On Tue, 2010-05-11 at 11:52 -0700, Abhijeet Kolekar wrote: > Hello John, > On Tue, 2010-05-11 at 11:24 -0700, John W. Linville wrote: > > On Tue, May 11, 2010 at 11:16:50AM -0700, Abhijeet Kolekar wrote: > > > Hello John, > > > On Tue, 2010-05-11 at 11:14 -0700, John W. Linville wrote: > > > > On Tue, May 11, 2010 at 11:22:11AM -0700, Abhijeet Kolekar wrote: > > > > > Paged RX skb patch broke the defragmentation. We need to read hdr again > > > > > after linearization. > > > > > > > > > > It fixes following bug > > > > > http://bugzilla.intellinuxwireless.org/show_bug.cgi?id=2194 > > > > > > > > > > Signed-off-by: Zhu, Yi <yi.zhu@xxxxxxxxx> > > > > > Signed-off-by: Abhijeet Kolekar <abhijeet.kolekar@xxxxxxxxx> > > > > > --- > > > > > v2: Changed hdr reading. > > > > > v3: Added more comments. > > > > > net/mac80211/rx.c | 6 ++++++ > > > > > 1 files changed, 6 insertions(+), 0 deletions(-) > > > > > > > > > > diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c > > > > > index 9a08f2c..6e2a7bc 100644 > > > > > --- a/net/mac80211/rx.c > > > > > +++ b/net/mac80211/rx.c > > > > > @@ -1253,6 +1253,12 @@ ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx) > > > > > if (skb_linearize(rx->skb)) > > > > > return RX_DROP_UNUSABLE; > > > > > > > > > > + /* > > > > > + * skb_linearize() might change the skb->data and > > > > > + * previously cached variables (in this case, hdr) need to > > > > > + * be refreshed with the new data. > > > > > + */ > > > > > + hdr = (struct ieee80211_hdr *)rx->skb->data; > > > > > seq = (sc & IEEE80211_SCTL_SEQ) >> 4; > > > > > > > > > > if (frag == 0) { > > > > > > > > And what about making sure the compiler doesn't optimize this away? > > > > > > > To avoid the double assignment, there is one more approach is to > > > directly read fc and seq_ctrl using skb_data. I will send that in the > > > next version. > > > > I don't think the double assignment is so bad, I just think that a > > compiler might decide to ignore the second assignment. Am I wrong? > > > I don't understand why compiler will ignore the second assignment other > than the above reason. What will be the solution in this case? ACCESS_ONCE()? I have no idea why/if the compiler would actually do this though. johannes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
