async_tx: trim dma_async_tx_descriptor in 'no channel switch' case

Saves 24 bytes per descriptor (64-bit) when the channel-switching
capabilities of async_tx are not required.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/crypto/async_tx/async_tx.c b/crypto/async_tx/async_tx.c
index f9cdf04..7f2c00a 100644 (file)
--- a/crypto/async_tx/async_tx.c
+++ b/crypto/async_tx/async_tx.c
@@ -81,18 +81,13 @@ async_tx_channel_switch(struct dma_async_tx_descriptor *depend_tx,
        struct dma_device *device = chan->device;
        struct dma_async_tx_descriptor *intr_tx = (void *) ~0;
 
-       #ifdef CONFIG_ASYNC_TX_DISABLE_CHANNEL_SWITCH
-       BUG();
-       #endif
-
        /* first check to see if we can still append to depend_tx */
-       spin_lock_bh(&depend_tx->lock);
-       if (depend_tx->parent && depend_tx->chan == tx->chan) {
-               tx->parent = depend_tx;
-               depend_tx->next = tx;
+       txd_lock(depend_tx);
+       if (txd_parent(depend_tx) && depend_tx->chan == tx->chan) {
+               txd_chain(depend_tx, tx);
                intr_tx = NULL;
        }
-       spin_unlock_bh(&depend_tx->lock);
+       txd_unlock(depend_tx);
 
        /* attached dependency, flush the parent channel */
        if (!intr_tx) {
@@ -111,24 +106,22 @@ async_tx_channel_switch(struct dma_async_tx_descriptor *depend_tx,
        if (intr_tx) {
                intr_tx->callback = NULL;
                intr_tx->callback_param = NULL;
-               tx->parent = intr_tx;
-               /* safe to set ->next outside the lock since we know we are
+               /* safe to chain outside the lock since we know we are
                 * not submitted yet
                 */
-               intr_tx->next = tx;
+               txd_chain(intr_tx, tx);
 
                /* check if we need to append */
-               spin_lock_bh(&depend_tx->lock);
-               if (depend_tx->parent) {
-                       intr_tx->parent = depend_tx;
-                       depend_tx->next = intr_tx;
+               txd_lock(depend_tx);
+               if (txd_parent(depend_tx)) {
+                       txd_chain(depend_tx, intr_tx);
                        async_tx_ack(intr_tx);
                        intr_tx = NULL;
                }
-               spin_unlock_bh(&depend_tx->lock);
+               txd_unlock(depend_tx);
 
                if (intr_tx) {
-                       intr_tx->parent = NULL;
+                       txd_clear_parent(intr_tx);
                        intr_tx->tx_submit(intr_tx);
                        async_tx_ack(intr_tx);
                }
@@ -176,21 +169,20 @@ async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
                 * 2/ dependencies are 1:1 i.e. two transactions can
                 * not depend on the same parent
                 */
-               BUG_ON(async_tx_test_ack(depend_tx) || depend_tx->next ||
-                      tx->parent);
+               BUG_ON(async_tx_test_ack(depend_tx) || txd_next(depend_tx) ||
+                      txd_parent(tx));
 
                /* the lock prevents async_tx_run_dependencies from missing
                 * the setting of ->next when ->parent != NULL
                 */
-               spin_lock_bh(&depend_tx->lock);
-               if (depend_tx->parent) {
+               txd_lock(depend_tx);
+               if (txd_parent(depend_tx)) {
                        /* we have a parent so we can not submit directly
                         * if we are staying on the same channel: append
                         * else: channel switch
                         */
                        if (depend_tx->chan == chan) {
-                               tx->parent = depend_tx;
-                               depend_tx->next = tx;
+                               txd_chain(depend_tx, tx);
                                s = ASYNC_TX_SUBMITTED;
                        } else
                                s = ASYNC_TX_CHANNEL_SWITCH;
@@ -203,7 +195,7 @@ async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
                        else
                                s = ASYNC_TX_CHANNEL_SWITCH;
                }
-               spin_unlock_bh(&depend_tx->lock);
+               txd_unlock(depend_tx);
 
                switch (s) {
                case ASYNC_TX_SUBMITTED:
@@ -212,12 +204,12 @@ async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
                        async_tx_channel_switch(depend_tx, tx);
                        break;
                case ASYNC_TX_DIRECT_SUBMIT:
-                       tx->parent = NULL;
+                       txd_clear_parent(tx);
                        tx->tx_submit(tx);
                        break;
                }
        } else {
-               tx->parent = NULL;
+               txd_clear_parent(tx);
                tx->tx_submit(tx);
        }
 

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index d18b5d0..fcfe1a6 100644 (file)
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -978,7 +978,9 @@ void dma_async_tx_descriptor_init(struct dma_async_tx_descriptor *tx,
        struct dma_chan *chan)
 {
        tx->chan = chan;
+       #ifndef CONFIG_ASYNC_TX_DISABLE_CHANNEL_SWITCH
        spin_lock_init(&tx->lock);
+       #endif
 }
 EXPORT_SYMBOL(dma_async_tx_descriptor_init);
 
@@ -1011,7 +1013,7 @@ EXPORT_SYMBOL_GPL(dma_wait_for_async_tx);
  */
 void dma_run_dependencies(struct dma_async_tx_descriptor *tx)
 {
-       struct dma_async_tx_descriptor *dep = tx->next;
+       struct dma_async_tx_descriptor *dep = txd_next(tx);
        struct dma_async_tx_descriptor *dep_next;
        struct dma_chan *chan;
 
@@ -1019,7 +1021,7 @@ void dma_run_dependencies(struct dma_async_tx_descriptor *tx)
                return;
 
        /* we'll submit tx->next now, so clear the link */
-       tx->next = NULL;
+       txd_clear_next(tx);
        chan = dep->chan;
 
        /* keep submitting up until a channel switch is detected
@@ -1027,14 +1029,14 @@ void dma_run_dependencies(struct dma_async_tx_descriptor *tx)
         * processing the interrupt from async_tx_channel_switch
         */
        for (; dep; dep = dep_next) {
-               spin_lock_bh(&dep->lock);
-               dep->parent = NULL;
-               dep_next = dep->next;
+               txd_lock(dep);
+               txd_clear_parent(dep);
+               dep_next = txd_next(dep);
                if (dep_next && dep_next->chan == chan)
-                       dep->next = NULL; /* ->next will be submitted */
+                       txd_clear_next(dep); /* ->next will be submitted */
                else
                        dep_next = NULL; /* submit current dep and terminate */
-               spin_unlock_bh(&dep->lock);
+               txd_unlock(dep);
 
                dep->tx_submit(dep);
        }

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 20ea12c..cb23497 100644 (file)
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -230,11 +230,71 @@ struct dma_async_tx_descriptor {
        dma_cookie_t (*tx_submit)(struct dma_async_tx_descriptor *tx);
        dma_async_tx_callback callback;
        void *callback_param;
+#ifndef CONFIG_ASYNC_TX_DISABLE_CHANNEL_SWITCH
        struct dma_async_tx_descriptor *next;
        struct dma_async_tx_descriptor *parent;
        spinlock_t lock;
+#endif
 };
 
+#ifdef CONFIG_ASYNC_TX_DISABLE_CHANNEL_SWITCH
+static inline void txd_lock(struct dma_async_tx_descriptor *txd)
+{
+}
+static inline void txd_unlock(struct dma_async_tx_descriptor *txd)
+{
+}
+static inline void txd_chain(struct dma_async_tx_descriptor *txd, struct dma_async_tx_descriptor *next)
+{
+       BUG();
+}
+static inline void txd_clear_parent(struct dma_async_tx_descriptor *txd)
+{
+}
+static inline void txd_clear_next(struct dma_async_tx_descriptor *txd)
+{
+}
+static inline struct dma_async_tx_descriptor *txd_next(struct dma_async_tx_descriptor *txd)
+{
+       return NULL;
+}
+static inline struct dma_async_tx_descriptor *txd_parent(struct dma_async_tx_descriptor *txd)
+{
+       return NULL;
+}
+
+#else
+static inline void txd_lock(struct dma_async_tx_descriptor *txd)
+{
+       spin_lock_bh(&txd->lock);
+}
+static inline void txd_unlock(struct dma_async_tx_descriptor *txd)
+{
+       spin_unlock_bh(&txd->lock);
+}
+static inline void txd_chain(struct dma_async_tx_descriptor *txd, struct dma_async_tx_descriptor *next)
+{
+       txd->next = next;
+       next->parent = txd;
+}
+static inline void txd_clear_parent(struct dma_async_tx_descriptor *txd)
+{
+       txd->parent = NULL;
+}
+static inline void txd_clear_next(struct dma_async_tx_descriptor *txd)
+{
+       txd->next = NULL;
+}
+static inline struct dma_async_tx_descriptor *txd_parent(struct dma_async_tx_descriptor *txd)
+{
+       return txd->parent;
+}
+static inline struct dma_async_tx_descriptor *txd_next(struct dma_async_tx_descriptor *txd)
+{
+       return txd->next;
+}
+#endif
+
 /**
  * struct dma_device - info on the entity supplying DMA services
  * @chancnt: how many DMA channels are supported