dma-debug: add hash functions for dma_debug_entries (30dfa90c) · Commits · e / devices / android_kernel_fairphone_FP5

lib/dma-debug.c

+101 −0

Original line number	Diff line number	Diff line
		@@ -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);
		}