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net: dsa: factor skb freeing on xmit
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As of a86d8be ("net: dsa: Factor bottom tag receive functions"),
the rcv caller frees the original SKB in case or error.

Be symmetric with that and make the xmit caller do the same.

At the same time, fix the checkpatch NULL comparison check:

        CHECK: Comparison to NULL could be written "!nskb"
    torvalds#208: FILE: net/dsa/tag_trailer.c:35:
    +	if (nskb == NULL)

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
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@vivien
vivien authored and 0day robot committed Jun 1, 2017
1 parent 24b8932 commit c094447
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Showing 9 changed files with 16 additions and 39 deletions.
8 changes: 6 additions & 2 deletions net/dsa/slave.c
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Original file line number Diff line number Diff line change
Expand Up @@ -357,10 +357,14 @@ static netdev_tx_t dsa_slave_xmit(struct sk_buff *skb, struct net_device *dev)
dev->stats.tx_packets++;
dev->stats.tx_bytes += skb->len;

/* Transmit function may have to reallocate the original SKB */
/* Transmit function may have to reallocate the original SKB,
* in which case it must have freed it. Only free it here on error.
*/
nskb = p->xmit(skb, dev);
if (!nskb)
if (!nskb) {
kfree_skb(skb);
return NETDEV_TX_OK;
}

/* SKB for netpoll still need to be mangled with the protocol-specific
* tag to be successfully transmitted
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6 changes: 1 addition & 5 deletions net/dsa/tag_brcm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,7 @@ static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb, struct net_device *dev
u8 *brcm_tag;

if (skb_cow_head(skb, BRCM_TAG_LEN) < 0)
goto out_free;
return NULL;

skb_push(skb, BRCM_TAG_LEN);

Expand All @@ -86,10 +86,6 @@ static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb, struct net_device *dev
brcm_tag[3] = (1 << p->dp->index) & BRCM_IG_DSTMAP1_MASK;

return skb;

out_free:
kfree_skb(skb);
return NULL;
}

static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
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8 changes: 2 additions & 6 deletions net/dsa/tag_dsa.c
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev)
*/
if (skb->protocol == htons(ETH_P_8021Q)) {
if (skb_cow_head(skb, 0) < 0)
goto out_free;
return NULL;

/*
* Construct tagged FROM_CPU DSA tag from 802.1q tag.
Expand All @@ -46,7 +46,7 @@ static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev)
}
} else {
if (skb_cow_head(skb, DSA_HLEN) < 0)
goto out_free;
return NULL;
skb_push(skb, DSA_HLEN);

memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
Expand All @@ -62,10 +62,6 @@ static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev)
}

return skb;

out_free:
kfree_skb(skb);
return NULL;
}

static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev,
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8 changes: 2 additions & 6 deletions net/dsa/tag_edsa.c
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ static struct sk_buff *edsa_xmit(struct sk_buff *skb, struct net_device *dev)
*/
if (skb->protocol == htons(ETH_P_8021Q)) {
if (skb_cow_head(skb, DSA_HLEN) < 0)
goto out_free;
return NULL;
skb_push(skb, DSA_HLEN);

memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
Expand All @@ -55,7 +55,7 @@ static struct sk_buff *edsa_xmit(struct sk_buff *skb, struct net_device *dev)
}
} else {
if (skb_cow_head(skb, EDSA_HLEN) < 0)
goto out_free;
return NULL;
skb_push(skb, EDSA_HLEN);

memmove(skb->data, skb->data + EDSA_HLEN, 2 * ETH_ALEN);
Expand All @@ -75,10 +75,6 @@ static struct sk_buff *edsa_xmit(struct sk_buff *skb, struct net_device *dev)
}

return skb;

out_free:
kfree_skb(skb);
return NULL;
}

static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev,
Expand Down
4 changes: 1 addition & 3 deletions net/dsa/tag_ksz.c
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Original file line number Diff line number Diff line change
Expand Up @@ -46,10 +46,8 @@ static struct sk_buff *ksz_xmit(struct sk_buff *skb, struct net_device *dev)
} else {
nskb = alloc_skb(NET_IP_ALIGN + skb->len +
padlen + KSZ_INGRESS_TAG_LEN, GFP_ATOMIC);
if (!nskb) {
kfree_skb(skb);
if (!nskb)
return NULL;
}
skb_reserve(nskb, NET_IP_ALIGN);

skb_reset_mac_header(nskb);
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5 changes: 1 addition & 4 deletions net/dsa/tag_lan9303.c
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,7 @@ static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev)
if (skb_cow_head(skb, LAN9303_TAG_LEN) < 0) {
dev_dbg(&dev->dev,
"Cannot make room for the special tag. Dropping packet\n");
goto out_free;
return NULL;
}

/* provide 'LAN9303_TAG_LEN' bytes additional space */
Expand All @@ -66,9 +66,6 @@ static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev)
lan9303_tag[1] = htons(p->dp->index | BIT(4));

return skb;
out_free:
kfree_skb(skb);
return NULL;
}

static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
Expand Down
6 changes: 1 addition & 5 deletions net/dsa/tag_mtk.c
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@ static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
u8 *mtk_tag;

if (skb_cow_head(skb, MTK_HDR_LEN) < 0)
goto out_free;
return NULL;

skb_push(skb, MTK_HDR_LEN);

Expand All @@ -41,10 +41,6 @@ static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
mtk_tag[3] = 0;

return skb;

out_free:
kfree_skb(skb);
return NULL;
}

static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
Expand Down
6 changes: 1 addition & 5 deletions net/dsa/tag_qca.c
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,7 @@ static struct sk_buff *qca_tag_xmit(struct sk_buff *skb, struct net_device *dev)
dev->stats.tx_bytes += skb->len;

if (skb_cow_head(skb, 0) < 0)
goto out_free;
return NULL;

skb_push(skb, QCA_HDR_LEN);

Expand All @@ -60,10 +60,6 @@ static struct sk_buff *qca_tag_xmit(struct sk_buff *skb, struct net_device *dev)
*phdr = htons(hdr);

return skb;

out_free:
kfree_skb(skb);
return NULL;
}

static struct sk_buff *qca_tag_rcv(struct sk_buff *skb, struct net_device *dev,
Expand Down
4 changes: 1 addition & 3 deletions net/dsa/tag_trailer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -32,10 +32,8 @@ static struct sk_buff *trailer_xmit(struct sk_buff *skb, struct net_device *dev)
padlen = 60 - skb->len;

nskb = alloc_skb(NET_IP_ALIGN + skb->len + padlen + 4, GFP_ATOMIC);
if (nskb == NULL) {
kfree_skb(skb);
if (!nskb)
return NULL;
}
skb_reserve(nskb, NET_IP_ALIGN);

skb_reset_mac_header(nskb);
Expand Down

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