From: Stanislaw Gruszka Date: Tue, 11 Nov 2014 13:28:47 +0000 (+0100) Subject: rt2x00: do not align payload on modern H/W X-Git-Tag: v3.2.65~41 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f8ddde5a235cda17012fddd84c0d49d8d8325a16;p=pandora-kernel.git rt2x00: do not align payload on modern H/W commit cfd9167af14eb4ec21517a32911d460083ee3d59 upstream. RT2800 and newer hardware require padding between header and payload if header length is not multiple of 4. For historical reasons we also align payload to to 4 bytes boundary, but such alignment is not needed on modern H/W. Patch fixes skb_under_panic problems reported from time to time: https://bugzilla.kernel.org/show_bug.cgi?id=84911 https://bugzilla.kernel.org/show_bug.cgi?id=72471 http://marc.info/?l=linux-wireless&m=139108549530402&w=2 https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1087591 Panic happened because we eat 4 bytes of skb headroom on each (re)transmission when sending frame without the payload and the header length not being multiple of 4 (i.e. QoS header has 26 bytes). On such case because paylad_aling=2 is bigger than header_align=0 we increase header_align by 4 bytes. To prevent that we could change the check to: if (payload_length && payload_align > header_align) header_align += 4; but not aligning payload at all is more effective and alignment is not really needed by H/W (that has been tested on OpenWrt project for few years now). Reported-and-tested-by: Antti S. Lankila Debugged-by: Antti S. Lankila Reported-by: Henrik Asp Originally-From: Helmut Schaa Signed-off-by: Stanislaw Gruszka Signed-off-by: John W. Linville Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed