rt2x00: do not align payload on modern H/W
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 <alankila@bel.fi> Debugged-by: Antti S. Lankila <alankila@bel.fi> Reported-by: Henrik Asp <solenskiner@gmail.com> Originally-From: Helmut Schaa <helmut.schaa@googlemail.com> Cc: stable@vger.kernel.org Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
parent
9d828ad7d3
commit
cfd9167af1
|
@ -158,55 +158,29 @@ void rt2x00queue_align_frame(struct sk_buff *skb)
|
|||
skb_trim(skb, frame_length);
|
||||
}
|
||||
|
||||
void rt2x00queue_insert_l2pad(struct sk_buff *skb, unsigned int header_length)
|
||||
/*
|
||||
* H/W needs L2 padding between the header and the paylod if header size
|
||||
* is not 4 bytes aligned.
|
||||
*/
|
||||
void rt2x00queue_insert_l2pad(struct sk_buff *skb, unsigned int hdr_len)
|
||||
{
|
||||
unsigned int payload_length = skb->len - header_length;
|
||||
unsigned int header_align = ALIGN_SIZE(skb, 0);
|
||||
unsigned int payload_align = ALIGN_SIZE(skb, header_length);
|
||||
unsigned int l2pad = payload_length ? L2PAD_SIZE(header_length) : 0;
|
||||
|
||||
/*
|
||||
* Adjust the header alignment if the payload needs to be moved more
|
||||
* than the header.
|
||||
*/
|
||||
if (payload_align > header_align)
|
||||
header_align += 4;
|
||||
|
||||
/* There is nothing to do if no alignment is needed */
|
||||
if (!header_align)
|
||||
return;
|
||||
|
||||
/* Reserve the amount of space needed in front of the frame */
|
||||
skb_push(skb, header_align);
|
||||
|
||||
/*
|
||||
* Move the header.
|
||||
*/
|
||||
memmove(skb->data, skb->data + header_align, header_length);
|
||||
|
||||
/* Move the payload, if present and if required */
|
||||
if (payload_length && payload_align)
|
||||
memmove(skb->data + header_length + l2pad,
|
||||
skb->data + header_length + l2pad + payload_align,
|
||||
payload_length);
|
||||
|
||||
/* Trim the skb to the correct size */
|
||||
skb_trim(skb, header_length + l2pad + payload_length);
|
||||
}
|
||||
|
||||
void rt2x00queue_remove_l2pad(struct sk_buff *skb, unsigned int header_length)
|
||||
{
|
||||
/*
|
||||
* L2 padding is only present if the skb contains more than just the
|
||||
* IEEE 802.11 header.
|
||||
*/
|
||||
unsigned int l2pad = (skb->len > header_length) ?
|
||||
L2PAD_SIZE(header_length) : 0;
|
||||
unsigned int l2pad = (skb->len > hdr_len) ? L2PAD_SIZE(hdr_len) : 0;
|
||||
|
||||
if (!l2pad)
|
||||
return;
|
||||
|
||||
memmove(skb->data + l2pad, skb->data, header_length);
|
||||
skb_push(skb, l2pad);
|
||||
memmove(skb->data, skb->data + l2pad, hdr_len);
|
||||
}
|
||||
|
||||
void rt2x00queue_remove_l2pad(struct sk_buff *skb, unsigned int hdr_len)
|
||||
{
|
||||
unsigned int l2pad = (skb->len > hdr_len) ? L2PAD_SIZE(hdr_len) : 0;
|
||||
|
||||
if (!l2pad)
|
||||
return;
|
||||
|
||||
memmove(skb->data + l2pad, skb->data, hdr_len);
|
||||
skb_pull(skb, l2pad);
|
||||
}
|
||||
|
||||
|
|
Loading…
Reference in a new issue