diff options
| -rw-r--r-- | lib/dma-debug.c | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/lib/dma-debug.c b/lib/dma-debug.c index 31099712328c..5ff7d2e2b60e 100644 --- a/lib/dma-debug.c +++ b/lib/dma-debug.c @@ -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); +} + |