From deee1de4bf847a34405c58f184076a5f5af66a4d Mon Sep 17 00:00:00 2001
From: Andrew Rybchenko <arybchik@FreeBSD.org>
Date: Sat, 16 May 2015 05:37:47 +0000
Subject: [PATCH] sfxge: get rid of locked variable in sfxge_tx_packet_add()

Now each branch has one and only one possible TxQ lock state.
It simplifies understanding of the code.

Reviewed by:    gnn
Sponsored by:   Solarflare Communications, Inc.
MFC after:      2 days
Differential Revision: https://reviews.freebsd.org/D2551
---
 sys/dev/sfxge/sfxge_tx.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/sys/dev/sfxge/sfxge_tx.c b/sys/dev/sfxge/sfxge_tx.c
index 1652d4c539b..0ac7dad2d10 100644
--- a/sys/dev/sfxge/sfxge_tx.c
+++ b/sys/dev/sfxge/sfxge_tx.c
@@ -602,7 +602,6 @@ sfxge_tx_qdpl_put_unlocked(struct sfxge_txq *txq, struct mbuf *mbuf)
 int
 sfxge_tx_packet_add(struct sfxge_txq *txq, struct mbuf *m)
 {
-	int locked;
 	int rc;
 
 	if (!SFXGE_LINK_UP(txq->sc)) {
@@ -616,9 +615,7 @@ sfxge_tx_packet_add(struct sfxge_txq *txq, struct mbuf *m)
 	 * the packet will be appended to the "get list" of the deferred
 	 * packet list.  Otherwise, it will be pushed on the "put list".
 	 */
-	locked = SFXGE_TXQ_TRYLOCK(txq);
-
-	if (locked) {
+	if (SFXGE_TXQ_TRYLOCK(txq)) {
 		/* First swizzle put-list to get-list to keep order */
 		sfxge_tx_qdpl_swizzle(txq);
 
@@ -627,6 +624,10 @@ sfxge_tx_packet_add(struct sfxge_txq *txq, struct mbuf *m)
 			SFXGE_TXQ_UNLOCK(txq);
 			goto fail;
 		}
+
+		/* Try to service the list. */
+		sfxge_tx_qdpl_service(txq);
+		/* Lock has been dropped. */
 	} else {
 		rc = sfxge_tx_qdpl_put_unlocked(txq, m);
 		if (rc != 0)
@@ -639,14 +640,13 @@ sfxge_tx_packet_add(struct sfxge_txq *txq, struct mbuf *m)
 		 * the deferred packet list.  If we are not able to get
 		 * the lock, another thread is processing the list.
 		 */
-		locked = SFXGE_TXQ_TRYLOCK(txq);
+		if (SFXGE_TXQ_TRYLOCK(txq)) {
+			sfxge_tx_qdpl_service(txq);
+			/* Lock has been dropped. */
+		}
 	}
 
-	if (locked) {
-		/* Try to service the list. */
-		sfxge_tx_qdpl_service(txq);
-		/* Lock has been dropped. */
-	}
+	SFXGE_TXQ_LOCK_ASSERT_NOTOWNED(txq);
 
 	return (0);