net: ipa: add a transaction committed list

We currently put a transaction on the pending list when it has
been committed.  But until the channel's doorbell rings, these
transactions aren't actually "owned" by the hardware yet.

Add a new "committed" state (and list), to represent transactions
that have been committed but not yet sent to hardware.  Define
"pending" to mean committed transactions that have been sent
to hardware but have not yet completed.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ipa/gsi.c

@@ -720,6 +720,9 @@ static struct gsi_trans *gsi_channel_trans_last(struct gsi_channel *channel)
 	 */
 	if (channel->toward_ipa) {
 		list = &trans_info->alloc;
+		if (!list_empty(list))
+			goto done;
+		list = &trans_info->committed;
 		if (!list_empty(list))
 			goto done;
 		list = &trans_info->pending;
@@ -1364,7 +1367,7 @@ gsi_event_trans(struct gsi *gsi, struct gsi_event *event)
  * first *unfilled* event in the ring (following the last filled one).
  *
  * Events are sequential within the event ring, and transactions are
- * sequential within the transaction pool.
+ * sequential within the transaction array.
  *
  * Note that @index always refers to an element *within* the event ring.
  */

drivers/net/ipa/gsi.h

@@ -89,7 +89,8 @@ struct gsi_trans_info {
 
 	spinlock_t spinlock;		/* protects updates to the lists */
 	struct list_head alloc;		/* allocated, not committed */
-	struct list_head pending;	/* committed, awaiting completion */
+	struct list_head committed;	/* committed, awaiting doorbell */
+	struct list_head pending;	/* pending, awaiting completion */
 	struct list_head complete;	/* completed, awaiting poll */
 	struct list_head polled;	/* returned by gsi_channel_poll_one() */
 };
@@ -185,7 +186,7 @@ void gsi_teardown(struct gsi *gsi);
  * @gsi:	GSI pointer
  * @channel_id:	Channel whose limit is to be returned
  *
- * Return:	 The maximum number of TREs oustanding on the channel
+ * Return:	 The maximum number of TREs outstanding on the channel
  */
 u32 gsi_channel_tre_max(struct gsi *gsi, u32 channel_id);
 

drivers/net/ipa/gsi_trans.c

@@ -241,15 +241,31 @@ struct gsi_trans *gsi_channel_trans_complete(struct gsi_channel *channel)
 					struct gsi_trans, links);
 }
 
-/* Move a transaction from the allocated list to the pending list */
+/* Move a transaction from the allocated list to the committed list */
+static void gsi_trans_move_committed(struct gsi_trans *trans)
+{
+	struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
+	struct gsi_trans_info *trans_info = &channel->trans_info;
+
+	spin_lock_bh(&trans_info->spinlock);
+
+	list_move_tail(&trans->links, &trans_info->committed);
+
+	spin_unlock_bh(&trans_info->spinlock);
+}
+
+/* Move transactions from the committed list to the pending list */
 static void gsi_trans_move_pending(struct gsi_trans *trans)
 {
 	struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
 	struct gsi_trans_info *trans_info = &channel->trans_info;
+	struct list_head list;
 
 	spin_lock_bh(&trans_info->spinlock);
 
-	list_move_tail(&trans->links, &trans_info->pending);
+	/* Move this transaction and all predecessors to the pending list */
+	list_cut_position(&list, &trans_info->committed, &trans->links);
+	list_splice_tail(&list, &trans_info->pending);
 
 	spin_unlock_bh(&trans_info->spinlock);
 }
@@ -581,13 +597,14 @@ static void __gsi_trans_commit(struct gsi_trans *trans, bool ring_db)
 	if (channel->toward_ipa)
 		gsi_trans_tx_committed(trans);
 
-	gsi_trans_move_pending(trans);
+	gsi_trans_move_committed(trans);
 
 	/* Ring doorbell if requested, or if all TREs are allocated */
 	if (ring_db || !atomic_read(&channel->trans_info.tre_avail)) {
 		/* Report what we're handing off to hardware for TX channels */
 		if (channel->toward_ipa)
 			gsi_trans_tx_queued(trans);
+		gsi_trans_move_pending(trans);
 		gsi_channel_doorbell(channel);
 	}
 }
@@ -710,7 +727,7 @@ int gsi_channel_trans_init(struct gsi *gsi, u32 channel_id)
 		return -ENOMEM;
 
 	/* We can't use more TREs than there are available in the ring.
-	 * This limits the number of transactions that can be oustanding.
+	 * This limits the number of transactions that can be outstanding.
 	 * Worst case is one TRE per transaction (but we actually limit
 	 * it to something a little less than that).  We allocate resources
 	 * for transactions (including transaction structures) based on
@@ -747,6 +764,7 @@ int gsi_channel_trans_init(struct gsi *gsi, u32 channel_id)
 
 	spin_lock_init(&trans_info->spinlock);
 	INIT_LIST_HEAD(&trans_info->alloc);
+	INIT_LIST_HEAD(&trans_info->committed);
 	INIT_LIST_HEAD(&trans_info->pending);
 	INIT_LIST_HEAD(&trans_info->complete);
 	INIT_LIST_HEAD(&trans_info->polled);