_block *nb,
+				    unsigned long action, void *data)
+{
+	struct device *dev = data;
+	int count;
+
+
+	switch (action) {
+	case BUS_NOTIFY_UNBIND_DRIVER:
+		count = device_dma_allocations(dev);
+		if (count == 0)
+			break;
+		err_printk(dev, NULL, "DMA-API: device driver has pending "
+				"DMA allocations while released from device "
+				"[count=%d]\n", count);
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+void dma_debug_add_bus(struct bus_type *bus)
+{
+	struct notifier_block *nb;
+
+	nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
+	if (nb == NULL) {
+		printk(KERN_ERR "dma_debug_add_bus: out of memory\n");
+		return;
+	}
+
+	nb->notifier_call = dma_debug_device_change;
+
+	bus_register_notifier(bus, nb);
+}
 
 /*
  * Let the architectures decide how many entries should be preallocated.