s390/ctcm: Avoid temporary allocation of struct qllc.

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@linutronix.de>
[jwi: remove a newline, reflow the commit msg]
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/s390/net/ctcm_mpc.c b/drivers/s390/net/ctcm_mpc.c
index 293d8870968c100d5e66144c6ddf147d55d4554e..8ae49732d1d2092f01be27e06416efe671f435f6 100644 (file)
--- a/drivers/s390/net/ctcm_mpc.c
+++ b/drivers/s390/net/ctcm_mpc.c
@@ -2048,7 +2048,6 @@ 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;
@@ -2079,31 +2078,19 @@ 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,