dmaengine: make clients responsible for managing channels
[linux-2.6.git] / net / core / dev.c
index ee051bb..835202f 100644 (file)
@@ -151,9 +151,22 @@ static struct list_head ptype_base[16] __read_mostly;      /* 16 way hashed list */
 static struct list_head ptype_all __read_mostly;       /* Taps */
 
 #ifdef CONFIG_NET_DMA
-static struct dma_client *net_dma_client;
-static unsigned int net_dma_count;
-static spinlock_t net_dma_event_lock;
+struct net_dma {
+       struct dma_client client;
+       spinlock_t lock;
+       cpumask_t channel_mask;
+       struct dma_chan *channels[NR_CPUS];
+};
+
+static enum dma_state_client
+netdev_dma_event(struct dma_client *client, struct dma_chan *chan,
+       enum dma_state state);
+
+static struct net_dma net_dma = {
+       .client = {
+               .event_callback = netdev_dma_event,
+       },
+};
 #endif
 
 /*
@@ -2015,12 +2028,13 @@ out:
         * There may not be any more sk_buffs coming right now, so push
         * any pending DMA copies to hardware
         */
-       if (net_dma_client) {
-               struct dma_chan *chan;
-               rcu_read_lock();
-               list_for_each_entry_rcu(chan, &net_dma_client->channels, client_node)
-                       dma_async_memcpy_issue_pending(chan);
-               rcu_read_unlock();
+       if (!cpus_empty(net_dma.channel_mask)) {
+               int chan_idx;
+               for_each_cpu_mask(chan_idx, net_dma.channel_mask) {
+                       struct dma_chan *chan = net_dma.channels[chan_idx];
+                       if (chan)
+                               dma_async_memcpy_issue_pending(chan);
+               }
        }
 #endif
        return;
@@ -3563,12 +3577,13 @@ static int dev_cpu_callback(struct notifier_block *nfb,
  * This is called when the number of channels allocated to the net_dma_client
  * changes.  The net_dma_client tries to have one DMA channel per CPU.
  */
-static void net_dma_rebalance(void)
+
+static void net_dma_rebalance(struct net_dma *net_dma)
 {
-       unsigned int cpu, i, n;
+       unsigned int cpu, i, n, chan_idx;
        struct dma_chan *chan;
 
-       if (net_dma_count == 0) {
+       if (cpus_empty(net_dma->channel_mask)) {
                for_each_online_cpu(cpu)
                        rcu_assign_pointer(per_cpu(softnet_data, cpu).net_dma, NULL);
                return;
@@ -3577,10 +3592,12 @@ static void net_dma_rebalance(void)
        i = 0;
        cpu = first_cpu(cpu_online_map);
 
-       rcu_read_lock();
-       list_for_each_entry(chan, &net_dma_client->channels, client_node) {
-               n = ((num_online_cpus() / net_dma_count)
-                  + (i < (num_online_cpus() % net_dma_count) ? 1 : 0));
+       for_each_cpu_mask(chan_idx, net_dma->channel_mask) {
+               chan = net_dma->channels[chan_idx];
+
+               n = ((num_online_cpus() / cpus_weight(net_dma->channel_mask))
+                  + (i < (num_online_cpus() %
+                       cpus_weight(net_dma->channel_mask)) ? 1 : 0));
 
                while(n) {
                        per_cpu(softnet_data, cpu).net_dma = chan;
@@ -3589,7 +3606,6 @@ static void net_dma_rebalance(void)
                }
                i++;
        }
-       rcu_read_unlock();
 }
 
 /**
@@ -3598,23 +3614,53 @@ static void net_dma_rebalance(void)
  * @chan: DMA channel for the event
  * @event: event type
  */
-static void netdev_dma_event(struct dma_client *client, struct dma_chan *chan,
-       enum dma_event event)
-{
-       spin_lock(&net_dma_event_lock);
-       switch (event) {
-       case DMA_RESOURCE_ADDED:
-               net_dma_count++;
-               net_dma_rebalance();
+static enum dma_state_client
+netdev_dma_event(struct dma_client *client, struct dma_chan *chan,
+       enum dma_state state)
+{
+       int i, found = 0, pos = -1;
+       struct net_dma *net_dma =
+               container_of(client, struct net_dma, client);
+       enum dma_state_client ack = DMA_DUP; /* default: take no action */
+
+       spin_lock(&net_dma->lock);
+       switch (state) {
+       case DMA_RESOURCE_AVAILABLE:
+               for (i = 0; i < NR_CPUS; i++)
+                       if (net_dma->channels[i] == chan) {
+                               found = 1;
+                               break;
+                       } else if (net_dma->channels[i] == NULL && pos < 0)
+                               pos = i;
+
+               if (!found && pos >= 0) {
+                       ack = DMA_ACK;
+                       net_dma->channels[pos] = chan;
+                       cpu_set(pos, net_dma->channel_mask);
+                       net_dma_rebalance(net_dma);
+               }
                break;
        case DMA_RESOURCE_REMOVED:
-               net_dma_count--;
-               net_dma_rebalance();
+               for (i = 0; i < NR_CPUS; i++)
+                       if (net_dma->channels[i] == chan) {
+                               found = 1;
+                               pos = i;
+                               break;
+                       }
+
+               if (found) {
+                       ack = DMA_ACK;
+                       cpu_clear(pos, net_dma->channel_mask);
+                       net_dma->channels[i] = NULL;
+                       net_dma_rebalance(net_dma);
+               }
                break;
        default:
                break;
        }
-       spin_unlock(&net_dma_event_lock);
+       spin_unlock(&net_dma->lock);
+
+       return ack;
 }
 
 /**
@@ -3622,12 +3668,10 @@ static void netdev_dma_event(struct dma_client *client, struct dma_chan *chan,
  */
 static int __init netdev_dma_register(void)
 {
-       spin_lock_init(&net_dma_event_lock);
-       net_dma_client = dma_async_client_register(netdev_dma_event);
-       if (net_dma_client == NULL)
-               return -ENOMEM;
-
-       dma_async_client_chan_request(net_dma_client, num_online_cpus());
+       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);
        return 0;
 }