diff options
Diffstat (limited to 'package/kernel/mac80211/patches/308-rt2x00-do-not-align-payload-on-modern-H-W.patch')
| -rw-r--r-- | package/kernel/mac80211/patches/308-rt2x00-do-not-align-payload-on-modern-H-W.patch | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/package/kernel/mac80211/patches/308-rt2x00-do-not-align-payload-on-modern-H-W.patch b/package/kernel/mac80211/patches/308-rt2x00-do-not-align-payload-on-modern-H-W.patch new file mode 100644 index 0000000000..384a0be808 --- /dev/null +++ b/package/kernel/mac80211/patches/308-rt2x00-do-not-align-payload-on-modern-H-W.patch @@ -0,0 +1,95 @@ +From: Stanislaw Gruszka <sgruszka@redhat.com> +Date: Sun, 2 Nov 2014 13:38:47 +0100 +Subject: [PATCH] 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 improve performance on embedded CPUs and _possibly_ 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 + +But we can not explain or otherwise confirm the patch fixes this panic +issue for sure. + +Originally-From: Helmut Schaa <helmut.schaa@googlemail.com> +Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> +--- + +--- a/drivers/net/wireless/rt2x00/rt2x00queue.c ++++ b/drivers/net/wireless/rt2x00/rt2x00queue.c +@@ -158,55 +158,29 @@ void rt2x00queue_align_frame(struct sk_b + 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; ++ unsigned int l2pad = (skb->len > hdr_len) ? L2PAD_SIZE(hdr_len) : 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) ++ if (!l2pad) + 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); ++ skb_push(skb, l2pad); ++ memmove(skb->data, skb->data + l2pad, hdr_len); + } + +-void rt2x00queue_remove_l2pad(struct sk_buff *skb, unsigned int header_length) ++void rt2x00queue_remove_l2pad(struct sk_buff *skb, unsigned int hdr_len) + { +- /* +- * 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); ++ memmove(skb->data + l2pad, skb->data, hdr_len); + skb_pull(skb, l2pad); + } + |