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

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 <joerg.roedel@amd.com>
parent 2e34bde1

include/linux/dma-debug.h

+7 −0
Original line number Diff line number Diff line
@@ -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)

{

}

lib/dma-debug.c

+55 −0
Original line number Diff line number Diff line
@@ -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.