1 files changed, 57 insertions, 0 deletions

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 5ff7d2e2b60e..b60914669656 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -52,6 +52,16 @@ struct hash_bucket {
 
 /* Hash list to save the allocated dma addresses */
 static struct hash_bucket dma_entry_hash[HASH_SIZE];
+/* List of pre-allocated dma_debug_entry's */
+static LIST_HEAD(free_entries);
+/* Lock for the list above */
+static DEFINE_SPINLOCK(free_entries_lock);
+
+/* Global disable flag - will be set in case of an error */
+static bool global_disable __read_mostly;
+
+static u32 num_free_entries;
+static u32 min_free_entries;
 
 /*
  * Hash related functions
@@ -141,3 +151,50 @@ static void add_dma_entry(struct dma_debug_entry *entry)
         put_hash_bucket(bucket, &flags);
 }
 
+/* struct dma_entry allocator
+ *
+ * The next two functions implement the allocator for
+ * struct dma_debug_entries.
+ */
+static struct dma_debug_entry *dma_entry_alloc(void)
+{
+        struct dma_debug_entry *entry = NULL;
+        unsigned long flags;
+
+        spin_lock_irqsave(&free_entries_lock, flags);
+
+        if (list_empty(&free_entries)) {
+                printk(KERN_ERR "DMA-API: debugging out of memory "
+                                "- disabling\n");
+                global_disable = true;
+                goto out;
+        }
+
+        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;
+
+out:
+        spin_unlock_irqrestore(&free_entries_lock, flags);
+
+        return entry;
+}
+
+static void dma_entry_free(struct dma_debug_entry *entry)
+{
+        unsigned long flags;
+
+        /*
+         * add to beginning of the list - this way the entries are
+         * more likely cache hot when they are reallocated.
+         */
+        spin_lock_irqsave(&free_entries_lock, flags);
+        list_add(&entry->list, &free_entries);
+        num_free_entries += 1;
+        spin_unlock_irqrestore(&free_entries_lock, flags);
+}
+