Commit df41c19a authored by Xie He's avatar Xie He Committed by Jakub Kicinski
Browse files

drivers/net/wan/hdlc_fr: Move the skb_headroom check out of fr_hard_header 



Move the skb_headroom check out of fr_hard_header and into pvc_xmit.
This has two benefits:

1. Originally we only do this check for skbs sent by users on Ethernet-
emulating PVC devices. After the change we do this check for skbs sent on
normal PVC devices, too.
(Also add a comment to make it clear that this is only a protection
against upper layers that don't take dev->needed_headroom into account.
Such upper layers should be rare and I believe they should be fixed.)

2. After the change we can simplify the parameter list of fr_hard_header.
We no longer need to use a pointer to pointers (skb_p) because we no
longer need to replace the skb inside fr_hard_header.

Cc: Krzysztof Halasa <khc@pm.waw.pl>
Signed-off-by: default avatarXie He <xie.he.0141@gmail.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent e0b2e0d8

drivers/net/wan/hdlc_fr.c

+17 −13
Original line number Diff line number Diff line
@@ -271,10 +271,8 @@ static inline struct net_device **get_dev_p(struct pvc_device *pvc, 
}





static int fr_hard_header(struct sk_buff **skb_p, u16 dlci)

static int fr_hard_header(struct sk_buff *skb, u16 dlci)

{

	struct sk_buff *skb = *skb_p;



	if (!skb->dev) { /* Control packets */

		switch (dlci) {

		case LMI_CCITT_ANSI_DLCI:
@@ -316,13 +314,6 @@ static int fr_hard_header(struct sk_buff **skb_p, u16 dlci) 
		}



	} else if (skb->dev->type == ARPHRD_ETHER) {

		if (skb_headroom(skb) < 10) {

			struct sk_buff *skb2 = skb_realloc_headroom(skb, 10);

			if (!skb2)

				return -ENOBUFS;

			dev_kfree_skb(skb);

			skb = *skb_p = skb2;

		}

		skb_push(skb, 10);

		skb->data[3] = FR_PAD;

		skb->data[4] = NLPID_SNAP;
@@ -429,8 +420,21 @@ static netdev_tx_t pvc_xmit(struct sk_buff *skb, struct net_device *dev) 
		}

	}



	/* We already requested the header space with dev->needed_headroom.

	 * So this is just a protection in case the upper layer didn't take

	 * dev->needed_headroom into consideration.

	 */

	if (skb_headroom(skb) < 10) {

		struct sk_buff *skb2 = skb_realloc_headroom(skb, 10);



		if (!skb2)

			goto drop;

		dev_kfree_skb(skb);

		skb = skb2;

	}



	skb->dev = dev;

	if (fr_hard_header(&skb, pvc->dlci))

	if (fr_hard_header(skb, pvc->dlci))

		goto drop;



	dev->stats.tx_bytes += skb->len;
@@ -498,9 +502,9 @@ static void fr_lmi_send(struct net_device *dev, int fullrep) 
	memset(skb->data, 0, len);

	skb_reserve(skb, 4);

	if (lmi == LMI_CISCO) {

		fr_hard_header(&skb, LMI_CISCO_DLCI);

		fr_hard_header(skb, LMI_CISCO_DLCI);

	} else {

		fr_hard_header(&skb, LMI_CCITT_ANSI_DLCI);

		fr_hard_header(skb, LMI_CCITT_ANSI_DLCI);

	}

	data = skb_tail_pointer(skb);

	data[i++] = LMI_CALLREF;

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