net: ipa: track polled transactions with an ID

Add a transaction ID to track the first element in the transaction
array that has been polled.  Advance the ID when we are releasing a
transaction.

Temporarily add warnings that verify that the first polled
transaction tracked by the ID matches the first element on the
polled list, both when polling and freeing.

Remove the temporary warnings added by the previous commit.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ipa/gsi.h

@@ -88,6 +88,7 @@ struct gsi_trans_info {
 	u16 committed_id;		/* first committed transaction */
 	u16 pending_id;			/* first pending transaction */
 	u16 completed_id;		/* first completed transaction */
+	u16 polled_id;			/* first polled transaction */
 	struct gsi_trans *trans;	/* transaction array */
 	struct gsi_trans **map;		/* TRE -> transaction map */
 

drivers/net/ipa/gsi_trans.c

@@ -296,19 +296,12 @@ void gsi_trans_move_complete(struct gsi_trans *trans)
 	list_cut_position(&list, &trans_info->pending, &trans->links);
 	list_splice_tail(&list, &trans_info->complete);
 
-	trans = list_first_entry(&trans_info->complete,
-				 struct gsi_trans, links);
-
 	spin_unlock_bh(&trans_info->spinlock);
 
 	/* These pending transactions are now completed */
 	delta = trans_index - trans_info->pending_id + 1;
 	delta %= channel->tre_count;
 	trans_info->pending_id += delta;
-
-	WARN_ON(trans_info->completed_id == trans_info->pending_id);
-	trans_index = trans_info->completed_id % channel->tre_count;
-	WARN_ON(trans != &trans_info->trans[trans_index]);
 }
 
 /* Move a transaction from the completed list to the polled list */
@@ -322,21 +315,17 @@ void gsi_trans_move_polled(struct gsi_trans *trans)
 
 	list_move_tail(&trans->links, &trans_info->polled);
 
-	trans = list_first_entry_or_null(&trans_info->complete,
-					 struct gsi_trans, links);
+	trans = list_first_entry(&trans_info->polled,
+				 struct gsi_trans, links);
 
 	spin_unlock_bh(&trans_info->spinlock);
 
 	/* This completed transaction is now polled */
 	trans_info->completed_id++;
 
-	if (trans) {
-		trans_index = trans_info->completed_id % channel->tre_count;
-		WARN_ON(trans != &trans_info->trans[trans_index]);
-	} else {
-		WARN_ON(trans_info->completed_id !=
-			trans_info->pending_id);
-	}
+	WARN_ON(trans_info->polled_id == trans_info->completed_id);
+	trans_index = trans_info->polled_id % channel->tre_count;
+	WARN_ON(trans != &trans_info->trans[trans_index]);
 }
 
 /* Reserve some number of TREs on a channel.  Returns true if successful */
@@ -424,8 +413,11 @@ struct gsi_trans *gsi_channel_trans_alloc(struct gsi *gsi, u32 channel_id,
 /* Free a previously-allocated transaction */
 void gsi_trans_free(struct gsi_trans *trans)
 {
+	struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
 	refcount_t *refcount = &trans->refcount;
 	struct gsi_trans_info *trans_info;
+	struct gsi_trans *polled;
+	u16 trans_index;
 	bool last;
 
 	/* We must hold the lock to release the last reference */
@@ -441,6 +433,9 @@ void gsi_trans_free(struct gsi_trans *trans)
 	if (last)
 		list_del(&trans->links);
 
+	polled = list_first_entry_or_null(&trans_info->polled,
+					  struct gsi_trans, links);
+
 	spin_unlock_bh(&trans_info->spinlock);
 
 	if (!last)
@@ -458,6 +453,17 @@ void gsi_trans_free(struct gsi_trans *trans)
 		ipa_gsi_trans_release(trans);
 	}
 
+	/* This transaction is now free */
+	trans_info->polled_id++;
+
+	if (polled) {
+		trans_index = trans_info->polled_id % channel->tre_count;
+		WARN_ON(polled != &trans_info->trans[trans_index]);
+	} else {
+		WARN_ON(trans_info->polled_id !=
+			trans_info->completed_id);
+	}
+
 	/* Releasing the reserved TREs implicitly frees the sgl[] and
 	 * (if present) info[] arrays, plus the transaction itself.
 	 */
@@ -796,6 +802,7 @@ int gsi_channel_trans_init(struct gsi *gsi, u32 channel_id)
 	trans_info->committed_id = 0;
 	trans_info->pending_id = 0;
 	trans_info->completed_id = 0;
+	trans_info->polled_id = 0;
 
 	/* A completion event contains a pointer to the TRE that caused
 	 * the event (which will be the last one used by the transaction).