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dma-debug: add hash functions for dma_debug_entries 

Impact: implement necessary functions for the core hash

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
This commit is contained in:
Joerg Roedel 2009-01-09 12:34:49 +01:00
parent f2f45e5f3c
commit 30dfa90cc8
1 changed files with 101 additions and 0 deletions
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101
lib/dma-debug.c
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@ -18,9 +18,14 @@
*/
#include <linux/dma-debug.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/list.h>
#define HASH_SIZE 1024ULL
#define HASH_FN_SHIFT 13
#define HASH_FN_MASK (HASH_SIZE - 1)
enum {
dma_debug_single,
dma_debug_page,
@ -40,3 +45,99 @@ struct dma_debug_entry {
int sg_mapped_ents;
};
struct hash_bucket {
struct list_head list;
spinlock_t lock;
} __cacheline_aligned_in_smp;
/* Hash list to save the allocated dma addresses */
static struct hash_bucket dma_entry_hash[HASH_SIZE];
/*
* Hash related functions
*
* Every DMA-API request is saved into a struct dma_debug_entry. To
* have quick access to these structs they are stored into a hash.
*/
static int hash_fn(struct dma_debug_entry *entry)
{
/*
* Hash function is based on the dma address.
* We use bits 20-27 here as the index into the hash
*/
return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
}
/*
* Request exclusive access to a hash bucket for a given dma_debug_entry.
*/
static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
unsigned long *flags)
{
int idx = hash_fn(entry);
unsigned long __flags;
spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
*flags = __flags;
return &dma_entry_hash[idx];
}
/*
* Give up exclusive access to the hash bucket
*/
static void put_hash_bucket(struct hash_bucket *bucket,
unsigned long *flags)
{
unsigned long __flags = *flags;
spin_unlock_irqrestore(&bucket->lock, __flags);
}
/*
* Search a given entry in the hash bucket list
*/
static struct dma_debug_entry *hash_bucket_find(struct hash_bucket *bucket,
struct dma_debug_entry *ref)
{
struct dma_debug_entry *entry;
list_for_each_entry(entry, &bucket->list, list) {
if ((entry->dev_addr == ref->dev_addr) &&
(entry->dev == ref->dev))
return entry;
}
return NULL;
}
/*
* Add an entry to a hash bucket
*/
static void hash_bucket_add(struct hash_bucket *bucket,
struct dma_debug_entry *entry)
{
list_add_tail(&entry->list, &bucket->list);
}
/*
* Remove entry from a hash bucket list
*/
static void hash_bucket_del(struct dma_debug_entry *entry)
{
list_del(&entry->list);
}
/*
* Wrapper function for adding an entry to the hash.
* This function takes care of locking itself.
*/
static void add_dma_entry(struct dma_debug_entry *entry)
{
struct hash_bucket *bucket;
unsigned long flags;
bucket = get_hash_bucket(entry, &flags);
hash_bucket_add(bucket, entry);
put_hash_bucket(bucket, &flags);
}