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

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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: Xie He <xie.he.0141@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Xie He 2020-10-07 11:32:03 -07:00 committed by Jakub Kicinski
parent e0b2e0d8e6
commit df41c19abb
1 changed files with 17 additions and 13 deletions
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30
drivers/net/wan/hdlc_fr.c
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@ -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;