Commit ca738f5a authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Jakub Kicinski
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s390/ctcm: Avoid temporary allocation of struct pdu. 



The size of struct pdu is 8 byte. The memory 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 pdu and use the resulting skb pointer
instead.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
[jwi: Fix-up the pdu_offset, adjust skb->len for the pushed length.
      Reflow the commit msg.]
Signed-off-by: default avatarJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent d38aa396

drivers/s390/net/ctcm_main.c

+8 −25
Original line number Diff line number Diff line
@@ -665,24 +665,16 @@ static int ctcmpc_transmit_skb(struct channel *ch, struct sk_buff *skb) 
	if ((fsm_getstate(ch->fsm) != CTC_STATE_TXIDLE) || grp->in_sweep) {

		spin_lock_irqsave(&ch->collect_lock, saveflags);

		refcount_inc(&skb->users);

		p_header = kmalloc(PDU_HEADER_LENGTH, gfp_type());



		if (!p_header) {

			spin_unlock_irqrestore(&ch->collect_lock, saveflags);

				goto nomem_exit;

		}



		p_header->pdu_offset = skb->len;

		p_header = skb_push(skb, PDU_HEADER_LENGTH);

		p_header->pdu_offset = skb->len - PDU_HEADER_LENGTH;

		p_header->pdu_proto = 0x01;

		p_header->pdu_flag = 0x00;

		if (be16_to_cpu(skb->protocol) == ETH_P_SNAP) {

			p_header->pdu_flag |= PDU_FIRST | PDU_CNTL;

			p_header->pdu_flag = PDU_FIRST | PDU_CNTL;

		} else {

			p_header->pdu_flag |= PDU_FIRST;

			p_header->pdu_flag = PDU_FIRST;

		}

		p_header->pdu_seq = 0;

		memcpy(skb_push(skb, PDU_HEADER_LENGTH), p_header,

		       PDU_HEADER_LENGTH);



		CTCM_PR_DEBUG("%s(%s): Put on collect_q - skb len: %04x \n"

				"pdu header and data for up to 32 bytes:\n",
@@ -691,7 +683,6 @@ static int ctcmpc_transmit_skb(struct channel *ch, struct sk_buff *skb) 


		skb_queue_tail(&ch->collect_queue, skb);

		ch->collect_len += skb->len;

		kfree(p_header);



		spin_unlock_irqrestore(&ch->collect_lock, saveflags);

			goto done;
@@ -721,23 +712,15 @@ static int ctcmpc_transmit_skb(struct channel *ch, struct sk_buff *skb) 
		}

	}



	p_header = kmalloc(PDU_HEADER_LENGTH, gfp_type());



	if (!p_header)

		goto nomem_exit;



	p_header->pdu_offset = skb->len;

	p_header = skb_push(skb, PDU_HEADER_LENGTH);

	p_header->pdu_offset = skb->len - PDU_HEADER_LENGTH;

	p_header->pdu_proto = 0x01;

	p_header->pdu_flag = 0x00;

	p_header->pdu_seq = 0;

	if (be16_to_cpu(skb->protocol) == ETH_P_SNAP) {

		p_header->pdu_flag |= PDU_FIRST | PDU_CNTL;

		p_header->pdu_flag = PDU_FIRST | PDU_CNTL;

	} else {

		p_header->pdu_flag |= PDU_FIRST;

		p_header->pdu_flag = PDU_FIRST;

	}

	memcpy(skb_push(skb, PDU_HEADER_LENGTH), p_header, PDU_HEADER_LENGTH);



	kfree(p_header);



	if (ch->collect_len > 0) {

		spin_lock_irqsave(&ch->collect_lock, saveflags);

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