tree 3efc2cf6c22380a6ae65547d79732efcf98b048f
parent 88d145ee3b15989ccd973348371ed2b791b2c6e7
author Sven Eckelmann <sven@narfation.org> 1637411998 +0100
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1637923723 +0100

batman-adv: Don't always reallocate the fragmentation skb head

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>
[ bp: 4.9 backported: adjust context. ]
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>