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author | Willem de Bruijn <willemb@google.com> | 2017-07-31 15:15:47 +0300 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2017-08-02 02:07:10 +0300 |
commit | c613c209c3f351d47158f728271d0c73b6dd24c6 (patch) | |
tree | f048d98774aea477107068c66dde6793dcedaf0b /net/core/skbuff.c | |
parent | 1ae39d658d0269a91baf2b85074a66d6be7a37d9 (diff) | |
download | linux-c613c209c3f351d47158f728271d0c73b6dd24c6.tar.xz |
net: add skb_frag_foreach_page and use with kmap_atomic
Skb frags may contain compound pages. Various operations map frags
temporarily using kmap_atomic, but this function works on single
pages, not whole compound pages. The distinction is only relevant
for high mem pages that require temporary mappings.
Introduce a looping mechanism that for compound highmem pages maps
one page at a time, does not change behavior on other pages.
Use the loop in the kmap_atomic callers in net/core/skbuff.c.
Verified by triggering skb_copy_bits with
tcpdump -n -c 100 -i ${DEV} -w /dev/null &
netperf -t TCP_STREAM -H ${HOST}
and by triggering __skb_checksum with
ethtool -K ${DEV} tx off
repeated the tests with looping on a non-highmem platform
(x86_64) by making skb_frag_must_loop always return true.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/skbuff.c')
-rw-r--r-- | net/core/skbuff.c | 88 |
1 files changed, 59 insertions, 29 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 9c0e015ff3fe..0f0933b338d7 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -938,8 +938,10 @@ int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask) 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]; + u32 p_off, p_len, copied; + struct page *p; + u8 *vaddr; page = alloc_page(gfp_mask); if (!page) { @@ -950,10 +952,15 @@ int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask) } return -ENOMEM; } - vaddr = kmap_atomic(skb_frag_page(f)); - memcpy(page_address(page), - vaddr + f->page_offset, skb_frag_size(f)); - kunmap_atomic(vaddr); + + skb_frag_foreach_page(f, f->page_offset, skb_frag_size(f), + p, p_off, p_len, copied) { + vaddr = kmap_atomic(p); + memcpy(page_address(page) + copied, vaddr + p_off, + p_len); + kunmap_atomic(vaddr); + } + set_page_private(page, (unsigned long)head); head = page; } @@ -1753,16 +1760,20 @@ int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len) end = start + skb_frag_size(f); if ((copy = end - offset) > 0) { + u32 p_off, p_len, copied; + struct page *p; u8 *vaddr; if (copy > len) copy = len; - vaddr = kmap_atomic(skb_frag_page(f)); - memcpy(to, - vaddr + f->page_offset + offset - start, - copy); - kunmap_atomic(vaddr); + skb_frag_foreach_page(f, + f->page_offset + offset - start, + copy, p, p_off, p_len, copied) { + vaddr = kmap_atomic(p); + memcpy(to + copied, vaddr + p_off, p_len); + kunmap_atomic(vaddr); + } if ((len -= copy) == 0) return 0; @@ -2122,15 +2133,20 @@ int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len) end = start + skb_frag_size(frag); if ((copy = end - offset) > 0) { + u32 p_off, p_len, copied; + struct page *p; u8 *vaddr; if (copy > len) copy = len; - vaddr = kmap_atomic(skb_frag_page(frag)); - memcpy(vaddr + frag->page_offset + offset - start, - from, copy); - kunmap_atomic(vaddr); + skb_frag_foreach_page(frag, + frag->page_offset + offset - start, + copy, p, p_off, p_len, copied) { + vaddr = kmap_atomic(p); + memcpy(vaddr + p_off, from + copied, p_len); + kunmap_atomic(vaddr); + } if ((len -= copy) == 0) return 0; @@ -2195,20 +2211,27 @@ __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len, end = start + skb_frag_size(frag); if ((copy = end - offset) > 0) { + u32 p_off, p_len, copied; + struct page *p; __wsum csum2; u8 *vaddr; if (copy > len) copy = len; - vaddr = kmap_atomic(skb_frag_page(frag)); - csum2 = ops->update(vaddr + frag->page_offset + - offset - start, copy, 0); - kunmap_atomic(vaddr); - csum = ops->combine(csum, csum2, pos, copy); + + skb_frag_foreach_page(frag, + frag->page_offset + offset - start, + copy, p, p_off, p_len, copied) { + vaddr = kmap_atomic(p); + csum2 = ops->update(vaddr + p_off, p_len, 0); + kunmap_atomic(vaddr); + csum = ops->combine(csum, csum2, pos, p_len); + pos += p_len; + } + if (!(len -= copy)) return csum; offset += copy; - pos += copy; } start = end; } @@ -2281,24 +2304,31 @@ __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]); if ((copy = end - offset) > 0) { + skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; + u32 p_off, p_len, copied; + struct page *p; __wsum csum2; u8 *vaddr; - skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; if (copy > len) copy = len; - vaddr = kmap_atomic(skb_frag_page(frag)); - csum2 = csum_partial_copy_nocheck(vaddr + - frag->page_offset + - offset - start, to, - copy, 0); - kunmap_atomic(vaddr); - csum = csum_block_add(csum, csum2, pos); + + skb_frag_foreach_page(frag, + frag->page_offset + offset - start, + copy, p, p_off, p_len, copied) { + vaddr = kmap_atomic(p); + csum2 = csum_partial_copy_nocheck(vaddr + p_off, + to + copied, + p_len, 0); + kunmap_atomic(vaddr); + csum = csum_block_add(csum, csum2, pos); + pos += p_len; + } + if (!(len -= copy)) return csum; offset += copy; to += copy; - pos += copy; } start = end; } |