Callers of skb_seq_read() are currently forced to call skb_abort_seq_read()
even when consuming all the data because the last call to skb_seq_read (the
one that returns 0 to indicate the end) fails to unmap the last fragment page.

With this patch callers will be allowed to traverse the SKB data by calling
skb_prepare_seq_read() once and repeatedly calling skb_seq_read() as originally
intended (and documented in the original commit 677e90eda), that is, only call
skb_abort_seq_read() if the sequential read is actually aborted.

Signed-off-by: Wedson Almeida Filho <wedso...@gmail.com>
---
 net/core/skbuff.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index cfd777b..26ea1cf 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2554,8 +2554,13 @@ unsigned int skb_seq_read(unsigned int consumed, const 
u8 **data,
        unsigned int block_limit, abs_offset = consumed + st->lower_offset;
        skb_frag_t *frag;
 
-       if (unlikely(abs_offset >= st->upper_offset))
+       if (unlikely(abs_offset >= st->upper_offset)) {
+               if (st->frag_data) {
+                       kunmap_atomic(st->frag_data);
+                       st->frag_data = NULL;
+               }
                return 0;
+       }
 
 next_skb:
        block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
-- 
1.7.9.5

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