[PATCH 75/75] net: return a *const* struct page from skb_frag_page.

Ian Campbell
2011-08-19T13:30:32Z

This attempts to catch bare uses of get/put_page (which take a non-const struct
page) on skb paged fragments.

Add __skb_frag_page for those callers which really need a non-const reference
to the page.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>
Cc: netdev@vger.kernel.org
---
drivers/infiniband/ulp/ipoib/ipoib_cm.c | 4 ++--
drivers/infiniband/ulp/ipoib/ipoib_ib.c | 2 +-
drivers/net/bnx2.c | 2 +-
drivers/net/cassini.c | 2 +-
drivers/net/e1000/e1000_main.c | 2 +-
drivers/net/jme.c | 2 +-
drivers/net/niu.c | 2 +-
drivers/net/xen-netback/netback.c | 2 +-
drivers/net/xen-netfront.c | 4 ++--
drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 2 +-
drivers/scsi/cxgbi/libcxgbi.c | 2 +-
drivers/scsi/fcoe/fcoe_transport.c | 2 +-
include/linux/skbuff.h | 30 +++++++++++++++++++++---------
net/core/skbuff.c | 6 ++++--
net/core/user_dma.c | 2 +-
net/ipv4/tcp.c | 2 +-
16 files changed, 41 insertions(+), 27 deletions(-)

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
index 67a477b..be21cc2 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
@@ -537,8 +537,8 @@ static void skb_put_frags(struct sk_buff *skb, unsigned int hdr_space,

if (length == 0) {
/* don't need this page */
- skb_fill_page_desc(toskb, i, skb_frag_page(frag),
- 0, PAGE_SIZE);
+ skb_fill_page_desc(toskb, i, __skb_frag_page(frag),
+ 0, PAGE_SIZE);/* XXX */
--skb_shinfo(skb)->nr_frags;
} else {
size = min(length, (unsigned) PAGE_SIZE);
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_ib.c b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
index 00435be..003fc75 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
@@ -324,7 +324,7 @@ static int ipoib_dma_map_tx(struct ib_device *ca,
for (i = 0; i < skb_shinfo(skb)->nr_frags; ++i) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
mapping[i + off] = ib_dma_map_page(ca,
- skb_frag_page(frag),
+ __skb_frag_page(frag),
frag->page_offset, frag->size,
DMA_TO_DEVICE);
if (unlikely(ib_dma_mapping_error(ca, mapping[i + off])))
diff --git a/drivers/net/bnx2.c b/drivers/net/bnx2.c
index 005dd81..e1e96f5 100644
--- a/drivers/net/bnx2.c
+++ b/drivers/net/bnx2.c
@@ -2929,7 +2929,7 @@ bnx2_reuse_rx_skb_pages(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr,

shinfo = skb_shinfo(skb);
shinfo->nr_frags--;
- page = skb_frag_page(&shinfo->frags[shinfo->nr_frags]);
+ page = __skb_frag_page(&shinfo->frags[shinfo->nr_frags]);
__skb_frag_set_page(&shinfo->frags[shinfo->nr_frags], NULL);

cons_rx_pg->page = page;
diff --git a/drivers/net/cassini.c b/drivers/net/cassini.c
index de5c7590..0f21ab5 100644
--- a/drivers/net/cassini.c
+++ b/drivers/net/cassini.c
@@ -2842,7 +2842,7 @@ static inline int cas_xmit_tx_ringN(struct cas *cp, int ring,
ctrl, 0);
entry = TX_DESC_NEXT(ring, entry);

- addr = cas_page_map(skb_frag_page(fragp));
+ addr = cas_page_map(__skb_frag_page(fragp));
memcpy(tx_tiny_buf(cp, ring, entry),
addr + fragp->page_offset + len - tabort,
tabort);
diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index c96770c..34ad431 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -2927,7 +2927,7 @@ static int e1000_tx_map(struct e1000_adapter *adapter,
* Avoid terminating buffers within evenly-aligned
* dwords. */
bufend = (unsigned long)
- page_to_phys(skb_frag_page(frag));
+ page_to_phys(__skb_frag_page(frag));
bufend += offset + size - 1;
if (unlikely(adapter->pcix_82544 &&
!(bufend & 4) &&
diff --git a/drivers/net/jme.c b/drivers/net/jme.c
index 610b837..c0fd39e 100644
--- a/drivers/net/jme.c
+++ b/drivers/net/jme.c
@@ -1929,7 +1929,7 @@ jme_map_tx_skb(struct jme_adapter *jme, struct sk_buff *skb, int idx)
ctxbi = txbi + ((idx + i + 2) & (mask));

jme_fill_tx_map(jme->pdev, ctxdesc, ctxbi,
- skb_frag_page(frag),
+ __skb_frag_page(frag),
frag->page_offset, frag->size, hidma);
}

diff --git a/drivers/net/niu.c b/drivers/net/niu.c
index 0191712..22a7536 100644
--- a/drivers/net/niu.c
+++ b/drivers/net/niu.c
@@ -6736,7 +6736,7 @@ static netdev_tx_t niu_start_xmit(struct sk_buff *skb,
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

len = frag->size;
- mapping = np->ops->map_page(np->device, skb_frag_page(frag),
+ mapping = np->ops->map_page(np->device, __skb_frag_page(frag),
frag->page_offset, len,
DMA_TO_DEVICE);

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 3068f67..824bd42 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -522,7 +522,7 @@ static int netbk_gop_skb(struct sk_buff *skb,

for (i = 0; i < nr_frags; i++) {
netbk_gop_frag_copy(vif, skb, npo,
- skb_frag_page(&skb_shinfo(skb)->frags[i]),
+ __skb_frag_page(&skb_shinfo(skb)->frags[i]),
skb_shinfo(skb)->frags[i].size,
skb_shinfo(skb)->frags[i].page_offset,
&head);
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 882a957..d93a1c6 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -770,7 +770,7 @@ static RING_IDX xennet_fill_frags(struct netfront_info *np,
RING_GET_RESPONSE(&np->rx, ++cons);
skb_frag_t *nfrag = &skb_shinfo(nskb)->frags[0];

- __skb_frag_set_page(frag, skb_frag_page(nfrag));
+ __skb_frag_set_page(frag, __skb_frag_page(nfrag));
frag->page_offset = rx->offset;
frag->size = rx->status;

@@ -956,7 +956,7 @@ err:
}

NETFRONT_SKB_CB(skb)->page =
- skb_frag_page(&skb_shinfo(skb)->frags[0]);
+ __skb_frag_page(&skb_shinfo(skb)->frags[0]);
NETFRONT_SKB_CB(skb)->offset = rx->offset;

len = rx->status;
diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
index 2c780a7..7828cb9 100644
--- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
@@ -302,7 +302,7 @@ static int bnx2fc_xmit(struct fc_lport *lport, struct fc_frame *fp)
return -ENOMEM;
}
frag = &skb_shinfo(skb)->frags[skb_shinfo(skb)->nr_frags - 1];
- cp = kmap_atomic(skb_frag_page(frag), KM_SKB_DATA_SOFTIRQ)
+ cp = kmap_atomic(__skb_frag_page(frag), KM_SKB_DATA_SOFTIRQ)
+ frag->page_offset;
} else {
cp = (struct fcoe_crc_eof *)skb_put(skb, tlen);
diff --git a/drivers/scsi/cxgbi/libcxgbi.c b/drivers/scsi/cxgbi/libcxgbi.c
index 43cc6c6..ed3d48d 100644
--- a/drivers/scsi/cxgbi/libcxgbi.c
+++ b/drivers/scsi/cxgbi/libcxgbi.c
@@ -1948,7 +1948,7 @@ int cxgbi_conn_init_pdu(struct iscsi_task *task, unsigned int offset,

/* data fits in the skb's headroom */
for (i = 0; i < tdata->nr_frags; i++, frag++) {
- char *src = kmap_atomic(skb_frag_page(frag),
+ char *src = kmap_atomic(__skb_frag_page(frag),
KM_SOFTIRQ0);

memcpy(dst, src+frag->page_offset, frag->size);
diff --git a/drivers/scsi/fcoe/fcoe_transport.c b/drivers/scsi/fcoe/fcoe_transport.c
index f6613f9..40243ce 100644
--- a/drivers/scsi/fcoe/fcoe_transport.c
+++ b/drivers/scsi/fcoe/fcoe_transport.c
@@ -109,7 +109,7 @@ u32 fcoe_fc_crc(struct fc_frame *fp)
while (len > 0) {
clen = min(len, PAGE_SIZE - (off & ~PAGE_MASK));
data = kmap_atomic(
- skb_frag_page(frag) + (off >> PAGE_SHIFT),
+ __skb_frag_page(frag) + (off >> PAGE_SHIFT),
KM_SKB_DATA_SOFTIRQ);
crc = crc32(crc, data + (off & ~PAGE_MASK), clen);
kunmap_atomic(data, KM_SKB_DATA_SOFTIRQ);
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 0328428..40dde83 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1698,12 +1698,24 @@ static inline void netdev_free_page(struct net_device *dev, struct page *page)
}

/**
- * skb_frag_page - retrieve the page refered to by a paged fragment
+ * __skb_frag_page - retrieve the page refered to by a paged fragment
* @frag: the paged fragment
*
- * Returns the &struct page associated with @frag.
+ * Returns the &struct page associated with @frag. Where possible you
+ * should use skb_frag_page() which returns a const &struct page.
*/
-static inline struct page *skb_frag_page(const skb_frag_t *frag)
+static inline struct page *__skb_frag_page(const skb_frag_t *frag)
+{
+ return frag->page.p;
+}
+
+/**
+ * __skb_frag_page - retrieve the page refered to by a paged fragment
+ * @frag: the paged fragment
+ *
+ * Returns the &struct page associated with @frag as a const.
+ */
+static inline const struct page *skb_frag_page(const skb_frag_t *frag)
{
return frag->page.p;
}
@@ -1723,7 +1735,7 @@ static inline void __skb_frag_ref(skb_frag_t *frag)
skb_frag_destructor_ref(frag->page.destructor);
return;
}
- get_page(skb_frag_page(frag));
+ get_page(__skb_frag_page(frag));
}

/**
@@ -1750,7 +1762,7 @@ static inline void __skb_frag_unref(skb_frag_t *frag)
skb_frag_destructor_unref(frag->page.destructor);
return;
}
- put_page(skb_frag_page(frag));
+ put_page(__skb_frag_page(frag));
}

/**
@@ -1827,7 +1839,7 @@ static inline void *skb_frag_kmap_atomic(const skb_frag_t *frag)

local_bh_disable();
#endif
- return kmap_atomic(skb_frag_page(frag), KM_SKB_DATA_SOFTIRQ);
+ return kmap_atomic(__skb_frag_page(frag), KM_SKB_DATA_SOFTIRQ);
}

static inline void skb_frag_kunmap_atomic(void *vaddr)
@@ -1846,7 +1858,7 @@ static inline void skb_frag_kunmap_atomic(void *vaddr)
*/
static inline void *skb_frag_kmap(skb_frag_t *frag)
{
- return kmap(skb_frag_page(frag));
+ return kmap(__skb_frag_page(frag));
}

/**
@@ -1857,7 +1869,7 @@ static inline void *skb_frag_kmap(skb_frag_t *frag)
*/
static inline void skb_frag_kunmap(skb_frag_t *frag)
{
- kunmap(skb_frag_page(frag));
+ kunmap(__skb_frag_page(frag));
}

/**
@@ -1876,7 +1888,7 @@ static inline dma_addr_t skb_frag_dma_map(struct device *dev,
size_t offset, size_t size,
enum dma_data_direction dir)
{
- return dma_map_page(dev, skb_frag_page(frag),
+ return dma_map_page(dev, __skb_frag_page(frag),
frag->page_offset + offset, size, dir);
}

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index d09d312..fbce6e7 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1628,7 +1628,8 @@ static int __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];

- if (__splice_segment(skb_frag_page(f),
+ /* XXX */
+ if (__splice_segment(__skb_frag_page(f),
f->page_offset, f->size,
offset, len, skb, spd, 0, sk, pipe))
return 1;
@@ -2940,7 +2941,8 @@ __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)

if (copy > len)
copy = len;
- sg_set_page(&sg[elt], skb_frag_page(frag), copy,
+ /* XXX */
+ sg_set_page(&sg[elt], __skb_frag_page(frag), copy,
frag->page_offset+offset-start);
elt++;
if (!(len -= copy))
diff --git a/net/core/user_dma.c b/net/core/user_dma.c
index 34e9664..d22ec3e 100644
--- a/net/core/user_dma.c
+++ b/net/core/user_dma.c
@@ -78,7 +78,7 @@ int dma_skb_copy_datagram_iovec(struct dma_chan *chan,
copy = end - offset;
if (copy > 0) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
- struct page *page = skb_frag_page(frag);
+ struct page *page = __skb_frag_page(frag); /* XXX */

if (copy > len)
copy = len;
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 5dd6d50..0b715bb 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3043,7 +3043,7 @@ int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,

for (i = 0; i < shi->nr_frags; ++i) {
const struct skb_frag_struct *f = &shi->frags[i];
- struct page *page = skb_frag_page(f);
+ struct page *page = __skb_frag_page(f); /* XXX */
sg_set_page(&sg, page, f->size, f->page_offset);
if (crypto_hash_update(desc, &sg, f->size))
return 1;
--
1.7.2.5