Revert "dmaengine: mv_xor: bug fix for racing condition in descriptor…

…s cleanup"

This reverts commit 42f77f1.

drivers/dma/mv_xor.c

@@ -393,8 +393,7 @@ static void __mv_xor_slot_cleanup(struct mv_xor_chan *mv_chan)
 	dma_cookie_t cookie = 0;
 	int busy = mv_chan_is_busy(mv_chan);
 	u32 current_desc = mv_chan_get_current_desc(mv_chan);
-	int current_cleaned = 0;
-	struct mv_xor_desc *hw_desc;
+	int seen_current = 0;
 
 	dev_dbg(mv_chan_to_devp(mv_chan), "%s %d\n", __func__, __LINE__);
 	dev_dbg(mv_chan_to_devp(mv_chan), "current_desc %x\n", current_desc);
@@ -406,57 +405,38 @@ static void __mv_xor_slot_cleanup(struct mv_xor_chan *mv_chan)
 
 	list_for_each_entry_safe(iter, _iter, &mv_chan->chain,
 					chain_node) {
+		prefetch(_iter);
+		prefetch(&_iter->async_tx);
 
-		/* clean finished descriptors */
-		hw_desc = iter->hw_desc;
-		if (hw_desc->status & XOR_DESC_SUCCESS) {
-			cookie = mv_xor_run_tx_complete_actions(iter, mv_chan,
-								cookie);
-
-			/* done processing desc, clean slot */
-			mv_xor_clean_slot(iter, mv_chan);
+		/* do not advance past the current descriptor loaded into the
+		 * hardware channel, subsequent descriptors are either in
+		 * process or have not been submitted
+		 */
+		if (seen_current)
+			break;
 
-			/* break if we did cleaned the current */
-			if (iter->async_tx.phys == current_desc) {
-				current_cleaned = 1;
-				break;
-			}
-		} else {
-			if (iter->async_tx.phys == current_desc) {
-				current_cleaned = 0;
+		/* stop the search if we reach the current descriptor and the
+		 * channel is busy
+		 */
+		if (iter->async_tx.phys == current_desc) {
+			seen_current = 1;
+			if (busy)
 				break;
-			}
 		}
+
+		cookie = mv_xor_run_tx_complete_actions(iter, mv_chan, cookie);
+
+		if (mv_xor_clean_slot(iter, mv_chan))
+			break;
 	}
 
 	if ((busy == 0) && !list_empty(&mv_chan->chain)) {
-		if (current_cleaned) {
-			/*
-			 * current descriptor cleaned and removed, run
-			 * from list head
-			 */
-			iter = list_entry(mv_chan->chain.next,
-					  struct mv_xor_desc_slot,
-					  chain_node);
-			mv_xor_start_new_chain(mv_chan, iter);
-		} else {
-			if (!list_is_last(&iter->chain_node, &mv_chan->chain)) {
-				/*
-				 * descriptors are still waiting after
-				 * current, trigger them
-				 */
-				iter = list_entry(iter->chain_node.next,
-						  struct mv_xor_desc_slot,
-						  chain_node);
-				mv_xor_start_new_chain(mv_chan, iter);
-			} else {
-				/*
-				 * some descriptors are still waiting
-				 * to be cleaned
-				 */
-				tasklet_schedule(&mv_chan->irq_tasklet);
-			}
-		}
+		struct mv_xor_desc_slot *chain_head;
+		chain_head = list_entry(mv_chan->chain.next,
+					struct mv_xor_desc_slot,
+					chain_node);
+
+		mv_xor_start_new_chain(mv_chan, chain_head);
 	}
 
 	if (cookie > 0)

drivers/dma/mv_xor.h

@@ -32,7 +32,6 @@
 #define XOR_OPERATION_MODE_XOR		0
 #define XOR_OPERATION_MODE_MEMCPY	2
 #define XOR_OPERATION_MODE_MEMSET	4
-#define XOR_DESC_SUCCESS		0x40000000
 
 #define XOR_CURR_DESC(chan)	(chan->mmr_base + 0x210 + (chan->idx * 4))
 #define XOR_NEXT_DESC(chan)	(chan->mmr_base + 0x200 + (chan->idx * 4))