On 04/23/2015 12:30 PM, Cong Wang wrote:
(Off-topic...)
On Wed, Apr 22, 2015 at 4:23 PM, Cong Wang <cw...@twopensource.com> wrote:
The code looks correct to me now, except it is suspicious skb->len
is not updated after skb_copy_to_linear_data() while skb->tail is
advanced already. I need to think more before submitting a patch.
I feel like we need the following patch, maybe skb->len is updated somewhere
else by "skb->tail - skb->head", otherwise we are screwed?
Maybe in skb_add_rx_frag? You might take a look at it.
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c
b/drivers/net/ethernet/intel/igb/igb_main.c
index a0a9b1f..66e6fb6 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -6843,7 +6843,6 @@ static void igb_pull_tail(struct igb_ring *rx_ring,
skb_frag_size_sub(frag, IGB_TS_HDR_LEN);
frag->page_offset += IGB_TS_HDR_LEN;
skb->data_len -= IGB_TS_HDR_LEN;
- skb->len -= IGB_TS_HDR_LEN;
/* move va to start of packet data */
va += IGB_TS_HDR_LEN;
@@ -6856,12 +6855,12 @@ static void igb_pull_tail(struct igb_ring *rx_ring,
/* align pull length to size of long to optimize memcpy performance */
skb_copy_to_linear_data(skb, va, ALIGN(pull_len, sizeof(long)));
+ __skb_put(skb, pull_len);
/* update all of the pointers */
skb_frag_size_sub(frag, pull_len);
frag->page_offset += pull_len;
skb->data_len -= pull_len;
- skb->tail += pull_len;
}
/**
Seriously? Are you even reading the code? The fragment is already a
part of the skb, as such it is already included in skb->len. By
re-adding the header you are adding bytes that aren't there. All we
were doing is moving data from a fragment to the linear portion.
No offense but your starting to waste my time with these silly patch
ideas. The patches I submitted to intel-wired-lan fix the issue that
you found, and there aren't any new issues that it creates so the issue
is resolved. And like I said if you need to fix this in stable just
subtract IGB_TS_HDR_LEN from the header length scanned in
eth_get_headlen and it will resolve the issue you reported and that way
we can fix the issue and avoid pulling a fragment down to size 0.
- Alex
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