On Sun, 2008-05-04 at 10:47 +0200, Johannes Berg wrote: > On Sun, 2008-05-04 at 11:16 +0800, Herbert Xu wrote: > > On Sun, May 04, 2008 at 04:22:20AM +0200, Johannes Berg wrote: > > > > > > Yes, wireless always needs at least 24 bytes, but more likely 34 > > > (encryption+QoS). However, I just increased LL_MAX_HEADER to 54 and that > > > doesn't seem to have helped. > > > > How did you test it? > > I stuck a WARN_ON((nhead || ntail) && skb->sk) into pskb_expand_head > (which never triggered except from mac80211). And mac80211 has code that > calculates the required header length and only calls pskb_expand_head() > from that place when it needs more header space (or the skb is cloned. I > should repeat this test) I just re-did the test, and I definitely need 29 more bytes on, for example, the IPv6 autodiscovery packets and ICMP packets generated with ping(8). Some of them even need additional tailroom. johannes
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