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: 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 c59bbc3277632ca6f258255d6ef6ffd1b1e8bf10..0bd7c9e6c9a0de3c02f97899c05277992a7bbf57 100644 (file)
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -316,6 +316,9 @@ 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;
 }