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>

2 files changed, 62 insertions, 0 deletions

diff --git a/include/linux/dma-debug.h b/include/linux/dma-debug.h
index 46a11c10da04..e851d23e91eb 100644
--- a/include/linux/dma-debug.h
+++ b/include/linux/dma-debug.h
@@ -24,9 +24,12 @@
 
 struct device;
 struct scatterlist;
+struct bus_type;
 
 #ifdef CONFIG_DMA_API_DEBUG
 
+extern void dma_debug_add_bus(struct bus_type *bus);
+
 extern void dma_debug_init(u32 num_entries);
 
 extern void debug_dma_map_page(struct device *dev, struct page *page,
@@ -80,6 +83,10 @@ extern void debug_dma_dump_mappings(struct device *dev);
 
 #else /* CONFIG_DMA_API_DEBUG */
 
+void dma_debug_add_bus(struct bus_type *bus)
+{
+}
+
 static inline void dma_debug_init(u32 num_entries)
 {
 }
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.