[PATCH 3.4 032/214] skb: Add inline helper for getting the skb end offset from head

Greg Kroah-Hartman
2014-06-05T04:20:09Z

From: Alexander Duyck <alexander.h.duyck@intel.com>

[ Upstream commit ec47ea82477404631d49b8e568c71826c9b663ac ]

With the recent changes for how we compute the skb truesize it occurs to me
we are probably going to have a lot of calls to skb_end_pointer -
skb->head. Instead of running all over the place doing that it would make
more sense to just make it a separate inline skb_end_offset(skb) that way
we can return the correct value without having gcc having to do all the
optimization to cancel out skb->head - skb->head.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/atm/ambassador.c | 2 +-
drivers/atm/idt77252.c | 2 +-
drivers/net/wimax/i2400m/usb-rx.c | 2 +-
drivers/staging/octeon/ethernet-tx.c | 2 +-
include/linux/skbuff.h | 12 +++++++++++-
net/core/skbuff.c | 9 ++++-----
6 files changed, 19 insertions(+), 10 deletions(-)

--- a/drivers/atm/ambassador.c
+++ b/drivers/atm/ambassador.c
@@ -802,7 +802,7 @@ static void fill_rx_pool (amb_dev * dev,
}
// cast needed as there is no %? for pointer differences
PRINTD (DBG_SKB, "allocated skb at %p, head %p, area %li",
- skb, skb->head, (long) (skb_end_pointer(skb) - skb->head));
+ skb, skb->head, (long) skb_end_offset(skb));
rx.handle = virt_to_bus (skb);
rx.host_address = cpu_to_be32 (virt_to_bus (skb->data));
if (rx_give (dev, &rx, pool))
--- a/drivers/atm/idt77252.c
+++ b/drivers/atm/idt77252.c
@@ -1258,7 +1258,7 @@ idt77252_rx_raw(struct idt77252_dev *car
tail = readl(SAR_REG_RAWCT);

pci_dma_sync_single_for_cpu(card->pcidev, IDT77252_PRV_PADDR(queue),
- skb_end_pointer(queue) - queue->head - 16,
+ skb_end_offset(queue) - 16,
PCI_DMA_FROMDEVICE);

while (head != tail) {
--- a/drivers/net/wimax/i2400m/usb-rx.c
+++ b/drivers/net/wimax/i2400m/usb-rx.c
@@ -277,7 +277,7 @@ retry:
d_printf(1, dev, "RX: size changed to %d, received %d, "
"copied %d, capacity %ld\n",
rx_size, read_size, rx_skb->len,
- (long) (skb_end_pointer(new_skb) - new_skb->head));
+ (long) skb_end_offset(new_skb));
goto retry;
}
/* In most cases, it happens due to the hardware scheduling a
--- a/drivers/staging/octeon/ethernet-tx.c
+++ b/drivers/staging/octeon/ethernet-tx.c
@@ -345,7 +345,7 @@ int cvm_oct_xmit(struct sk_buff *skb, st
}
if (unlikely
(skb->truesize !=
- sizeof(*skb) + skb_end_pointer(skb) - skb->head)) {
+ sizeof(*skb) + skb_end_offset(skb))) {
/*
printk("TX buffer truesize has been changed\n");
*/
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -640,11 +640,21 @@ static inline unsigned char *skb_end_poi
{
return skb->head + skb->end;
}
+
+static inline unsigned int skb_end_offset(const struct sk_buff *skb)
+{
+ return skb->end;
+}
#else
static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
{
return skb->end;
}
+
+static inline unsigned int skb_end_offset(const struct sk_buff *skb)
+{
+ return skb->end - skb->head;
+}
#endif

/* Internal */
@@ -2574,7 +2584,7 @@ static inline bool skb_is_recycleable(co
return false;

skb_size = SKB_DATA_ALIGN(skb_size + NET_SKB_PAD);
- if (skb_end_pointer(skb) - skb->head < skb_size)
+ if (skb_end_offset(skb) < skb_size)
return false;

if (skb_shared(skb) || skb_cloned(skb))
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -821,7 +821,7 @@ static void copy_skb_header(struct sk_bu
struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
{
int headerlen = skb_headroom(skb);
- unsigned int size = (skb_end_pointer(skb) - skb->head) + skb->data_len;
+ unsigned int size = skb_end_offset(skb) + skb->data_len;
struct sk_buff *n = alloc_skb(size, gfp_mask);

if (!n)
@@ -922,7 +922,7 @@ int pskb_expand_head(struct sk_buff *skb
{
int i;
u8 *data;
- int size = nhead + (skb_end_pointer(skb) - skb->head) + ntail;
+ int size = nhead + skb_end_offset(skb) + ntail;
long off;
bool fastpath;

@@ -2721,14 +2721,13 @@ struct sk_buff *skb_segment(struct sk_bu
if (unlikely(!nskb))
goto err;

- hsize = skb_end_pointer(nskb) - nskb->head;
+ hsize = skb_end_offset(nskb);
if (skb_cow_head(nskb, doffset + headroom)) {
kfree_skb(nskb);
goto err;
}

- nskb->truesize += skb_end_pointer(nskb) - nskb->head -
- hsize;
+ nskb->truesize += skb_end_offset(nskb) - hsize;
skb_release_head_state(nskb);
__skb_push(nskb, doffset);
} else {