Commit e6a1a89d authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by Ingo Molnar
Browse files

dma-debug: add dma_debug_resize_entries() to adjust the number of dma_debug_entries 



We use a static value for the number of dma_debug_entries. It can be
overwritten by a kernel command line option.

Some IOMMUs (e.g. GART) can't set an appropriate value by a kernel
command line option because they can't know such value until they
finish initializing up their hardware.

This patch adds dma_debug_resize_entries() enables IOMMUs to adjust
the number of dma_debug_entries anytime.

Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
Cc: fujita.tomonori@lab.ntt.co.jp
Cc: akpm@linux-foundation.org
LKML-Reference: <20090415182234R.fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 7e05575c

include/linux/dma-debug.h

+7 −0
Original line number Diff line number Diff line
@@ -32,6 +32,8 @@ extern void dma_debug_add_bus(struct bus_type *bus); 


extern void dma_debug_init(u32 num_entries);



extern int dma_debug_resize_entries(u32 num_entries);



extern void debug_dma_map_page(struct device *dev, struct page *page,

			       size_t offset, size_t size,

			       int direction, dma_addr_t dma_addr,
@@ -91,6 +93,11 @@ static inline void dma_debug_init(u32 num_entries) 
{

}



static inline int dma_debug_resize_entries(u32 num_entries)

{

	return 0;

}



static inline void debug_dma_map_page(struct device *dev, struct page *page,

				      size_t offset, size_t size,

				      int direction, dma_addr_t dma_addr,

lib/dma-debug.c

+66 −6
Original line number Diff line number Diff line
@@ -85,6 +85,7 @@ static u32 show_num_errors = 1; 


static u32 num_free_entries;

static u32 min_free_entries;

static u32 nr_total_entries;



/* number of preallocated entries requested by kernel cmdline */

static u32 req_entries;
@@ -257,6 +258,21 @@ static void add_dma_entry(struct dma_debug_entry *entry) 
	put_hash_bucket(bucket, &flags);

}



static struct dma_debug_entry *__dma_entry_alloc(void)

{

	struct dma_debug_entry *entry;



	entry = list_entry(free_entries.next, struct dma_debug_entry, list);

	list_del(&entry->list);

	memset(entry, 0, sizeof(*entry));



	num_free_entries -= 1;

	if (num_free_entries < min_free_entries)

		min_free_entries = num_free_entries;



	return entry;

}



/* struct dma_entry allocator

 *

 * The next two functions implement the allocator for
@@ -276,9 +292,7 @@ static struct dma_debug_entry *dma_entry_alloc(void) 
		goto out;

	}



	entry = list_entry(free_entries.next, struct dma_debug_entry, list);

	list_del(&entry->list);

	memset(entry, 0, sizeof(*entry));

	entry = __dma_entry_alloc();



#ifdef CONFIG_STACKTRACE

	entry->stacktrace.max_entries = DMA_DEBUG_STACKTRACE_ENTRIES;
@@ -286,9 +300,6 @@ static struct dma_debug_entry *dma_entry_alloc(void) 
	entry->stacktrace.skip = 2;

	save_stack_trace(&entry->stacktrace);

#endif

	num_free_entries -= 1;

	if (num_free_entries < min_free_entries)

		min_free_entries = num_free_entries;



out:

	spin_unlock_irqrestore(&free_entries_lock, flags);
@@ -310,6 +321,53 @@ static void dma_entry_free(struct dma_debug_entry *entry) 
	spin_unlock_irqrestore(&free_entries_lock, flags);

}



int dma_debug_resize_entries(u32 num_entries)

{

	int i, delta, ret = 0;

	unsigned long flags;

	struct dma_debug_entry *entry;

	LIST_HEAD(tmp);



	spin_lock_irqsave(&free_entries_lock, flags);



	if (nr_total_entries < num_entries) {

		delta = num_entries - nr_total_entries;



		spin_unlock_irqrestore(&free_entries_lock, flags);



		for (i = 0; i < delta; i++) {

			entry = kzalloc(sizeof(*entry), GFP_KERNEL);

			if (!entry)

				break;



			list_add_tail(&entry->list, &tmp);

		}



		spin_lock_irqsave(&free_entries_lock, flags);



		list_splice(&tmp, &free_entries);

		nr_total_entries += i;

		num_free_entries += i;

	} else {

		delta = nr_total_entries - num_entries;



		for (i = 0; i < delta && !list_empty(&free_entries); i++) {

			entry = __dma_entry_alloc();

			kfree(entry);

		}



		nr_total_entries -= i;

	}



	if (nr_total_entries != num_entries)

		ret = 1;



	spin_unlock_irqrestore(&free_entries_lock, flags);



	return ret;

}

EXPORT_SYMBOL(dma_debug_resize_entries);



/*

 * DMA-API debugging init code

 *
@@ -490,6 +548,8 @@ void dma_debug_init(u32 num_entries) 
		return;

	}



	nr_total_entries = num_free_entries;



	printk(KERN_INFO "DMA-API: debugging enabled by kernel config\n");

}

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