batman-adv: Consider fragmentation for needed_headroom

[ Upstream commit 4ca23e2c2074465bff55ea14221175fecdf63c5f ]

If a batman-adv packets has to be fragmented, then the original batman-adv
packet header is not stripped away. Instead, only a new header is added in
front of the packet after it was split.

This size must be considered to avoid cost intensive reallocations during
the transmission through the various device layers.

Fixes: 7bca68c7844b ("batman-adv: Add lower layer needed_(head|tail)room to own ones")
Reported-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index fa06b51c0144da72ab5debbd997472c5b1e79ee0..d72c183919b441cb902c4b1524f45cf5030cb2a0 100644 (file)
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -554,6 +554,9 @@ static void batadv_hardif_recalc_extra_skbroom(struct net_device *soft_iface)
        needed_headroom = lower_headroom + (lower_header_len - ETH_HLEN);
        needed_headroom += batadv_max_header_len();
 
+       /* fragmentation headers don't strip the unicast/... header */
+       needed_headroom += sizeof(struct batadv_frag_packet);
+
        soft_iface->needed_headroom = needed_headroom;
        soft_iface->needed_tailroom = lower_tailroom;
 }