[PATCH 68/75] hv: netvsc: convert to SKB paged frag API.

Ian Campbell
2011-08-19T13:30:13Z

Cc: Hank Janssen <hjanssen@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Abhishek Kane <v-abkane@microsoft.com>
Cc: devel@driverdev.osuosl.org
Cc: linux-kernel@vger.kernel.org
---
drivers/net/cxgb4/sge.c | 14 +++++-----
drivers/net/cxgb4vf/sge.c | 18 ++++++------
drivers/net/mlx4/en_rx.c | 2 +-
drivers/scsi/cxgbi/libcxgbi.c | 2 +-
drivers/staging/hv/netvsc_drv.c | 2 +-
include/linux/skbuff.h | 54 ++++++++++++++++++++++++++++++++++++---
net/core/skbuff.c | 26 +++++++++++++++++-
7 files changed, 93 insertions(+), 25 deletions(-)

diff --git a/drivers/net/cxgb4/sge.c b/drivers/net/cxgb4/sge.c
index f1813b5..3e7c4b3 100644
--- a/drivers/net/cxgb4/sge.c
+++ b/drivers/net/cxgb4/sge.c
@@ -1416,7 +1416,7 @@ static inline void copy_frags(struct sk_buff *skb,
unsigned int n;

/* usually there's just one frag */
- skb_frag_set_page(skb, 0, gl->frags[0].page);
+ skb_frag_set_page(skb, 0, gl->frags[0].page.p); /* XXX */
ssi->frags[0].page_offset = gl->frags[0].page_offset + offset;
ssi->frags[0].size = gl->frags[0].size - offset;
ssi->nr_frags = gl->nfrags;
@@ -1425,7 +1425,7 @@ static inline void copy_frags(struct sk_buff *skb,
memcpy(&ssi->frags[1], &gl->frags[1], n * sizeof(skb_frag_t));

/* get a reference to the last page, we don't own it */
- get_page(gl->frags[n].page);
+ get_page(gl->frags[n].page.p); /* XXX */
}

/**
@@ -1482,7 +1482,7 @@ static void t4_pktgl_free(const struct pkt_gl *gl)
const skb_frag_t *p;

for (p = gl->frags, n = gl->nfrags - 1; n--; p++)
- put_page(p->page);
+ put_page(p->page.p); /* XXX */
}

/*
@@ -1635,7 +1635,7 @@ static void restore_rx_bufs(const struct pkt_gl *si, struct sge_fl *q,
else
q->cidx--;
d = &q->sdesc[q->cidx];
- d->page = si->frags[frags].page;
+ d->page = si->frags[frags].page.p; /* XXX */
d->dma_addr |= RX_UNMAPPED_BUF;
q->avail++;
}
@@ -1717,7 +1717,7 @@ static int process_responses(struct sge_rspq *q, int budget)
for (frags = 0, fp = si.frags; ; frags++, fp++) {
rsd = &rxq->fl.sdesc[rxq->fl.cidx];
bufsz = get_buf_size(rsd);
- fp->page = rsd->page;
+ fp->page.p = rsd->page; /* XXX */
fp->page_offset = q->offset;
fp->size = min(bufsz, len);
len -= fp->size;
@@ -1734,8 +1734,8 @@ static int process_responses(struct sge_rspq *q, int budget)
get_buf_addr(rsd),
fp->size, DMA_FROM_DEVICE);

- si.va = page_address(si.frags[0].page) +
- si.frags[0].page_offset;
+ si.va = page_address(si.frags[0].page.p) +
+ si.frags[0].page_offset; /* XXX */

prefetch(si.va);

diff --git a/drivers/net/cxgb4vf/sge.c b/drivers/net/cxgb4vf/sge.c
index 6d6060e..3688423 100644
--- a/drivers/net/cxgb4vf/sge.c
+++ b/drivers/net/cxgb4vf/sge.c
@@ -1397,7 +1397,7 @@ struct sk_buff *t4vf_pktgl_to_skb(const struct pkt_gl *gl,
skb_copy_to_linear_data(skb, gl->va, pull_len);

ssi = skb_shinfo(skb);
- skb_frag_set_page(skb, 0, gl->frags[0].page);
+ skb_frag_set_page(skb, 0, gl->frags[0].page.p); /* XXX */
ssi->frags[0].page_offset = gl->frags[0].page_offset + pull_len;
ssi->frags[0].size = gl->frags[0].size - pull_len;
if (gl->nfrags > 1)
@@ -1410,7 +1410,7 @@ struct sk_buff *t4vf_pktgl_to_skb(const struct pkt_gl *gl,
skb->truesize += skb->data_len;

/* Get a reference for the last page, we don't own it */
- get_page(gl->frags[gl->nfrags - 1].page);
+ get_page(gl->frags[gl->nfrags - 1].page.p); /* XXX */
}

out:
@@ -1430,7 +1430,7 @@ void t4vf_pktgl_free(const struct pkt_gl *gl)

frag = gl->nfrags - 1;
while (frag--)
- put_page(gl->frags[frag].page);
+ put_page(gl->frags[frag].page.p); /* XXX */
}

/**
@@ -1450,7 +1450,7 @@ static inline void copy_frags(struct sk_buff *skb,
unsigned int n;

/* usually there's just one frag */
- skb_frag_set_page(skb, 0, gl->frags[0].page);
+ skb_frag_set_page(skb, 0, gl->frags[0].page.p); /* XXX */
si->frags[0].page_offset = gl->frags[0].page_offset + offset;
si->frags[0].size = gl->frags[0].size - offset;
si->nr_frags = gl->nfrags;
@@ -1460,7 +1460,7 @@ static inline void copy_frags(struct sk_buff *skb,
memcpy(&si->frags[1], &gl->frags[1], n * sizeof(skb_frag_t));

/* get a reference to the last page, we don't own it */
- get_page(gl->frags[n].page);
+ get_page(gl->frags[n].page.p); /* XXX */
}

/**
@@ -1613,7 +1613,7 @@ static void restore_rx_bufs(const struct pkt_gl *gl, struct sge_fl *fl,
else
fl->cidx--;
sdesc = &fl->sdesc[fl->cidx];
- sdesc->page = gl->frags[frags].page;
+ sdesc->page = gl->frags[frags].page.p; /* XXX */
sdesc->dma_addr |= RX_UNMAPPED_BUF;
fl->avail++;
}
@@ -1701,7 +1701,7 @@ int process_responses(struct sge_rspq *rspq, int budget)
BUG_ON(rxq->fl.avail == 0);
sdesc = &rxq->fl.sdesc[rxq->fl.cidx];
bufsz = get_buf_size(sdesc);
- fp->page = sdesc->page;
+ fp->page.p = sdesc->page; /* XXX */
fp->page_offset = rspq->offset;
fp->size = min(bufsz, len);
len -= fp->size;
@@ -1719,8 +1719,8 @@ int process_responses(struct sge_rspq *rspq, int budget)
dma_sync_single_for_cpu(rspq->adapter->pdev_dev,
get_buf_addr(sdesc),
fp->size, DMA_FROM_DEVICE);
- gl.va = (page_address(gl.frags[0].page) +
- gl.frags[0].page_offset);
+ gl.va = (page_address(gl.frags[0].page.p) +
+ gl.frags[0].page_offset); /* XXX */
prefetch(gl.va);

/*
diff --git a/drivers/net/mlx4/en_rx.c b/drivers/net/mlx4/en_rx.c
index 0c26ee7..bd4e86e 100644
--- a/drivers/net/mlx4/en_rx.c
+++ b/drivers/net/mlx4/en_rx.c
@@ -418,7 +418,7 @@ static int mlx4_en_complete_rx_desc(struct mlx4_en_priv *priv,
break;

/* Save page reference in skb */
- __skb_frag_set_page(&skb_frags_rx[nr], skb_frags[nr].page);
+ __skb_frag_set_page(&skb_frags_rx[nr], skb_frags[nr].page.p); /* XXX */
skb_frags_rx[nr].size = skb_frags[nr].size;
skb_frags_rx[nr].page_offset = skb_frags[nr].page_offset;
dma = be64_to_cpu(rx_desc->data[nr].addr);
diff --git a/drivers/scsi/cxgbi/libcxgbi.c b/drivers/scsi/cxgbi/libcxgbi.c
index 0debb06..43cc6c6 100644
--- a/drivers/scsi/cxgbi/libcxgbi.c
+++ b/drivers/scsi/cxgbi/libcxgbi.c
@@ -1823,7 +1823,7 @@ static int sgl_read_to_frags(struct scatterlist *sg, unsigned int sgoffset,
return -EINVAL;
}

- frags[i].page = page;
+ frags[i].page.p = page;
frags[i].page_offset = sg->offset + sgoffset;
frags[i].size = copy;
i++;
diff --git a/drivers/staging/hv/netvsc_drv.c b/drivers/staging/hv/netvsc_drv.c
index 61989f0..4fc7b3e 100644
--- a/drivers/staging/hv/netvsc_drv.c
+++ b/drivers/staging/hv/netvsc_drv.c
@@ -171,7 +171,7 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
skb_frag_t *f = &skb_shinfo(skb)->frags[i];

- packet->page_buf[i+2].pfn = page_to_pfn(f->page);
+ packet->page_buf[i+2].pfn = page_to_pfn(skb_frag_page(f));
packet->page_buf[i+2].offset = f->page_offset;
packet->page_buf[i+2].len = f->size;
}
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index c015e61..c6a3d4b 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -134,8 +134,17 @@ struct sk_buff;

typedef struct skb_frag_struct skb_frag_t;

+struct skb_frag_destructor {
+ atomic_t ref;
+ int (*destroy)(void *data);
+ void *data;
+};
+
struct skb_frag_struct {
- struct page *page;
+ struct {
+ struct page *p;
+ struct skb_frag_destructor *destructor;
+ } page;
#if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
__u32 page_offset;
__u32 size;
@@ -1128,6 +1137,31 @@ static inline int skb_pagelen(const struct sk_buff *skb)
}

/**
+ * skb_frag_set_destructor - set destructor for a paged fragment
+ * @skb: buffer containing fragment to be initialised
+ * @i: paged fragment index to initialise
+ * @destroy: the destructor to use for this fragment
+ *
+ * Sets @destroy as the destructor to be called when all references to
+ * the frag @i in @skb (tracked over skb_clone, retransmit, pull-ups,
+ * etc) are released.
+ *
+ * When a destructor is set then reference counting is performed on
+ * @destroy->ref. When the ref reaches zero then @destroy->destroy
+ * will be called. The caller is responsible for holding and managing
+ * any other references (such a the struct page reference count).
+ *
+ * This function must be called before any use of skb_frag_ref() or
+ * skb_frag_unref().
+ */
+static inline void skb_frag_set_destructor(struct sk_buff *skb, int i,
+ struct skb_frag_destructor *destroy)
+{
+ skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+ frag->page.destructor = destroy;
+}
+
+/**
* __skb_fill_page_desc - initialise a paged fragment in an skb
* @skb: buffer containing fragment to be initialised
* @i: paged fragment index to initialise
@@ -1145,7 +1179,8 @@ static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
{
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

- frag->page = page;
+ frag->page.p = page;
+ frag->page.destructor = NULL;
frag->page_offset = off;
frag->size = size;
}
@@ -1669,9 +1704,12 @@ static inline void netdev_free_page(struct net_device *dev, struct page *page)
*/
static inline struct page *skb_frag_page(const skb_frag_t *frag)
{
- return frag->page;
+ return frag->page.p;
}

+extern void skb_frag_destructor_ref(struct skb_frag_destructor *destroy);
+extern void skb_frag_destructor_unref(struct skb_frag_destructor *destroy);
+
/**
* __skb_frag_ref - take an addition reference on a paged fragment.
* @frag: the paged fragment
@@ -1680,6 +1718,10 @@ static inline struct page *skb_frag_page(const skb_frag_t *frag)
*/
static inline void __skb_frag_ref(skb_frag_t *frag)
{
+ if (unlikely(frag->page.destructor)) {
+ skb_frag_destructor_ref(frag->page.destructor);
+ return;
+ }
get_page(skb_frag_page(frag));
}

@@ -1703,6 +1745,10 @@ static inline void skb_frag_ref(struct sk_buff *skb, int f)
*/
static inline void __skb_frag_unref(skb_frag_t *frag)
{
+ if (unlikely(frag->page.destructor)) {
+ skb_frag_destructor_unref(frag->page.destructor);
+ return;
+ }
put_page(skb_frag_page(frag));
}

@@ -1755,7 +1801,7 @@ static inline void *skb_frag_address_safe(const skb_frag_t *frag)
*/
static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
{
- frag->page = page;
+ frag->page.p = page;
__skb_frag_ref(frag);
}

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 418f3435..906a3e7 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -292,6 +292,23 @@ struct sk_buff *dev_alloc_skb(unsigned int length)
}
EXPORT_SYMBOL(dev_alloc_skb);

+void skb_frag_destructor_ref(struct skb_frag_destructor *destroy)
+{
+ BUG_ON(destroy == NULL);
+ atomic_inc(&destroy->ref);
+}
+EXPORT_SYMBOL(skb_frag_destructor_ref);
+
+void skb_frag_destructor_unref(struct skb_frag_destructor *destroy)
+{
+ if (destroy == NULL)
+ return;
+
+ if (atomic_dec_and_test(&destroy->ref))
+ destroy->destroy(destroy->data);
+}
+EXPORT_SYMBOL(skb_frag_destructor_unref);
+
static void skb_drop_list(struct sk_buff **listp)
{
struct sk_buff *list = *listp;
@@ -642,14 +659,19 @@ static int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)

/* skb frags release userspace buffers */
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
- put_page(skb_shinfo(skb)->frags[i].page);
+ skb_frag_unref(skb, i);

uarg->callback(uarg);

/* skb frags point to kernel buffers */
for (i = skb_shinfo(skb)->nr_frags; i > 0; i--) {
skb_shinfo(skb)->frags[i - 1].page_offset = 0;
- skb_shinfo(skb)->frags[i - 1].page = head;
+ skb_shinfo(skb)->frags[i - 1].page.p = head;
+ /*
+ * The original destructor is called as necessary when
+ * releasing userspace buffers.
+ */
+ skb_shinfo(skb)->frags[i - 1].page.destructor = NULL;
head = (struct page *)head->private;
}
return 0;
--
1.7.2.5