diff options
| -rw-r--r-- | include/linux/skbuff.h | 16 | ||||
| -rw-r--r-- | net/core/skbuff.c | 80 |
2 files changed, 95 insertions, 1 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 3e54337..08d4507 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 46cbd28..a9577a2 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; |