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[NET]: Avoid allocating skb in skb_pad

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First of all it is unnecessary to allocate a new skb in skb_pad since
the existing one is not shared.  More importantly, our hard_start_xmit
interface does not allow a new skb to be allocated since that breaks
requeueing.

This patch uses pskb_expand_head to expand the existing skb and linearize
it if needed.  Actually, someone should sift through every instance of
skb_pad on a non-linear skb as they do not fit the reasons why this was
originally created.

Incidentally, this fixes a minor bug when the skb is cloned (tcpdump,
TCP, etc.).  As it is skb_pad will simply write over a cloned skb.  Because
of the position of the write it is unlikely to cause problems but still
it's best if we don't do it.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2006-06-23 02:06:41 -07:00 committed by David S. Miller
parent 5fa21d821f
commit 5b057c6b1a
36 changed files with 74 additions and 103 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/net/3c527.c
View File

@ -1031,8 +1031,7 @@ static int mc32_send_packet(struct sk_buff *skb, struct net_device *dev)
return 1;
}
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL) {
if (skb_padto(skb, ETH_ZLEN)) {
netif_wake_queue(dev);
return 0;
}

3
drivers/net/82596.c
View File

@ -1070,8 +1070,7 @@ static int i596_start_xmit(struct sk_buff *skb, struct net_device *dev)
skb->len, (unsigned int)skb->data));
if (skb->len < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
length = ETH_ZLEN;
}

3
drivers/net/a2065.c
View File

@ -573,8 +573,7 @@ static int lance_start_xmit (struct sk_buff *skb, struct net_device *dev)
if (len < ETH_ZLEN) {
len = ETH_ZLEN;
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
}

3
drivers/net/ariadne.c
View File

@ -607,8 +607,7 @@ static int ariadne_start_xmit(struct sk_buff *skb, struct net_device *dev)
/* FIXME: is the 79C960 new enough to do its own padding right ? */
if (skb->len < ETH_ZLEN)
{
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
len = ETH_ZLEN;
}

3
drivers/net/arm/ether1.c
View File

@ -700,8 +700,7 @@ ether1_sendpacket (struct sk_buff *skb, struct net_device *dev)
}
if (skb->len < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
goto out;
}

3
drivers/net/arm/ether3.c
View File

@ -518,8 +518,7 @@ ether3_sendpacket(struct sk_buff *skb, struct net_device *dev)
length = (length + 1) & ~1;
if (length != skb->len) {
skb = skb_padto(skb, length);
if (skb == NULL)
if (skb_padto(skb, length))
goto out;
}

3
drivers/net/atarilance.c
View File

@ -804,8 +804,7 @@ static int lance_start_xmit( struct sk_buff *skb, struct net_device *dev )
++len;
if (len > skb->len) {
skb = skb_padto(skb, len);
if (skb == NULL)
if (skb_padto(skb, len))
return 0;
}

3
drivers/net/cassini.c
View File

@ -2915,8 +2915,7 @@ static int cas_start_xmit(struct sk_buff *skb, struct net_device *dev)
*/
static int ring;
skb = skb_padto(skb, cp->min_frame_size);
if (!skb)
if (skb_padto(skb, cp->min_frame_size))
return 0;
/* XXX: we need some higher-level QoS hooks to steer packets to

3
drivers/net/declance.c
View File

@ -885,8 +885,7 @@ static int lance_start_xmit(struct sk_buff *skb, struct net_device *dev)
len = skblen;
if (len < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
len = ETH_ZLEN;
}

7
drivers/net/depca.c
View File

@ -938,11 +938,8 @@ static int depca_start_xmit(struct sk_buff *skb, struct net_device *dev)
if (skb->len < 1)
goto out;
if (skb->len < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
goto out;
}
if (skb_padto(skb, ETH_ZLEN))
goto out;
netif_stop_queue(dev);

3
drivers/net/eepro.c
View File

@ -1154,8 +1154,7 @@ static int eepro_send_packet(struct sk_buff *skb, struct net_device *dev)
printk(KERN_DEBUG "%s: entering eepro_send_packet routine.\n", dev->name);
if (length < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
length = ETH_ZLEN;
}

3
drivers/net/eexpress.c
View File

@ -677,8 +677,7 @@ static int eexp_xmit(struct sk_buff *buf, struct net_device *dev)
#endif
if (buf->len < ETH_ZLEN) {
buf = skb_padto(buf, ETH_ZLEN);
if (buf == NULL)
if (skb_padto(buf, ETH_ZLEN))
return 0;
length = ETH_ZLEN;
}

7
drivers/net/epic100.c
View File

@ -1027,11 +1027,8 @@ static int epic_start_xmit(struct sk_buff *skb, struct net_device *dev)
u32 ctrl_word;
unsigned long flags;
if (skb->len < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
return 0;
}
if (skb_padto(skb, ETH_ZLEN))
return 0;
/* Caution: the write order is important here, set the field with the
"ownership" bit last. */

3
drivers/net/eth16i.c
View File

@ -1064,8 +1064,7 @@ static int eth16i_tx(struct sk_buff *skb, struct net_device *dev)
unsigned long flags;
if (length < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
length = ETH_ZLEN;
}

7
drivers/net/hp100.c
View File

@ -1487,11 +1487,8 @@ static int hp100_start_xmit_bm(struct sk_buff *skb, struct net_device *dev)
if (skb->len <= 0)
return 0;
if (skb->len < ETH_ZLEN && lp->chip == HP100_CHIPID_SHASTA) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
return 0;
}
if (lp->chip == HP100_CHIPID_SHASTA && skb_padto(skb, ETH_ZLEN))
return 0;
/* Get Tx ring tail pointer */
if (lp->txrtail->next == lp->txrhead) {

3
drivers/net/lance.c
View File

@ -968,8 +968,7 @@ static int lance_start_xmit(struct sk_buff *skb, struct net_device *dev)
/* The old LANCE chips doesn't automatically pad buffers to min. size. */
if (chip_table[lp->chip_version].flags & LANCE_MUST_PAD) {
if (skb->len < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
goto out;
lp->tx_ring[entry].length = -ETH_ZLEN;
}

3
drivers/net/lasi_82596.c
View File

@ -1083,8 +1083,7 @@ static int i596_start_xmit(struct sk_buff *skb, struct net_device *dev)
skb->len, skb->data));
if (length < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
length = ETH_ZLEN;
}

3
drivers/net/lp486e.c
View File

@ -877,8 +877,7 @@ static int i596_start_xmit (struct sk_buff *skb, struct net_device *dev) {
length = skb->len;
if (length < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
length = ETH_ZLEN;
}

3
drivers/net/myri10ge/myri10ge.c
View File

@ -1939,8 +1939,7 @@ again:
/* pad frames to at least ETH_ZLEN bytes */
if (unlikely(skb->len < ETH_ZLEN)) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL) {
if (skb_padto(skb, ETH_ZLEN)) {
/* The packet is gone, so we must
* return 0 */
mgp->stats.tx_dropped += 1;

3
drivers/net/pcmcia/fmvj18x_cs.c
View File

@ -831,8 +831,7 @@ static int fjn_start_xmit(struct sk_buff *skb, struct net_device *dev)
if (length < ETH_ZLEN)
{
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
length = ETH_ZLEN;
}

3
drivers/net/pcmcia/xirc2ps_cs.c
View File

@ -1374,8 +1374,7 @@ do_start_xmit(struct sk_buff *skb, struct net_device *dev)
*/
if (pktlen < ETH_ZLEN)
{
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
pktlen = ETH_ZLEN;
}

3
drivers/net/r8169.c
View File

@ -2222,8 +2222,7 @@ static int rtl8169_start_xmit(struct sk_buff *skb, struct net_device *dev)
len = skb->len;
if (unlikely(len < ETH_ZLEN)) {
skb = skb_padto(skb, ETH_ZLEN);
if (!skb)
if (skb_padto(skb, ETH_ZLEN))
goto err_update_stats;
len = ETH_ZLEN;
}

3
drivers/net/seeq8005.c
View File

@ -396,8 +396,7 @@ static int seeq8005_send_packet(struct sk_buff *skb, struct net_device *dev)
unsigned char *buf;
if (length < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
length = ETH_ZLEN;
}

3
drivers/net/sis190.c
View File

@ -1156,8 +1156,7 @@ static int sis190_start_xmit(struct sk_buff *skb, struct net_device *dev)
dma_addr_t mapping;
if (unlikely(skb->len < ETH_ZLEN)) {
skb = skb_padto(skb, ETH_ZLEN);
if (!skb) {
if (skb_padto(skb, ETH_ZLEN)) {
tp->stats.tx_dropped++;
goto out;
}

2
drivers/net/sk98lin/skge.c
View File

@ -1525,7 +1525,7 @@ struct sk_buff *pMessage) /* pointer to send-message */
** This is to resolve faulty padding by the HW with 0xaa bytes.
*/
if (BytesSend < C_LEN_ETHERNET_MINSIZE) {
if ((pMessage = skb_padto(pMessage, C_LEN_ETHERNET_MINSIZE)) == NULL) {
if (skb_padto(pMessage, C_LEN_ETHERNET_MINSIZE)) {
spin_unlock_irqrestore(&pTxPort->TxDesRingLock, Flags);
return 0;
}

3
drivers/net/skge.c
View File

@ -2310,8 +2310,7 @@ static int skge_xmit_frame(struct sk_buff *skb, struct net_device *dev)
u64 map;
unsigned long flags;
skb = skb_padto(skb, ETH_ZLEN);
if (!skb)
if (skb_padto(skb, ETH_ZLEN))
return NETDEV_TX_OK;
if (!spin_trylock_irqsave(&skge->tx_lock, flags))

3
drivers/net/smc9194.c
View File

@ -523,8 +523,7 @@ static int smc_wait_to_send_packet( struct sk_buff * skb, struct net_device * de
length = skb->len;
if (length < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL) {
if (skb_padto(skb, ETH_ZLEN)) {
netif_wake_queue(dev);
return 0;
}

3
drivers/net/sonic.c
View File

@ -231,8 +231,7 @@ static int sonic_send_packet(struct sk_buff *skb, struct net_device *dev)
length = skb->len;
if (length < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
length = ETH_ZLEN;
}

3
drivers/net/starfire.c
View File

@ -1349,8 +1349,7 @@ static int start_tx(struct sk_buff *skb, struct net_device *dev)
#if defined(ZEROCOPY) && defined(HAS_BROKEN_FIRMWARE)
if (skb->ip_summed == CHECKSUM_HW) {
skb = skb_padto(skb, (skb->len + PADDING_MASK) & ~PADDING_MASK);
if (skb == NULL)
if (skb_padto(skb, (skb->len + PADDING_MASK) & ~PADDING_MASK))
return NETDEV_TX_OK;
}
#endif /* ZEROCOPY && HAS_BROKEN_FIRMWARE */

7
drivers/net/via-rhine.c
View File

@ -1284,11 +1284,8 @@ static int rhine_start_tx(struct sk_buff *skb, struct net_device *dev)
/* Calculate the next Tx descriptor entry. */
entry = rp->cur_tx % TX_RING_SIZE;
if (skb->len < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
return 0;
}
if (skb_padto(skb, ETH_ZLEN))
return 0;
rp->tx_skbuff[entry] = skb;

3
drivers/net/wireless/ray_cs.c
View File

@ -924,8 +924,7 @@ static int ray_dev_start_xmit(struct sk_buff *skb, struct net_device *dev)
if (length < ETH_ZLEN)
{
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
length = ETH_ZLEN;
}

7
drivers/net/wireless/wavelan_cs.c
View File

@ -3194,11 +3194,8 @@ wavelan_packet_xmit(struct sk_buff * skb,
* and we don't have the Ethernet specific requirement of beeing
* able to detect collisions, therefore in theory we don't really
* need to pad. Jean II */
if (skb->len < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
return 0;
}
if (skb_padto(skb, ETH_ZLEN))
return 0;
wv_packet_write(dev, skb->data, skb->len);

12
drivers/net/yellowfin.c
View File

@ -862,13 +862,11 @@ static int yellowfin_start_xmit(struct sk_buff *skb, struct net_device *dev)
/* Fix GX chipset errata. */
if (cacheline_end > 24 || cacheline_end == 0) {
len = skb->len + 32 - cacheline_end + 1;
if (len != skb->len)
skb = skb_padto(skb, len);
}
if (skb == NULL) {
yp->tx_skbuff[entry] = NULL;
netif_wake_queue(dev);
return 0;
if (skb_padto(skb, len)) {
yp->tx_skbuff[entry] = NULL;
netif_wake_queue(dev);
return 0;
}
}
}
yp->tx_skbuff[entry] = skb;

3
drivers/net/znet.c
View File

@ -544,8 +544,7 @@ static int znet_send_packet(struct sk_buff *skb, struct net_device *dev)
printk(KERN_DEBUG "%s: ZNet_send_packet.\n", dev->name);
if (length < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
if (skb_padto(skb, ETH_ZLEN))
return 0;
length = ETH_ZLEN;
}

11
include/linux/skbuff.h
View File

@ -345,7 +345,7 @@ extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
int newheadroom, int newtailroom,
gfp_t priority);
extern struct sk_buff * skb_pad(struct sk_buff *skb, int pad);
extern int skb_pad(struct sk_buff *skb, int pad);
#define dev_kfree_skb(a) kfree_skb(a)
extern void skb_over_panic(struct sk_buff *skb, int len,
void *here);
@ -1122,16 +1122,15 @@ static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
*
* Pads up a buffer to ensure the trailing bytes exist and are
* blanked. If the buffer already contains sufficient data it
* is untouched. Returns the buffer, which may be a replacement
* for the original, or NULL for out of memory - in which case
* the original buffer is still freed.
* is untouched. Otherwise it is extended. Returns zero on
* success. The skb is freed on error.
*/
static inline struct sk_buff *skb_padto(struct sk_buff *skb, unsigned int len)
static inline int skb_padto(struct sk_buff *skb, unsigned int len)
{
unsigned int size = skb->len;
if (likely(size >= len))
return skb;
return 0;
return skb_pad(skb, len-size);
}

36
net/core/skbuff.c
View File

@ -781,24 +781,40 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
* filled. Used by network drivers which may DMA or transfer data
* beyond the buffer end onto the wire.
*
* May return NULL in out of memory cases.
* May return error in out of memory cases. The skb is freed on error.
*/
struct sk_buff *skb_pad(struct sk_buff *skb, int pad)
int skb_pad(struct sk_buff *skb, int pad)
{
struct sk_buff *nskb;
int err;
int ntail;
/* If the skbuff is non linear tailroom is always zero.. */
if (skb_tailroom(skb) >= pad) {
if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
memset(skb->data+skb->len, 0, pad);
return skb;
return 0;
}
nskb = skb_copy_expand(skb, skb_headroom(skb), skb_tailroom(skb) + pad, GFP_ATOMIC);
ntail = skb->data_len + pad - (skb->end - skb->tail);
if (likely(skb_cloned(skb) || ntail > 0)) {
err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
if (unlikely(err))
goto free_skb;
}
/* FIXME: The use of this function with non-linear skb's really needs
* to be audited.
*/
err = skb_linearize(skb);
if (unlikely(err))
goto free_skb;
memset(skb->data + skb->len, 0, pad);
return 0;
free_skb:
kfree_skb(skb);
if (nskb)
memset(nskb->data+nskb->len, 0, pad);
return nskb;
return err;
}
/* Trims skb to length len. It can change skb pointers.