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-rw-r--r--include/linux/skbuff.h16
-rw-r--r--net/core/skbuff.c80
2 files changed, 95 insertions, 1 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 3e543371254..08d4507715f 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -187,6 +187,20 @@ enum {
/* ensure the originating sk reference is available on driver level */
SKBTX_DRV_NEEDS_SK_REF = 1 << 3,
+
+ /* device driver supports TX zero-copy buffers */
+ SKBTX_DEV_ZEROCOPY = 1 << 4,
+};
+
+/*
+ * The callback notifies userspace to release buffers when skb DMA is done in
+ * lower device, the skb last reference should be 0 when calling this.
+ * The desc is used to track userspace buffer index.
+ */
+struct ubuf_info {
+ void (*callback)(void *);
+ void *arg;
+ unsigned long desc;
};
/* This data is invariant across clones and lives at
@@ -211,6 +225,7 @@ struct skb_shared_info {
/* Intermediate layers must ensure that destructor_arg
* remains valid until skb destructor */
void * destructor_arg;
+
/* must be last field, see pskb_expand_head() */
skb_frag_t frags[MAX_SKB_FRAGS];
};
@@ -2265,5 +2280,6 @@ static inline void skb_checksum_none_assert(struct sk_buff *skb)
}
bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
+
#endif /* __KERNEL__ */
#endif /* _LINUX_SKBUFF_H */
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 46cbd28f40f..a9577a2f3a4 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -329,6 +329,18 @@ static void skb_release_data(struct sk_buff *skb)
put_page(skb_shinfo(skb)->frags[i].page);
}
+ /*
+ * If skb buf is from userspace, we need to notify the caller
+ * the lower device DMA has done;
+ */
+ if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
+ struct ubuf_info *uarg;
+
+ uarg = skb_shinfo(skb)->destructor_arg;
+ if (uarg->callback)
+ uarg->callback(uarg);
+ }
+
if (skb_has_frag_list(skb))
skb_drop_fraglist(skb);
@@ -481,6 +493,9 @@ bool skb_recycle_check(struct sk_buff *skb, int skb_size)
if (irqs_disabled())
return false;
+ if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)
+ return false;
+
if (skb_is_nonlinear(skb) || skb->fclone != SKB_FCLONE_UNAVAILABLE)
return false;
@@ -596,6 +611,51 @@ struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
}
EXPORT_SYMBOL_GPL(skb_morph);
+/* skb frags copy userspace buffers to kernel */
+static int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
+{
+ int i;
+ int num_frags = skb_shinfo(skb)->nr_frags;
+ struct page *page, *head = NULL;
+ struct ubuf_info *uarg = skb_shinfo(skb)->destructor_arg;
+
+ for (i = 0; i < num_frags; i++) {
+ u8 *vaddr;
+ skb_frag_t *f = &skb_shinfo(skb)->frags[i];
+
+ page = alloc_page(GFP_ATOMIC);
+ if (!page) {
+ while (head) {
+ struct page *next = (struct page *)head->private;
+ put_page(head);
+ head = next;
+ }
+ return -ENOMEM;
+ }
+ vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
+ memcpy(page_address(page),
+ vaddr + f->page_offset, f->size);
+ kunmap_skb_frag(vaddr);
+ page->private = (unsigned long)head;
+ head = page;
+ }
+
+ /* skb frags release userspace buffers */
+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+ put_page(skb_shinfo(skb)->frags[i].page);
+
+ 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;
+ head = (struct page *)head->private;
+ }
+ return 0;
+}
+
+
/**
* skb_clone - duplicate an sk_buff
* @skb: buffer to clone
@@ -614,6 +674,11 @@ struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
{
struct sk_buff *n;
+ if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
+ if (skb_copy_ubufs(skb, gfp_mask))
+ return NULL;
+ }
+
n = skb + 1;
if (skb->fclone == SKB_FCLONE_ORIG &&
n->fclone == SKB_FCLONE_UNAVAILABLE) {
@@ -731,6 +796,12 @@ struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
if (skb_shinfo(skb)->nr_frags) {
int i;
+ if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
+ if (skb_copy_ubufs(skb, gfp_mask)) {
+ kfree(n);
+ goto out;
+ }
+ }
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
get_page(skb_shinfo(n)->frags[i].page);
@@ -788,7 +859,6 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
fastpath = true;
else {
int delta = skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1;
-
fastpath = atomic_read(&skb_shinfo(skb)->dataref) == delta;
}
@@ -819,6 +889,11 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
if (fastpath) {
kfree(skb->head);
} else {
+ /* copy this zero copy skb frags */
+ if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
+ if (skb_copy_ubufs(skb, gfp_mask))
+ goto nofrags;
+ }
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
get_page(skb_shinfo(skb)->frags[i].page);
@@ -853,6 +928,8 @@ adjust_others:
atomic_set(&skb_shinfo(skb)->dataref, 1);
return 0;
+nofrags:
+ kfree(data);
nodata:
return -ENOMEM;
}
@@ -1354,6 +1431,7 @@ int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
}
start = end;
}
+
if (!len)
return 0;