This is a note to let you know that I've just added the patch titled
batman-adv: Don't always reallocate the fragmentation skb head
to the 4.19-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-don-t-always-reallocate-the-fragmentation-skb-head.patch and it can be found in the queue-4.19 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 01:33:57 PM CET 2021 From: Sven Eckelmann sven@narfation.org Date: Sat, 20 Nov 2021 13:40:44 +0100 Subject: batman-adv: Don't always reallocate the fragmentation skb head 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: 20211120124044.261086-5-sven@narfation.org
From: Sven Eckelmann sven@narfation.org
commit 992b03b88e36254e26e9a4977ab948683e21bd9f upstream.
When a packet is fragmented by batman-adv, the original batman-adv header is not modified. Only a new fragmentation is inserted between the original one and the ethernet header. The code must therefore make sure that it has a writable region of this size in the skbuff head.
But it is not useful to always reallocate the skbuff by this size even when there would be more than enough headroom still in the skb. The reallocation is just to costly during in this codepath.
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 Signed-off-by: Sven Eckelmann sven@narfation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/batman-adv/fragmentation.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
--- a/net/batman-adv/fragmentation.c +++ b/net/batman-adv/fragmentation.c @@ -539,13 +539,14 @@ int batadv_frag_send_packet(struct sk_bu frag_header.no++; }
- /* Make room for the fragment header. */ - if (batadv_skb_head_push(skb, header_size) < 0 || - pskb_expand_head(skb, header_size + ETH_HLEN, 0, GFP_ATOMIC) < 0) { - ret = -ENOMEM; + /* make sure that there is at least enough head for the fragmentation + * and ethernet headers + */ + ret = skb_cow_head(skb, ETH_HLEN + header_size); + if (ret < 0) goto put_primary_if; - }
+ skb_push(skb, header_size); memcpy(skb->data, &frag_header, header_size);
/* Send the last fragment */
Patches currently in stable-queue which might be from sven@narfation.org are
queue-4.19/batman-adv-consider-fragmentation-for-needed_headroom.patch queue-4.19/ath9k-fix-potential-interrupt-storm-on-queue-reset.patch queue-4.19/ath10k-fix-max-antenna-gain-unit.patch queue-4.19/batman-adv-mcast-fix-duplicate-mcast-packets-in-bla-backbone-from-lan.patch queue-4.19/batman-adv-reserve-needed_-room-for-fragments.patch queue-4.19/batman-adv-don-t-always-reallocate-the-fragmentation-skb-head.patch