[PATCH v2 2/6] s390/ctcm: Avoid temporary allocation of struct qllc.

[Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>]

The size of struct qllc is 2 byte. The memory for is allocated, initialized,
used and deallocated a few lines later.

It is more efficient to avoid the allocation/free dance and assign the
values directly to skb's data part instead of using memcpy() for it.

Avoid an allocation of struct qllc and use the resulting skb pointer instead.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
 drivers/s390/net/ctcm_mpc.c | 22 +++++-----------------
 1 file changed, 5 insertions(+), 17 deletions(-)

diff --git a/drivers/s390/net/ctcm_mpc.c b/drivers/s390/net/ctcm_mpc.c
index 0929ff2fd5c1a..76a9e0d0c0710 100644
--- a/drivers/s390/net/ctcm_mpc.c
+++ b/drivers/s390/net/ctcm_mpc.c
@@ -2049,7 +2049,6 @@ static void mpc_action_rcvd_xid7(fsm_instance *fsm, int event, void *arg)
  */
 static int mpc_send_qllc_discontact(struct net_device *dev)
 {
-	__u32	new_len	= 0;
 	struct sk_buff   *skb;
 	struct qllc      *qllcptr;
 	struct ctcm_priv *priv = dev->ml_priv;
@@ -2080,31 +2079,20 @@ static int mpc_send_qllc_discontact(struct net_device *dev)
 	case MPCG_STATE_FLOWC:
 	case MPCG_STATE_READY:
 		grp->send_qllc_disc = 2;
-		new_len = sizeof(struct qllc);
-		qllcptr = kzalloc(new_len, gfp_type() | GFP_DMA);
-		if (qllcptr == NULL) {
-			CTCM_DBF_TEXT_(MPC_ERROR, CTC_DBF_ERROR,
-				"%s(%s): qllcptr allocation error",
-						CTCM_FUNTAIL, dev->name);
-			return -ENOMEM;
-		}
-
-		qllcptr->qllc_address = 0xcc;
-		qllcptr->qllc_commands = 0x03;
-
-		skb = __dev_alloc_skb(new_len, GFP_ATOMIC);
 
+		skb = __dev_alloc_skb(sizeof(struct qllc), GFP_ATOMIC);
 		if (skb == NULL) {
 			CTCM_DBF_TEXT_(MPC_ERROR, CTC_DBF_ERROR,
 				"%s(%s): skb allocation error",
 						CTCM_FUNTAIL, dev->name);
 			priv->stats.rx_dropped++;
-			kfree(qllcptr);
 			return -ENOMEM;
 		}
 
-		skb_put_data(skb, qllcptr, new_len);
-		kfree(qllcptr);
+
+		qllcptr = skb_put(skb, sizeof(struct qllc));
+		qllcptr->qllc_address = 0xcc;
+		qllcptr->qllc_commands = 0x03;
 
 		if (skb_headroom(skb) < 4) {
 			CTCM_DBF_TEXT_(MPC_ERROR, CTC_DBF_ERROR,
-- 
2.29.2