dmaengine: centralize channel allocation, introduce dma_find_channel
[linux-2.6.git] / crypto / async_tx / async_tx.c
index 8cfac18..b88bb1f 100644 (file)
@@ -38,25 +38,10 @@ static struct dma_client async_tx_dma = {
 };
 
 /**
- * dma_cap_mask_all - enable iteration over all operation types
- */
-static dma_cap_mask_t dma_cap_mask_all;
-
-/**
- * chan_ref_percpu - tracks channel allocations per core/opertion
- */
-struct chan_ref_percpu {
-       struct dma_chan_ref *ref;
-};
-
-static int channel_table_initialized;
-static struct chan_ref_percpu *channel_table[DMA_TX_TYPE_END];
-
-/**
  * async_tx_lock - protect modification of async_tx_master_list and serialize
  *     rebalance operations
  */
-static spinlock_t async_tx_lock;
+static DEFINE_SPINLOCK(async_tx_lock);
 
 static LIST_HEAD(async_tx_master_list);
 
@@ -89,85 +74,6 @@ init_dma_chan_ref(struct dma_chan_ref *ref, struct dma_chan *chan)
        atomic_set(&ref->count, 0);
 }
 
-/**
- * get_chan_ref_by_cap - returns the nth channel of the given capability
- *     defaults to returning the channel with the desired capability and the
- *     lowest reference count if the index can not be satisfied
- * @cap: capability to match
- * @index: nth channel desired, passing -1 has the effect of forcing the
- *  default return value
- */
-static struct dma_chan_ref *
-get_chan_ref_by_cap(enum dma_transaction_type cap, int index)
-{
-       struct dma_chan_ref *ret_ref = NULL, *min_ref = NULL, *ref;
-
-       rcu_read_lock();
-       list_for_each_entry_rcu(ref, &async_tx_master_list, node)
-               if (dma_has_cap(cap, ref->chan->device->cap_mask)) {
-                       if (!min_ref)
-                               min_ref = ref;
-                       else if (atomic_read(&ref->count) <
-                               atomic_read(&min_ref->count))
-                               min_ref = ref;
-
-                       if (index-- == 0) {
-                               ret_ref = ref;
-                               break;
-                       }
-               }
-       rcu_read_unlock();
-
-       if (!ret_ref)
-               ret_ref = min_ref;
-
-       if (ret_ref)
-               atomic_inc(&ret_ref->count);
-
-       return ret_ref;
-}
-
-/**
- * async_tx_rebalance - redistribute the available channels, optimize
- * for cpu isolation in the SMP case, and opertaion isolation in the
- * uniprocessor case
- */
-static void async_tx_rebalance(void)
-{
-       int cpu, cap, cpu_idx = 0;
-       unsigned long flags;
-
-       if (!channel_table_initialized)
-               return;
-
-       spin_lock_irqsave(&async_tx_lock, flags);
-
-       /* undo the last distribution */
-       for_each_dma_cap_mask(cap, dma_cap_mask_all)
-               for_each_possible_cpu(cpu) {
-                       struct dma_chan_ref *ref =
-                               per_cpu_ptr(channel_table[cap], cpu)->ref;
-                       if (ref) {
-                               atomic_set(&ref->count, 0);
-                               per_cpu_ptr(channel_table[cap], cpu)->ref =
-                                                                       NULL;
-                       }
-               }
-
-       for_each_dma_cap_mask(cap, dma_cap_mask_all)
-               for_each_online_cpu(cpu) {
-                       struct dma_chan_ref *new;
-                       if (NR_CPUS > 1)
-                               new = get_chan_ref_by_cap(cap, cpu_idx++);
-                       else
-                               new = get_chan_ref_by_cap(cap, -1);
-
-                       per_cpu_ptr(channel_table[cap], cpu)->ref = new;
-               }
-
-       spin_unlock_irqrestore(&async_tx_lock, flags);
-}
-
 static enum dma_state_client
 dma_channel_add_remove(struct dma_client *client,
        struct dma_chan *chan, enum dma_state state)
@@ -198,8 +104,6 @@ dma_channel_add_remove(struct dma_client *client,
                /* add the channel to the generic management list */
                master_ref = kmalloc(sizeof(*master_ref), GFP_KERNEL);
                if (master_ref) {
-                       /* keep a reference until async_tx is unloaded */
-                       dma_chan_get(chan);
                        init_dma_chan_ref(master_ref, chan);
                        spin_lock_irqsave(&async_tx_lock, flags);
                        list_add_tail_rcu(&master_ref->node,
@@ -213,16 +117,12 @@ dma_channel_add_remove(struct dma_client *client,
                                " (-ENOMEM)\n");
                        return 0;
                }
-
-               async_tx_rebalance();
                break;
        case DMA_RESOURCE_REMOVED:
                found = 0;
                spin_lock_irqsave(&async_tx_lock, flags);
                list_for_each_entry(ref, &async_tx_master_list, node)
                        if (ref->chan == chan) {
-                               /* permit backing devices to go away */
-                               dma_chan_put(ref->chan);
                                list_del_rcu(&ref->node);
                                call_rcu(&ref->rcu, free_dma_chan_ref);
                                found = 1;
@@ -237,8 +137,6 @@ dma_channel_add_remove(struct dma_client *client,
                        ack = DMA_ACK;
                else
                        break;
-
-               async_tx_rebalance();
                break;
        case DMA_RESOURCE_SUSPEND:
        case DMA_RESOURCE_RESUME:
@@ -252,51 +150,18 @@ dma_channel_add_remove(struct dma_client *client,
        return ack;
 }
 
-static int __init
-async_tx_init(void)
+static int __init async_tx_init(void)
 {
-       enum dma_transaction_type cap;
-
-       spin_lock_init(&async_tx_lock);
-       bitmap_fill(dma_cap_mask_all.bits, DMA_TX_TYPE_END);
-
-       /* an interrupt will never be an explicit operation type.
-        * clearing this bit prevents allocation to a slot in 'channel_table'
-        */
-       clear_bit(DMA_INTERRUPT, dma_cap_mask_all.bits);
-
-       for_each_dma_cap_mask(cap, dma_cap_mask_all) {
-               channel_table[cap] = alloc_percpu(struct chan_ref_percpu);
-               if (!channel_table[cap])
-                       goto err;
-       }
-
-       channel_table_initialized = 1;
        dma_async_client_register(&async_tx_dma);
        dma_async_client_chan_request(&async_tx_dma);
 
        printk(KERN_INFO "async_tx: api initialized (async)\n");
 
        return 0;
-err:
-       printk(KERN_ERR "async_tx: initialization failure\n");
-
-       while (--cap >= 0)
-               free_percpu(channel_table[cap]);
-
-       return 1;
 }
 
 static void __exit async_tx_exit(void)
 {
-       enum dma_transaction_type cap;
-
-       channel_table_initialized = 0;
-
-       for_each_dma_cap_mask(cap, dma_cap_mask_all)
-               if (channel_table[cap])
-                       free_percpu(channel_table[cap]);
-
        dma_async_client_unregister(&async_tx_dma);
 }
 
@@ -312,16 +177,9 @@ __async_tx_find_channel(struct dma_async_tx_descriptor *depend_tx,
 {
        /* see if we can keep the chain on one channel */
        if (depend_tx &&
-               dma_has_cap(tx_type, depend_tx->chan->device->cap_mask))
+           dma_has_cap(tx_type, depend_tx->chan->device->cap_mask))
                return depend_tx->chan;
-       else if (likely(channel_table_initialized)) {
-               struct dma_chan_ref *ref;
-               int cpu = get_cpu();
-               ref = per_cpu_ptr(channel_table[tx_type], cpu)->ref;
-               put_cpu();
-               return ref ? ref->chan : NULL;
-       } else
-               return NULL;
+       return dma_find_channel(tx_type);
 }
 EXPORT_SYMBOL_GPL(__async_tx_find_channel);
 #else