net: Allow netdevices to specify needed head/tailroom
This patch adds needed_headroom/needed_tailroom members to struct
net_device and updates many places that allocate sbks to use them. Not
all of them can be converted though, and I'm sure I missed some (I
mostly grepped for LL_RESERVED_SPACE)
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index a3fb57f..b11e6e1 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -246,11 +246,16 @@
*
* We could use other alignment values, but we must maintain the
* relationship HH alignment <= LL alignment.
+ *
+ * LL_ALLOCATED_SPACE also takes into account the tailroom the device
+ * may need.
*/
#define LL_RESERVED_SPACE(dev) \
- (((dev)->hard_header_len&~(HH_DATA_MOD - 1)) + HH_DATA_MOD)
+ ((((dev)->hard_header_len+(dev)->needed_headroom)&~(HH_DATA_MOD - 1)) + HH_DATA_MOD)
#define LL_RESERVED_SPACE_EXTRA(dev,extra) \
- ((((dev)->hard_header_len+extra)&~(HH_DATA_MOD - 1)) + HH_DATA_MOD)
+ ((((dev)->hard_header_len+(dev)->needed_headroom+(extra))&~(HH_DATA_MOD - 1)) + HH_DATA_MOD)
+#define LL_ALLOCATED_SPACE(dev) \
+ ((((dev)->hard_header_len+(dev)->needed_headroom+(dev)->needed_tailroom)&~(HH_DATA_MOD - 1)) + HH_DATA_MOD)
struct header_ops {
int (*create) (struct sk_buff *skb, struct net_device *dev,
@@ -569,6 +574,13 @@
unsigned short type; /* interface hardware type */
unsigned short hard_header_len; /* hardware hdr length */
+ /* extra head- and tailroom the hardware may need, but not in all cases
+ * can this be guaranteed, especially tailroom. Some cases also use
+ * LL_MAX_HEADER instead to allocate the skb.
+ */
+ unsigned short needed_headroom;
+ unsigned short needed_tailroom;
+
struct net_device *master; /* Pointer to master device of a group,
* which this device is member of.
*/