Merge branch 'bpf-csum-complete'

Daniel Borkmann says:

====================
Few BPF helper related checksum fixes

The set contains three fixes with regards to CHECKSUM_COMPLETE
and BPF helper functions. For details please see individual
patches.

Thanks!

v1 -> v2:
  - Fixed make htmldocs issue reported by kbuild bot.
  - Rest as is.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 33 insertions, 19 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6f0b3e0adc73..0f665cb26b50 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2847,6 +2847,18 @@ static inline int skb_linearize_cow(struct sk_buff *skb)
 	       __skb_linearize(skb) : 0;
 }
 
+static __always_inline void
+__skb_postpull_rcsum(struct sk_buff *skb, const void *start, unsigned int len,
+		     unsigned int off)
+{
+	if (skb->ip_summed == CHECKSUM_COMPLETE)
+		skb->csum = csum_block_sub(skb->csum,
+					   csum_partial(start, len, 0), off);
+	else if (skb->ip_summed == CHECKSUM_PARTIAL &&
+		 skb_checksum_start_offset(skb) < 0)
+		skb->ip_summed = CHECKSUM_NONE;
+}
+
 /**
  *	skb_postpull_rcsum - update checksum for received skb after pull
  *	@skb: buffer to update
@@ -2857,36 +2869,38 @@ static inline int skb_linearize_cow(struct sk_buff *skb)
  *	update the CHECKSUM_COMPLETE checksum, or set ip_summed to
  *	CHECKSUM_NONE so that it can be recomputed from scratch.
  */
-
 static inline void skb_postpull_rcsum(struct sk_buff *skb,
 				      const void *start, unsigned int len)
 {
-	if (skb->ip_summed == CHECKSUM_COMPLETE)
-		skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
-	else if (skb->ip_summed == CHECKSUM_PARTIAL &&
-		 skb_checksum_start_offset(skb) < 0)
-		skb->ip_summed = CHECKSUM_NONE;
+	__skb_postpull_rcsum(skb, start, len, 0);
 }
 
-unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
+static __always_inline void
+__skb_postpush_rcsum(struct sk_buff *skb, const void *start, unsigned int len,
+		     unsigned int off)
+{
+	if (skb->ip_summed == CHECKSUM_COMPLETE)
+		skb->csum = csum_block_add(skb->csum,
+					   csum_partial(start, len, 0), off);
+}
 
+/**
+ *	skb_postpush_rcsum - update checksum for received skb after push
+ *	@skb: buffer to update
+ *	@start: start of data after push
+ *	@len: length of data pushed
+ *
+ *	After doing a push on a received packet, you need to call this to
+ *	update the CHECKSUM_COMPLETE checksum.
+ */
 static inline void skb_postpush_rcsum(struct sk_buff *skb,
 				      const void *start, unsigned int len)
 {
-	/* For performing the reverse operation to skb_postpull_rcsum(),
-	 * we can instead of ...
-	 *
-	 *   skb->csum = csum_add(skb->csum, csum_partial(start, len, 0));
-	 *
-	 * ... just use this equivalent version here to save a few
-	 * instructions. Feeding csum of 0 in csum_partial() and later
-	 * on adding skb->csum is equivalent to feed skb->csum in the
-	 * first place.
-	 */
-	if (skb->ip_summed == CHECKSUM_COMPLETE)
-		skb->csum = csum_partial(start, len, skb->csum);
+	__skb_postpush_rcsum(skb, start, len, 0);
 }
 
+unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
+
 /**
  *	skb_push_rcsum - push skb and update receive checksum
  *	@skb: buffer to update