hollalinux
/
linux-sg2042
mirror of https://github.com/sophgo/linux-riscv.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

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>
This commit is contained in:
Willem de Bruijn 2017-07-31 08:15:47 -04:00 committed by David S. Miller
parent 1ae39d658d
commit c613c209c3
2 changed files with 95 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
include/linux/skbuff.h
View File

@ -345,6 +345,42 @@ static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
frag->size -= delta;
}
static inline bool skb_frag_must_loop(struct page *p)
{
#if defined(CONFIG_HIGHMEM)
if (PageHighMem(p))
return true;
#endif
return false;
}
/**
* skb_frag_foreach_page - loop over pages in a fragment
*
* @f: skb frag to operate on
* @f_off: offset from start of f->page.p
* @f_len: length from f_off to loop over
* @p: (temp var) current page
* @p_off: (temp var) offset from start of current page,
* non-zero only on first page.
* @p_len: (temp var) length in current page,
* < PAGE_SIZE only on first and last page.
* @copied: (temp var) length so far, excluding current p_len.
*
* A fragment can hold a compound page, in which case per-page
* operations, notably kmap_atomic, must be called for each
* regular page.
*/
#define skb_frag_foreach_page(f, f_off, f_len, p, p_off, p_len, copied) \
for (p = skb_frag_page(f) + ((f_off) >> PAGE_SHIFT), \
p_off = (f_off) & (PAGE_SIZE - 1), \
p_len = skb_frag_must_loop(p) ? \
min_t(u32, f_len, PAGE_SIZE - p_off) : f_len, \
copied = 0; \
copied < f_len; \
copied += p_len, p++, p_off = 0, \
p_len = min_t(u32, f_len - copied, PAGE_SIZE)) \
#define HAVE_HW_TIME_STAMP
/**

88
net/core/skbuff.c
View File

@ -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;
}