batman-adv: Consider fragmentation for needed_headroom

commit 4ca23e2c2074465bff55ea14221175fecdf63c5f upstream.

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: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index f528761674df9f4b84fd29aebfef80a62097268e..4f384abb4cedd78c557b4f67bb2abb68c815b190 100644 (file)
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -359,6 +359,9 @@ 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;
 }