Namely, have off counted starting from 0 rather than from csstate->off.
To compensate we need to shift the initial value (csstate->sum) (rotate
by 8 bits, as usual for csum) and do the same after we are finished adding
the pieces up.
What we get out of that is a bit more redundancy in our variables - from
is always equal to addr + off, which will be useful several commits down
the road.
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
include/net/checksum.h | 14 ++++++++------
lib/iov_iter.c | 8 ++++----
2 files changed, 12 insertions(+), 10 deletions(-)
diff --git a/include/net/checksum.h b/include/net/checksum.h
index 0d05b9e8690b..5b96d5bd6e54 100644
--- a/include/net/checksum.h
+++ b/include/net/checksum.h
@@ -80,16 +80,18 @@ static inline __sum16 csum16_sub(__sum16 csum, __be16 addend)
return csum16_add(csum, ~addend);
}
-static inline __wsum
-csum_block_add(__wsum csum, __wsum csum2, int offset)
+static inline __wsum csum_shift(__wsum sum, int offset)
{
- u32 sum = (__force u32)csum2;
-
/* rotate sum to align it with a 16b boundary */
if (offset & 1)
- sum = ror32(sum, 8);
+ return (__force __wsum)ror32((__force u32)sum, 8);
+ return sum;
+}
- return csum_add(csum, (__force __wsum)sum);
+static inline __wsum
+csum_block_add(__wsum csum, __wsum csum2, int offset)
+{
+ return csum_add(csum, csum_shift(csum2, offset));
}
static inline __wsum
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index dbd6b92f6200..906e9d49c487 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1794,8 +1794,8 @@ size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate,
if (unlikely(iov_iter_is_pipe(i)))
return csum_and_copy_to_pipe_iter(addr, bytes, _csstate, i);
- sum = csstate->csum;
- off = csstate->off;
+ sum = csum_shift(csstate->csum, csstate->off);
+ off = 0;
if (unlikely(iov_iter_is_discard(i))) {
WARN_ON(1); /* for now */
return 0;
@@ -1830,8 +1830,8 @@ size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate,
off += v.bv_len;
})
)
- csstate->csum = sum;
- csstate->off = off;
+ csstate->csum = csum_shift(sum, csstate->off);
+ csstate->off += bytes;
return bytes;
}
EXPORT_SYMBOL(csum_and_copy_to_iter);
--
2.11.0
