dmaengine: replace dma_async_client_register with dmaengine_get

Now that clients no longer need to be notified of channel arrival
dma_async_client_register can simply increment the dmaengine_ref_count.

Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

4 files changed, 11 insertions, 133 deletions

diff --git a/crypto/async_tx/async_tx.c b/crypto/async_tx/async_tx.c
index 2cdf7a0867b7..f21147f3626a 100644
--- a/crypto/async_tx/async_tx.c
+++ b/crypto/async_tx/async_tx.c
@@ -28,120 +28,9 @@
 #include <linux/async_tx.h>
 
 #ifdef CONFIG_DMA_ENGINE
-static enum dma_state_client
-dma_channel_add_remove(struct dma_client *client,
-        struct dma_chan *chan, enum dma_state state);
-
-static struct dma_client async_tx_dma = {
-        .event_callback = dma_channel_add_remove,
-        /* .cap_mask == 0 defaults to all channels */
-};
-
-/**
- * async_tx_lock - protect modification of async_tx_master_list and serialize
- *      rebalance operations
- */
-static DEFINE_SPINLOCK(async_tx_lock);
-
-static LIST_HEAD(async_tx_master_list);
-
-static void
-free_dma_chan_ref(struct rcu_head *rcu)
-{
-        struct dma_chan_ref *ref;
-        ref = container_of(rcu, struct dma_chan_ref, rcu);
-        kfree(ref);
-}
-
-static void
-init_dma_chan_ref(struct dma_chan_ref *ref, struct dma_chan *chan)
-{
-        INIT_LIST_HEAD(&ref->node);
-        INIT_RCU_HEAD(&ref->rcu);
-        ref->chan = chan;
-        atomic_set(&ref->count, 0);
-}
-
-static enum dma_state_client
-dma_channel_add_remove(struct dma_client *client,
-        struct dma_chan *chan, enum dma_state state)
-{
-        unsigned long found, flags;
-        struct dma_chan_ref *master_ref, *ref;
-        enum dma_state_client ack = DMA_DUP; /* default: take no action */
-
-        switch (state) {
-        case DMA_RESOURCE_AVAILABLE:
-                found = 0;
-                rcu_read_lock();
-                list_for_each_entry_rcu(ref, &async_tx_master_list, node)
-                        if (ref->chan == chan) {
-                                found = 1;
-                                break;
-                        }
-                rcu_read_unlock();
-
-                pr_debug("async_tx: dma resource available [%s]\n",
-                        found ? "old" : "new");
-
-                if (!found)
-                        ack = DMA_ACK;
-                else
-                        break;
-
-                /* add the channel to the generic management list */
-                master_ref = kmalloc(sizeof(*master_ref), GFP_KERNEL);
-                if (master_ref) {
-                        init_dma_chan_ref(master_ref, chan);
-                        spin_lock_irqsave(&async_tx_lock, flags);
-                        list_add_tail_rcu(&master_ref->node,
-                                &async_tx_master_list);
-                        spin_unlock_irqrestore(&async_tx_lock,
-                                flags);
-                } else {
-                        printk(KERN_WARNING "async_tx: unable to create"
-                                " new master entry in response to"
-                                " a DMA_RESOURCE_ADDED event"
-                                " (-ENOMEM)\n");
-                        return 0;
-                }
-                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) {
-                                list_del_rcu(&ref->node);
-                                call_rcu(&ref->rcu, free_dma_chan_ref);
-                                found = 1;
-                                break;
-                        }
-                spin_unlock_irqrestore(&async_tx_lock, flags);
-
-                pr_debug("async_tx: dma resource removed [%s]\n",
-                        found ? "ours" : "not ours");
-
-                if (found)
-                        ack = DMA_ACK;
-                else
-                        break;
-                break;
-        case DMA_RESOURCE_SUSPEND:
-        case DMA_RESOURCE_RESUME:
-                printk(KERN_WARNING "async_tx: does not support dma channel"
-                        " suspend/resume\n");
-                break;
-        default:
-                BUG();
-        }
-
-        return ack;
-}
-
 static int __init async_tx_init(void)
 {
-        dma_async_client_register(&async_tx_dma);
-        dma_async_client_chan_request(&async_tx_dma);
+        dmaengine_get();
 
         printk(KERN_INFO "async_tx: api initialized (async)\n");
 
@@ -150,7 +39,7 @@ static int __init async_tx_init(void)
 
 static void __exit async_tx_exit(void)
 {
-        dma_async_client_unregister(&async_tx_dma);
+        dmaengine_put();
 }
 
 /**
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 90aca505a1df..3f1849b7f5ef 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -600,10 +600,9 @@ static void dma_clients_notify_available(void)
 }
 
 /**
- * dma_async_client_register - register a &dma_client
- * @client: ptr to a client structure with valid 'event_callback' and 'cap_mask'
+ * dmaengine_get - register interest in dma_channels
  */
-void dma_async_client_register(struct dma_client *client)
+void dmaengine_get(void)
 {
         struct dma_device *device, *_d;
         struct dma_chan *chan;
@@ -634,25 +633,18 @@ void dma_async_client_register(struct dma_client *client)
          */
         if (dmaengine_ref_count == 1)
                 dma_channel_rebalance();
-        list_add_tail(&client->global_node, &dma_client_list);
         mutex_unlock(&dma_list_mutex);
 }
-EXPORT_SYMBOL(dma_async_client_register);
+EXPORT_SYMBOL(dmaengine_get);
 
 /**
- * dma_async_client_unregister - unregister a client and free the &dma_client
- * @client: &dma_client to free
- *
- * Force frees any allocated DMA channels, frees the &dma_client memory
+ * dmaengine_put - let dma drivers be removed when ref_count == 0
  */
-void dma_async_client_unregister(struct dma_client *client)
+void dmaengine_put(void)
 {
         struct dma_device *device;
         struct dma_chan *chan;
 
-        if (!client)
-                return;
-
         mutex_lock(&dma_list_mutex);
         dmaengine_ref_count--;
         BUG_ON(dmaengine_ref_count < 0);
@@ -663,11 +655,9 @@ void dma_async_client_unregister(struct dma_client *client)
                 list_for_each_entry(chan, &device->channels, device_node)
                         dma_chan_put(chan);
         }
-
-        list_del(&client->global_node);
         mutex_unlock(&dma_list_mutex);
 }
-EXPORT_SYMBOL(dma_async_client_unregister);
+EXPORT_SYMBOL(dmaengine_put);
 
 /**
  * dma_async_client_chan_request - send all available channels to the
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index d63544cf8a1a..37d95db156d3 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -318,8 +318,8 @@ struct dma_device {
 
 /* --- public DMA engine API --- */
 
-void dma_async_client_register(struct dma_client *client);
-void dma_async_client_unregister(struct dma_client *client);
+void dmaengine_get(void);
+void dmaengine_put(void);
 void dma_async_client_chan_request(struct dma_client *client);
 dma_cookie_t dma_async_memcpy_buf_to_buf(struct dma_chan *chan,
         void *dest, void *src, size_t len);
diff --git a/net/core/dev.c b/net/core/dev.c
index bbb07dbe1740..7596fc9403c8 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4894,8 +4894,7 @@ static int __init netdev_dma_register(void)
         }
         spin_lock_init(&net_dma.lock);
         dma_cap_set(DMA_MEMCPY, net_dma.client.cap_mask);
-        dma_async_client_register(&net_dma.client);
-        dma_async_client_chan_request(&net_dma.client);
+        dmaengine_get();
         return 0;
 }