Commit 41531c8f authored by Joerg Roedel's avatar Joerg Roedel

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: default avatarJoerg Roedel <>
parent 2e34bde1
......@@ -24,9 +24,12 @@
struct device;
struct scatterlist;
struct bus_type;
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);
void dma_debug_add_bus(struct bus_type *bus)
static inline void dma_debug_init(u32 num_entries)
......@@ -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) {
count = device_dma_allocations(dev);
if (count == 0)
err_printk(dev, NULL, "DMA-API: device driver has pending "
"DMA allocations while released from device "
"[count=%d]\n", count);
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");
nb->notifier_call = dma_debug_device_change;
bus_register_notifier(bus, nb);
* Let the architectures decide how many entries should be preallocated.
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