This is a note to let you know that I've just added the patch titled
batman-adv: Reserve needed_*room for fragments
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summ...
The filename of the patch is: batman-adv-reserve-needed_-room-for-fragments.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Tue Nov 23 01:39:02 PM CET 2021 From: Sven Eckelmann sven@narfation.org Date: Sat, 20 Nov 2021 13:39:37 +0100 Subject: batman-adv: Reserve needed_*room for fragments To: stable@vger.kernel.org Cc: b.a.t.m.a.n@lists.open-mesh.org, Sven Eckelmann sven@narfation.org, Simon Wunderlich sw@simonwunderlich.de Message-ID: 20211120123939.260723-10-sven@narfation.org
From: Sven Eckelmann sven@narfation.org
commit c5cbfc87558168ef4c3c27ce36eba6b83391db19 upstream.
The batadv net_device is trying to propagate the needed_headroom and needed_tailroom from the lower devices. This is needed to avoid cost intensive reallocations using pskb_expand_head during the transmission.
But the fragmentation code split the skb's without adding extra room at the end/beginning of the various fragments. This reduced the performance of transmissions over complex scenarios (batadv on vxlan on wireguard) because the lower devices had to perform the reallocations at least once.
Fixes: ee75ed88879a ("batman-adv: Fragment and send skbs larger than mtu") Signed-off-by: Sven Eckelmann sven@narfation.org Signed-off-by: Simon Wunderlich sw@simonwunderlich.de [ bp: 4.4 backported: adjust context. ] Signed-off-by: Sven Eckelmann sven@narfation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/batman-adv/fragmentation.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)
--- a/net/batman-adv/fragmentation.c +++ b/net/batman-adv/fragmentation.c @@ -394,6 +394,7 @@ out:
/** * batadv_frag_create - create a fragment from skb + * @net_dev: outgoing device for fragment * @skb: skb to create fragment from * @frag_head: header to use in new fragment * @fragment_size: size of new fragment @@ -404,22 +405,25 @@ out: * * Returns the new fragment, NULL on error. */ -static struct sk_buff *batadv_frag_create(struct sk_buff *skb, +static struct sk_buff *batadv_frag_create(struct net_device *net_dev, + struct sk_buff *skb, struct batadv_frag_packet *frag_head, unsigned int fragment_size) { + unsigned int ll_reserved = LL_RESERVED_SPACE(net_dev); + unsigned int tailroom = net_dev->needed_tailroom; struct sk_buff *skb_fragment; unsigned header_size = sizeof(*frag_head); unsigned mtu = fragment_size + header_size;
- skb_fragment = netdev_alloc_skb(NULL, mtu + ETH_HLEN); + skb_fragment = dev_alloc_skb(ll_reserved + mtu + tailroom); if (!skb_fragment) goto err;
skb->priority = TC_PRIO_CONTROL;
/* Eat the last mtu-bytes of the skb */ - skb_reserve(skb_fragment, header_size + ETH_HLEN); + skb_reserve(skb_fragment, ll_reserved + header_size); skb_split(skb, skb_fragment, skb->len - fragment_size);
/* Add the header */ @@ -442,11 +446,12 @@ bool batadv_frag_send_packet(struct sk_b struct batadv_orig_node *orig_node, struct batadv_neigh_node *neigh_node) { + struct net_device *net_dev = neigh_node->if_incoming->net_dev; struct batadv_priv *bat_priv; struct batadv_hard_iface *primary_if = NULL; struct batadv_frag_packet frag_header; struct sk_buff *skb_fragment; - unsigned mtu = neigh_node->if_incoming->net_dev->mtu; + unsigned mtu = net_dev->mtu; unsigned header_size = sizeof(frag_header); unsigned max_fragment_size, num_fragments; bool ret = false; @@ -489,7 +494,7 @@ bool batadv_frag_send_packet(struct sk_b if (frag_header.no == BATADV_FRAG_MAX_FRAGMENTS - 1) goto out_err;
- skb_fragment = batadv_frag_create(skb, &frag_header, + skb_fragment = batadv_frag_create(net_dev, skb, &frag_header, max_fragment_size); if (!skb_fragment) goto out_err;
Patches currently in stable-queue which might be from sven@narfation.org are
queue-4.4/batman-adv-consider-fragmentation-for-needed_headroom.patch queue-4.4/ath9k-fix-potential-interrupt-storm-on-queue-reset.patch queue-4.4/batman-adv-set-.owner-to-this_module.patch queue-4.4/batman-adv-mcast-fix-duplicate-mcast-packets-from-bla-backbone-to-mesh.patch queue-4.4/batman-adv-fix-multicast-tt-issues-with-bogus-roam-flags.patch queue-4.4/batman-adv-mcast-fix-duplicate-mcast-packets-in-bla-backbone-from-lan.patch queue-4.4/batman-adv-reserve-needed_-room-for-fragments.patch queue-4.4/net-batman-adv-fix-error-handling.patch queue-4.4/batman-adv-keep-fragments-equally-sized.patch queue-4.4/batman-adv-avoid-warn_on-timing-related-checks.patch queue-4.4/batman-adv-prevent-duplicated-softif_vlan-entry.patch queue-4.4/batman-adv-don-t-always-reallocate-the-fragmentation-skb-head.patch queue-4.4/batman-adv-mcast-fix-duplicate-mcast-packets-in-bla-backbone-from-mesh.patch